Geology of Placer Deposits (1964)

G EO E O LO LO GY GY

O F P LA LA CE C E R DE D E PO P O SI SIT S

SPECIAL PUBLICATION

34

Calif Ca liforn ornia ia

Divis Di vision ion of Mine Miness and Ge Geolo ology gy Ferry Fer ry Bu Build ilding ing,, San Fra Franci ncisco sco

G EO E O LO L O GY GY

O F P L A CE C E R DE D E P O SI SIT S B y O lA lA F

P . J EN EN KI KI NS NS

Chief, Ch ief, Div Divisio ision n of Mines and Geo Geolog logy, y, Ret Retired ired

acc ac ces essi sib ble thre th ree e The

exploration

near arly ly

alll al

phy ph ysi sio ogr grap aphy hy has been been

of

and an d

give gi ven n

the th e ec eco ono nom mic gra rap phy

of

phases

stre st ream am

is a gre great

par artt

of a geo geolo logi gic c in

in th the e

use

of

with

Placers form fo rmed ed::

are

eollia eo ian n,

and

farr th fa the

mos ostt

stud st udy y

in

and an d

this

the th e

the

redu re duce ced d

deve de velo lopm pmen entt

and an d

ha st sten ened ed

way

strrea st eam m for

of syst system emat atic ic

plac acer erss

Rece cen nt

and

buri bu ried ed,,

but ea easi sily ly

large

exem ex emp pli lifi fied ed the th e

the th e

pla lace cerr

are

is by by

stud st udy y

are ar e

scientific

wor orki king ng

lar arg ger the th e of

foot still

of

bed.

Kla lam mat ath h

deposi sitts: ald al der

buri bu ried ed

ben ench ch

chan ch ann nel elss

gra rave vels ls

that th at

pla lac cers

lie

pockets

beneath

faults

have sti tilll

Moun unta tain in~. ~. pla lace cers rs,,

Placer 

and

may

in

larg la rges estt

af al alll th thes ese e

by

Recent

places

gra rav vel

of 

wit ith h

plac pl acer erss

lava la vas, s,

exist

lies

chan ch anne nels ls

in

the

of the the Sierr Sierra a

pos ossi sibl ble e

remaining

buried

part rt,, grav gr avel elss stat st ate. e.

that th at st stil illl

in more more obscu cure re

posi siti tio ons

whi hich ch fo form rmer erly ly

prod pr oduc uced ed

The Th e de dep ple lete ted d

grav gr avel els, s,

lie

lon lo ne

or

the

as

ben enea eatth

Feather

those

and

found

in

'fa Is Ise e

bedrock'

occurring

in

t he he

form fo rmat atio ion n,

area ar eass

'shore'

de-

and an d the Chic ico o

form fo rmati ation on.. chan ch ann nels

the the

known

and an d

asso as soci ciat ate ed

gold-bear ariing

benches

dist strric ictts

of

the th

gold go ld

and

the th e

pla lace cers rs,,

Kla lam mat ath h

or des eser ertt

is deri derive ved d

dire di rect ctly ly

ass sso ocia iatted between

the

ben ench ches es Sierra

fan fa n dep depos osit its, s,

wner ere e

Mountai ain ns. allu al luvi vial al

from fr om the or orig igin inal al

min iner eral aliz ized ed

sour so urce. ce.

8. Dese serrt

pla lace cerrs,

where

from fr om mor more e an anci cien entt dese de sert rt

the th e

gold

gold go ld-b -bea eari ring ng

stre st ream am

is

rec eco once cen ntrat ated ed

stre st ream ams. s.

plac pl acer ers. s.

stream

The

sco sc ope

of thes these e

pro rob ble lem ms

placers' '  placers

ind in dic icat ate es

of the the ge geol olog ogic ical al

In no no ki kin nd of mini mining ng is geo eolo logy gy

than th an in the the ex expl ploi oita tati tion on

of thes these e

the th e grl rlM Mlt prin pr inci cipl ples es mor ore e ap appl plii-

mor ore e obs bscu cure re

depo de posi sits ts..

of 

lie,, fo lie forr the the mo most st

than th an vast va st

the

ben enea eath th

(Eo (E oce cene ne))

need ne ed of an an under underst stan andi ding ng

rema re main in un unto touc uche hed d

involve

immediate tely ly

Ter erti tia ary chan ch ann nels and lava-covered di strict

Nevada 7. Baj Bajad ada a

plac pl acer er

Cali Ca lifo forn rnia ia

of th the e

in Cal alif if orn ornia

Tertiary

dep epo osit itss

out

state.

cabl ca ble e

gra rav vel

to be be so sou ught

as

such

gravels

in

bedr be droc ock k

Nev evad ada. a.

gold ld-b -be ear arin ing g

lyin ing g such

that th at

Tert rtiiar ary y

6. Burie ied d in the

invo in volv lved ed..

The Th e

The

benches

grav ave e Is Is

(Cret (C retace aceou ous) s)

investigating.

rese re serv rves es

twic tw ice e

Moun Mo untai tains ns..

of th the

S. Buried

and an d

in the

rem re main

rivers,

high

Klam Kl amath ath

pos osit itss

of Cr Cret etac aceo eous us,,

worth

prod pr oduc uced ed

(inte (in terb rbed edde ded d volc vo lcan anic ic layers laye rs)) of th the e dre redg dgin ing g alon al ong g th the e wes este tern rn fo foot ot of tthe he Sier Sierra ra Nev evad ada. a.

type ty pess rere

sti till ll

deposi sitts

large

3. An Anc ient

the

fan ans, s,

havi ha ving ng

Reserves

loca cate ted d

such

seve se vera rall

periods

be

the

allu al luv vial

inte in terb rbed edd ded Mar arin ine e

be-

alo al ong

reg re gions

affo af ford rdss

burie ied d

plac pl acer ers. s.

which

probably

whic ich h

4. Gold-bearing

bed edro rock ck

of

the th e first first

types typ es of dep depos osits: its:

the th e

and an d by

waters

wort wo rth h of gol gold d ca cam me fr fro om

problems

are

down-d -dro rop ppin ing g

doll do llar arss

geologist.

follow fol lowing ing

Plei eist sto oce cen ne

in is isolate ted d

The des eser ertt

gra rave vels ls

baja ba jada da

the

cau ca used

lie

pla lace cerrs

Some

loca lo cate ted. d.

explorati tio on

several

con co nne nect cted ed

are reas as

age. ag e.

easi ea sily ly

to the the inge ingenu nuit ity y

the th e

These

on tru true

grav gr avel els. s.

offe of ferr a chal challe leng nge e

1. Deep

or

whil ile e

work rked ed,,

dred edg ged

chan ch anne nels ls,,

sour so urce ces, s,

9. Bur Burie ied d The Th e

Tert Te rtia iary ry

stre st ream am of Te Tert rtia iary ry

and an d worke worked, d,

of 

uncovered

nott no

alre al read ady y

of th the

Benches

and an d

positions.

Nevada.

Pleistocene,

state,

thre th ree e

The

crit cr iter eria ia

larg rgel ely y

chan ch anne nels ls,,

Sier errra

stre st rea am

the th e mo more re recen recentt Eocene,

in

where

grav avel elss

remote

chan ch ann nel elss the th e

consi sist st

Tert Te rtia iary ry

more mo

bed edrrock'

lie

rivers

wor orke ked d

in

'lo 'l or with with

'fa 'f als lse e

strrea st eam m

as the the

lie

unto tou uched

weste tern rn gravels

strrea st eam m

by hid hidd den

the

Cali liffornia

acce ac cess ssib ible le,,

surf su rfac ace e

lower

neat ath h

of

Pleis isttac acen ene e

reserves

wit ith h

3. Bu Buri ried ed

Klamath. 2. Isolated

dep epllet eted ed

Quat Qu ater erna nary ry chan ch ann nel elss

as mu much ch as th the e ot othe herr tw two o put to toge geth ther er..

is app apparen arent. t. The

and an d

2. Unco Uncove vere red d

thes th ese e

baj ajad ada, a,

further

clas cl asse ses: s:

Abou Ab outt on one e bi bill llio ion n

to

they

of st stre ream am

fall fa ll in into

a

unde un derg rgro roun und d

glac gl acia iall-st stre ream am,,

need ne

as

mat ater eria iall lly y

of exp expensi ensive ve

to t he he

pha hase sess

A

and an d cost ,

ordinary

vari va rio ous

paper.

s

the

stre st ream am,,

Since

imp im por orta tan nt,

discussed

that

according

elu el uvi vial al,,

bea each ch..

ope 'ra rati tion on

out,

ancien entt

applied can ca n

min ined ed

Plac Pl acer ers s

1. Rec ecen entt

wit ith h pho hoto to--

both

when

prin pr inci cipa pall

  Depl Deplete eted d

of whi hich ch

of ae aeri rial al

of plac acer erss,

be gre reat atly ly

classified

resi re sid dua ual, l,

use us e

of ex expl plor orat atio ion n,

result

deve lo deve lop pmen entt wor ork k ca can n an earl ier com comple pletio tion. n.

neit ne ithe herr

The Th e

stu tud dy

dri II in ing the

involving esp spec eciial allly

in co con nne nect ctio ion n

geophysics,

prog pr ogra ram m

gui ding

prospecting,

problem

sed se dim imen enta tati tio on,

con co nce cern rned ed..

aid

The

a

of geo geology,

con co nsi side dera rati tion on

pro robl blem emss

mode mo dern rn..

is

sci cie ence

suff su ffic icie ien nt

and an d

ass i st st

placers

the th e

but are now nearl rly y

the th e wea ealt lth h

deple lete ted d forr the fo the

whi hich ch we were re on once ce re read adil ily y

A wid wide esp spre rea ad tia ti ary

geolo log gic

gold-bearing

Nev eva ada,

the th e gra rav vel

str tre eam deposi sits ts

stu tud dy

of

the th e anci cie ent

channels of whic which h

of

the

TerSie ierrra

are fo fou und to a

larrge la

extent

mat ater eria ials ls,, log lo gic ical al

buried

beneath

was co con ncl clud uded ed

Sur urve vey y

over ov er

"Ter "T ertia tiary ry

Grav Gr avel els" s"

in

thes th ese e

1911,

were we re dr draw awn n

geol ge olog ogic ic

and fr fro om suc such

Lin ind dgr gren en's 's Sie ierr rra a

Colf Co lfax ax

grea eatt Nev evad ada. a.

confined dea eals ls

foli fo lio, o,

deta tail ile ed

subject

Ever Ev eryt ythi hing ng

sibl si ble e

this

work

and an d fi fine nesst

tech te chn niq ique uess

very ve ry li litt ttle le

esca es cape ped d

feat fe atur ure e

bein be ing g

was

done,

it was was pos os--

the

small

recorded.

the th e

best be st

Lin indg dgre ren n's

each ea ch

and an d sh shre rew wdl dly y

inte in terp rpre rete ted d

consid ider erab able le

advance

by

mind mi nd..

then th en,,

are now avail ilab able le;;

poin ints ts

of

degr de gree ee

The su The sub b j  jec ectt of ph phys ysio io<; <;ra raph phic ic geolog geol ogy y or geomorphology in re rece cent nt yea ears rs mad ade e not otab able le progre prog ress ss in de deve velo lop pin ing g

soun so und, d,

scie sc ient ntif ific ic

ori rig gin

of

Sin Si nce

the

thes th ese e

ancie ien nt

vanta tag ge

of refi refine nem men entt

Furthermore,, Furthermore

othe ot herr

of study study

min inin ing g

itse it self lf

toda to day y ov over er th the e ea earl rlie ierr

has

and an d di diffand an d a

is th ther eref efor ore e

has

many

in

advan-

the th e

Aerial Aer ial

Stud St udy y has

From Fr om the air, air,

which hold ho ldin ing g V.

of th the e

take ta ken n

phot ph otog ogra raph phss

aeri ae rial al

phot ph otog ogra raph pher erss .

by qua quali lifi fied ed

then th en

exam ex amiined

stru st ruct ctin ing g

under

com co mpl plet eten enes esss fore

of

realized

are

trut tr uths hs

impa im part rtan antt

prob pr oble lems ms

loca lo cati tio on

thus

great gre ates estt

of

the

prac pr acti tica call

geologist;

lowlo w-co cost st

num nu mbe bers rs

are ar e

u se sed mos ostt

aid whic ich h they

They Th ey

has

for

thes th ese e

und ndo oub ubte ted dly the

secr se crec ecy y,

spee sp eed d,

af mo mode dern rn

many ma ny

a base

mop opp pin ing g, are ar e

Geop Ge ophy hysic sical al Add dded ed

insig igh ht by trie tr ied d ture ture with

into

sever sev eral al and an d

the

regi re gion onal al ver ery y

types

of

standa stan dard rdiz ized ed..

and co and com mpo posi siti tion on precision by

inte in terp rpre reta tati tio on geologic

of al alll

reas re aso oning,

deta de taii led back backsr sro oun und d is made made mo more re ef effe fect ctiv ive e

the

geo eop physi sica call

eart ea rth h

is the the itse it self lf

char ch arac acte ters rs

thus th us

obta ob tain ined ed

it is im imp port rtan antt of ge geol olog ogy y by aeri aerial al

that

shou sh ould ld

forr fo

plac acer ers, s,

expl ex plor orat atio ion, n,

Ther Th ere e

are ar e

toda to day y

avai av aila labl ble e

whi hich ch may be ext exten ensi siv vel ely y This sort of r es esearch in-

cludes clud es th the e crit critic ical al stud st udy y of tex textu ture re and an d stru struct ctur ure e of strat strata, a, as wel elll as the micr cro osco cop pic exam amiinati tio on of th thei eirr miner eral al groi gr oins ns..

It sh shou ould ld

con co nce cern rnin ing g

the th e

grovels,

in t he he

of go gold

more

long

hea eavy vy

the th e

par arti ticl cles es wer ere e

they th ey

cam ca me

of

These mine mi nerr,

of op opin inio ion n

have

and

at

as to thei theirr

of

working not

sedi se dime ment ntat atio ion n miner,

sim si mple

alll al

Also

len ens, s,

he use sess

crite teri ria a

the th e

of st stream now us used

under erg gone is

by

chan ch anne ne Is or

dire rect ctiion

there

who,

han and d

f ro rom m ea earr li lier er

him the the

present

corr co rrel elat atio ion n syst sy stem em..

stre st ream am the th e

flow,

conc co ncen entr trat atio ion n

in the the

fro fr om a vei vein n.

to tel tell

howev ever er,,

ic test,

in

the th e

and an d

under

and a few few other

of 

stream

experienced

robb ro bbed ed

dire rect ctly ly

gro rov vel elss

info in form rmat atio ion n

accum accu mula lati tion on

or of of th the e so som me

by the

they th ey

of

as re rega gard rdss

peri pe riod od

gold

whet ethe herr

direction

crite teri ria a

used

pra ract ctic ical al

in th the e

min iner eral als, s,

obvious

been

exa ex amin inin ing g

scientif 

and

to expe expect ct

othe ot herr

of

invo in volv lved ed

of the the so som me

The

infe in fers rs

a wea wealt lth h

nature

of wha whatt and an d

of chan channe nels ls have

yiel yi eld d

proces proc esse sess

by

a th thoro rou ugh

a wide

diff di ffe erence

inte in terp rpre reta tatt ion.

The adv advanc ance es terpretation w id ide

in tech techniq niqu ue

should ld,, practical

aids

much mu ch mo morre defin init ite e gaine gain ed

and sou ound nd ge geol olog ogic ic

the th erefore fore,, in

be made

chann nne el

and conclu lussive

now t ha han were po poss ssibl ible e

of

grea gr eate terr affo af ford rded ed

elu luc cid ida atin ting g

In-In

to se serv rve e

exploration xploration,, res esult ultss

years

grap aphi hica call lly y

ancient

str trea eam m

of

old

the

met eth hod

vall va lley ey

as and

sho houl uld d

be

ago go..

drain ina age

the th e pos ositi itio on surf ace. ace.

sup upe erimp rimpose osed d

rock rock

strucstru c-

show sh ow th the e pr prese esen n t surf ace ace

req re qui uire ress

a bet bette terr

soun so und d

and more and an d th thii s

butiion but mine min e

of the workings workin gs,,

overr ove

a

base

surfac urface e

of  an

a cont ntou ourr cont co nto our urss

map whi hic ch

may be

shou sho uld

and area eall as

well

map also

di stri ri-as

any

etc.

cont nto our urss

contour ontours, s,

in de dettail

and co cour urse se

f orm rma ati tio ons,

dri rill ll holes es,,

be made of th the e thi thic ckn kne ess,

The

topog to pogrraph phy y

geolog ogiic

With th the e oldold-ssurf ace pre pr esent

of tr trac acin ing g

is by prepa eparin ring g

wellwel

be drow drown n,

phot ph otog ogra raph phy. y.

in th the e de des! s!'r 'rtt

des eser ertt

and

are not are not on only ly re reve veal aled ed butt meas bu measu ure red d skillful engineers. Since the proper resu re sult ltss

the

the th e st stud udy y of sed sed imen imenta tatt io ion n has has no now w re ac ache hed d

now

inst in stru rum ments,

Pecu Pe culi liar ar

at wo work of

expl ex plor orat atiion.

view vi ew fr fro om the ai airr of

physi ph ysiog og--

pro robl blem em..

pro roce cess sses es

unders rsta tan nding

met eth hod odss of tech techni niq que to s tr tream deposition.

and show owin ing g

inter eriior

Tertia Ter tiary ry

more whic ich h

hands

Surv Su rvey eyin ing g

to thi thiss

chan ch ann nel

of deve develo lop pmen ent. t.

The Th e mos ostt II.. II

now no w exti extinc nct) t)

over

Sedi Se dime ment ntati ation on

stag st age e

variou vari ouss applied

beeye .

and an d

as

Nev eva ada,

conco

the

yet rea each ched ed

give

to th the e pr prog ogra ram m

in nev ever er

reve re veal aled ed,,

surf su rfac ace e

are ar e

Sier erra ra

ear arth th..

to th the e

omaz om azin ing g

before

Used

une nexc xcel elle led d.

besides

surv su rvey eyin ing g

or

fea eatu ture ress

them th emse selv lves es.. and an d

pict pi ctu ure ress

the th e

unfolded

obse ob serv rvat atio ion ns are ar e

show sh ow

surrfo su foce ce

simply

solv so lve e

pho hoto tog gra raph phss

the th e

Man any y

in gre great at

of fiel field d

whi hich ch

syst sy stem emat atic ical ally ly

The

stereoscope,

mop opss

detaill. detai

Geo eolo logi gic c

aeriial aer

the

topo to pogr grap aph hic

are ar e

of the the

and

Proc Pr oces esse sess

geol ge olog ogic ic

Furt rthe herm rmor ore, e, a ref refin ined ed

history

appl ap plic icab able le

offer a practically virgin fiel fi eld d a pot pottt·nt ntia iall wea ealt lth h no nott yet kno now wn.

Strea St ream m

the th e

regi re gion onal al

the th e

stre st ream amss

led to a bet bette terr

flow.. flow

Photog Pho tograph raphy y

of

the

con co nfi fig gura rattion

are ar e direc directl tly y

Stud St udy y of Deser Desertt

'shiingling' 'sh I.

surrfac su ace e

surfa fac ces

Tert Te rtia iary ry

con co nce cern rniing

is th the key to the the an anci cien entt

raphy

whet eth her

meth me thod ods. s.

pres esen entt

ear arth th

flow fl owed ed

prin pr inci cipl ples es

prin pr inci cipl ples es

know kn owle ledg dge e

however,

fere fer ent

tage ta gess

and an d

k een obser observa vati tion on,,

techn tec hniq ique uess;

order.. order

At the

equi eq uipm pmen entt

been made in exp xplor lorati ation on gre reat ater er

scale

of the the day day were were em empl ploy oyed ed,,

scru sc ruti tini nize zed d

his maste terf rful ul Sin inc ce

on a map of

for it

of th the e quad ad--

whic wh ich h

hass ha

was

is th this is fo foli lio o

the th e geolo log gy

Physiography

IV.. IV

channels ls,,

to the in inc ch - was was

field

as ] .D .D..

in 190 1900,

howe ho weve verr , stream

of

to ac acco comm mmod odat ate e

tim ti me

Rans Ra nsom ome, e,

E. Bro Browne wne..

of im impor orta tanc nce e

used - two two mile less

from

sou so urc rce es

publ pu blis ish hed

of

wit ith h ev eve ery phas ase e

ran ra ngl gle. e.

data

fie fi eld stu tud dy of th this is kin ind d in th the

By no no mea eans ns,,

to the

His

F.L.

earl rly y

and an d Ro Rosss

mann ma nner er,,

obse ob serv rvat atio ion ns,

-H. H.W W. Tu Turn rner, er,

III.. III

Geo Ge o-

ago ag o. Lin indg dgre ren n's

stud st udiies.

from fr om his ow own n ca care refu full

Whitney,, W.H. Storms Whitney Storms,, the th e la lasst

Stat St ates es

summ su mmed ed up up,, in a sp sple lend ndid id

var ario ious us

.S.. Di .S Dille llerr,

of  -volcanic

by th the e Uni nite ted d

hal alff a ce cen ntu tury ry

tho th ose of his his associate sociates, s, and] an d]

a man mantle

sup upe erimp rimpose osed d

an acc accur ura ate ext xte ent nt,,

estim tima ate

and ya yard rda age

on th the e may of th the e

inte int erve ven ning

chann nne el-fill l-fille ed

to be used

in prepari rin ng

should and

be se secur cure ed

area. ar ea.

an old ld--sur urfa fac ce

thro th rou ugh

physio iogr grap aphi hic c

The Th e point pointss

car are eful

cond co ndit itio ions ns,,

the

geoph ophys ysiical

should

also

be

enough stud tudy y represe epresen nt

of

repr prese esent nte ed

should

geophys geoph ysiica call of poin pointts

and dr dril illin ling g

need ne eded ed..

to surfa urface ce

use sed d

unlik ely

geologi ge ologisst, Thi hiss

othe oth er

volcanic

area ar eaJ J

Thus

materi ria als

the

to wh which ich lat late er

demuch

areas

eleva evation tionss

it is in dir irec ectt

con-

or wit with h th the e pip pipe e-clay

and

the oldest

inv in ves esti tig gation

period

should

of th the

limit

the

work , wh whic ich h in tu turn rn de defi fine ness

to be dri rill lled ed

unde und ergro roun und d

loca lo catte

wor ork k in adj djo oinin ining g

of

of the the geo eop phy hyssic ica al

area

sho houl uld d

thuss elimin thu limina atin ting g

whe wh ere

gravels,

geolog geolo gic ical al

as a pr prelimi-

The Th e mos ostt acc accur ura ate

taken on bedro droc ck

con-

thou th ough gh he is limited

vall va lley ey

and mo morre costl tly y

tact ta ct wit ith h th the e ol old der

old-surface old-surfac e

map

be co confin nfine ed,

to be produ produc cti tive. ve.

are tho those se

muc mu ch ti tim me and an d nu numb mber er

be co constru truc cted

tre tr end of the the ancient

unnecessa unn ecessarry

the th e

Carreful Ca

as we well ll as in th t he numb numbe er of 

data.

work  shoul hould d

pro pr ogram gram,,

An approximat pproximate e

nary step by a skil skillful lful

ext xte ent

map.

in th the lo loca cati tion on

of ob obsservation rvation,,

tou to ur map may generally

tail ile ed

this th

work is don done e pri prio or to a cont conte emplat mplate ed

sur urv vey

holles ho

gen ge neral

obse serrva vation tionss

be mad made e so th tha at th the e point pointss

and money ma may y be sa sav ved

only

data and

only on one e peri riod od of  ero rossion.

If the the ge geologi ologic c

drill dr ill

duri du ring ng

Dri rill ll-h -hol ole e

on

map ma p

of  ge geologic ologic

obta ob tain ined ed

surv urve ey.

res esult ultss

conto co ntour ur

stu tud dy

and an d

the surf ace and unde underground essen esse ntial

which are

and

latter la

to be explored

by

metho me thod ds.

Exam Ex ampl ple e

of a geo geolog ogiic

top to pograp aph hy

The Th e so so-c -cal alle led d

'bur 'b urie ied d

part pa rt in the the nor orth ther ern n Tert Te rtia iary ry burs bu rsts ts netw ne two ork serv ser ved ed,,

perrio pe iod, d,

chan ch anne nels ls''

Sie ierr rra a

mil illi lion onss

Nev evad ada, a,

this th is ol old d su surf rfac ace e

in age,

wit ith h

vall va lley eys, s,

and an d wind windin ing g

complete complet ely

all

itss it

hid idd den.

Thu Th us

can ca nyo yons ns

the th e hea eavy vy

mud-fl mu d-flows ows,,

it.. it

But even

cobblecob ble-was washes hes,,

fill fi lled ed an and d re refi fille lled d cany can yon-cuttin ing g

trenched

leav le avin ing g

of flatflat-to topp pped ed

remn re mnan ants ts

Though ancie an cient nt

no

strea str eam ms

was up upli lift fted ed and an d th the e ri riv vers benches bench es

volc lca anic

with wi th gold gold,, became

the th e area

was

further furt her

ridge dgess

mantl tle e

Tert Te rtia iary ry were

left le ft

area

entr tre enched. vari rio ous

surf rfo oce

(das (d ash hed

con co nto tou urs

val allley

is

thus thu

(fin (f ine e,

the lines es))

full

the ore

lines es). ).

rec eco onst stru ruct cted ed,,

earlie ierr

pre ressen entt

dra raw wn

the the

Old ld--

over pres esen entt-

A ma majo jorr

and

prev pr evol olca can nic

top to pograp aph hy. earl ea rly y

gen ener eral al

Ter erti tiar ary y

posit itio ion n

of 

its buri ried ed st stre rea am chann chan nel is indic.ated, lying be bene neat ath h vol ol-caniic mate can teri rial alss of tw two late laterr geo eollogic per erio iod ds, i.e., (1) Mi i.e Miocene

cobble

and

Pliocene

lava

and an desi siti tic c

moter eria ials ls..

gold-b -bea earrin ing g. foll fo llow owed ed The Th e

expl ex plai aine ned d

The

cont co ntac actt

sou so uth

(mu (m ud-f -flo low ws

which

Its Cou Course

the th e

gra rad dient

dire di rect cted ed

pipe-c -cla lay y

flow

followed old lder er

was

lava

as wher where e

chan ch ann nel

fl ow

by th the e we west stwa ward rd

by

hard ha rd di dior oriite is

it t ur urns tilt ti ltin ing g

not

lak ake e

c an anyon cutt cu

contro rollled

betw be twee een n

of th the

and an d a

as

towards

in

bedrrock  bed

steep

is

for it it

soft so fter er

the

(2)) (2

in the

bed edrrock ck,,

and an d

of th the e Si Sier erra ra

bed edss), cut

schi sc hist st..

where

west.

it is

This

is

Neva Ne vada da..

modern deeply ly,,

betwee bet ween. n.

ever

con co ntours

wit ith h

of lavas lavas,,

alo lon ng th the e sid ide es

covered

of the the canyons ons..

the

an impo import rtan antt

role ro le in the the his isto tory ry

the reg region ion

goldgo ld-be bear aring ing

grav gr ave els

and an d Qua uate tern rnar ary y at

wha hatt-

surrfa su face ce

map s ho howing

contr co tras astt

volcani volc anic c

form fo rmed ed.. Fi Fina nally lly,, whole

by

cutt th cu thei eirr

and an d ex expo pose se

the th en,

the

were therefore

of gra rav vel

lifted

riv ri ver erss

of the Kl Klam amath ath Mo Moun untai tains ns,,

in late late

beautiful

and an d ne new w st stre ream amss

the th e va valle lleys ys

Eocene Eoc ene

hil ills ls,,

did di d th the e la late terr man antl tle e

the th e outou t-

and an d prepre-

probab pro bably ly

lade la den n

Not until

forc fo rces es

ever was beneath

entr en trap appe ped d

forrest fo st-c -co overe red d stre st ream amss

dur urin ing g

volc vo lcan anic ic

the th e th then en ex exis istin ting g

of th the ea eart rth h,

moun unta tain in-m -mak akin ing g thro th roug ugh h

ago, ag o,

cove co vere red d

cou co urs rses es..

forr th fo the e mo most st

wher ere, e,

of yea ears rs

with wi th th thei eirr mu mudd-fl flow ows, s, of strea stream m

occu oc curr

in

tim ti mes es,,

As a result sult,, ele lev vati tio ons

The whole gio ion n,

past

intere int eresti sting ng

sub su bje jec ct

whic ich h

alsso pl al play ayed ed

of the the upl plif iftt,

trapping

date back to the the Eocene.

of the the su surf rfa ace

and present, prob pr oblem lemss

Faul Fa ulti ting ng

rep re prese esen nts

~lOtyet enti ntirel rely y

fea fe atu turres a se series solve so lved. d.

of the the re re-of ve very ry

In the Mo Mojav jave e

Deser De sert, t, Ter Tertia tiary ry

may have have on once ce fl flow owed ed so sout uth h now no w th the e

Sier Si erra ra

epoc ep och h th thei eirr by

faulting,

desert

and

wash,

reco re cogn gniz ized ed The

that

problem

butt du bu duri ring ng

the th e Pl Plei eist stoc ocen ene e

so br brok oken en an and d di disr srup upte ted d

extensively

now· there

covered

remains

by lat later

little

of the

an immense

'dry

placer'

is

one

poss po ssib ible le,,

potential

how ho wev ever er,,

gold

wealth

may

to find find an and d de deve velo lop p

unde un derg rgro roun und d

wate wa terr su supp pply ly in man many y pl plac aces es

oper op erat atio ions ns..

The fi find ndin ing g

also al so be gre great atly ly knowl kno wledg edge e

of suc such h

assi as sist sted ed

Peni nins nsu ula larr

some so me place placers rs

of the

vari va ried ed..

wat ater er

of

spen sp entt

in vai ain n.

loss lo sses es

foun und d

be dis-

cons co nsid ider er

itss re it rela lati tion on

most

of its its

slig sl ight hted ed,,

forr it fo it re repr pres esen ents ts

weal alth th

for Cal aliifor orn nia ia..

min inin ing g

indu in dust stry ry

may

instructive

unde un ders rsta tand ndin ing g

pla lace cer, r,

poss po ssib ibil ilit itie iess

a vast vast fu futu ture re so sour urce ce

of gol gold d

they th ey su sugg gges estt

stre st ream am co cour urse ses, s,

chan ch anne nell not be

of the the

chan ch ann nel el--

mor ore e in inte tere rest stin ing g

of th the e detai detaile led d

geol ge olog ogic ic

forr cer fo certa tain in

and an d th the e re real aliz izat atio ion n

by an

feat fe atur ures es,,

of th thes ese e

the th e

buri bu ried ed

of the the vast vast ex exte tent nt

of the the re regi gion on ye yett to be ex expl plor ored ed.. Sin ince ce dese de sert rt

an es esttim ima ate

plac pl acer erss

mining

depe de pend ndss

of them,

the heir ir pla lac ce

of the the pot oten enti tial al upon up on furt furthe herr

it is

in th this is

not yet

wea eallth

of

expl ex plor orat atio ion n

possible

or

vice vi ce

to

geo eolo log gic are ar e

sho sh ortl tly y

aft fter er

disc di sco over ery y

stream

courses.

chan ch anne nels ls

the

In

of gold

places,

of

thei th eirr

Star St arti ting ng

uncovered

volc vo lcan anic ic from fr om th thes ese e

channel

to

cove co vere red d

by the the la lava va ca capp ppin ing, g,

ano noth ther er

kind ki nd of 'f 'fllat at.' .'

in the

remnants

the

flat fl ats, s, the

segm se gme ent ntss

hist hi sto ory

irre ir regu gula larr The

f in inal ly ly

hidden

thes th esee

meth me thod odss

explo exp lora rati tion on

'ex expe pens nsiv ive e

drai dr aina nage ge

ele lev vat atio ion n

To pla place ce

to se serrv( v(;;

thei th eirr

in or

poss po ssib ibil ilit itie iess

as wel well surf su rfac ace, e,

as to th the

comp co mple lex x

and an d

is th the e probl problem em to be be faced faced.. i s ge ge ol ol og ogy,

prospec ti ting

aided

by a er eri al al

sur~ su r~ey eyin ing g,

t hr hrough

or tunn tunnel el..

sho sh oul uld d

res estt

whi hich ch en ente terr in into to

by ge geop ophy hysi sica call

incl in clin ine, e,

and an d

surface,

affo af ford rd al allu luri ring ng

foll fo llo owe wed d

shaf sh aft; t; ,

stil st illl

from the the

and an d ge geop oph hys ysiici cist st

direct ed di ed

benc be nche hess

whic ich h

pass pa ssag ages es

to th the soluti on on

drill dr ill,,

pres esen entt

an

To

me an ans

be

be co coor ord din inat ated ed

and  an d  of

the

effective,

all

into in to one one unif unifie ied  d 

prog pr ogra ram. m.

where

it

was

alw al way ayss

type ty pes, s,

form fo rmed ed..

The Th e

Res esid idua uall

B.

Elu luv vial tional

wass th wa the e mos ostt se seri riou ouss

prob pr oble lem m,

forr the fo the ol oldd-ti tim mer erss

nott ha no have ve th the e po powe werf rful ul

pump pu mpss wh whic ich h we use use to toda day. y.

clas cl assi siff

condit con dition ionss

into

how ho w th they ey

wer ere e

fir irst st

icat ic atio ion n

is

base ba sed d

upon up on

of dep deposi ositio tion: n:

Cla lass ssif if

plac pl acer erss or

them

ica ic ati tia an

or 'se 'sea am

'hills 'hil lsid ide e'

of

Plac Pla cers

dig iggi ging ngss.'

placers,

from

C.

pla pl ace cers rs,,

a na nam me

appl ap plie ied d

type ty pe of 'd 'des eser ert' t'

or 'd 'dry ry''

plac pl acer er..

Baja Ba jada da

sorte so rted, d,

purp pu rpos ose e

foll fo llow owin ing g

callls ca

dividing

'creep'

D. Str Stream eam

best be st

indi in dica cate te

of pla place cerrs

residual

rep re pre ressenti tin ng deposits

tra tr ansito

s tr tream

gravels.

of lo long ng and and tunn tu nnel elss

whic ich h

Fundamenta tall

A.

stud st udy y

classification

the th e fundam fundament ental al

en-en

thes th ese e

geo eolo log gic ica al

orderly

gene ge neti ticc

the th e to top p of whi which ch fo form rmed ed

whi hich ch le led d to the the co cons nstr truc ucti tion on

at the pro rop per

by

of eng engin inee eerrs

Frag Fr agm men enta tary ry

dep epos osit itss

in the the ex extr trem eme, e,

  pho photo togr gra aph phy, y,

what

of the the burie ied d

the be best st

A th thre reee-di dime mens nsio iona nall

k ey

refl flec ects ts

strruct st ctur ure e

tha hatt

by the them m.

completelr

to th the geo eolo log gis istt

hist hi sto ory

and an d

of ric rich h gr gra ave vell

prospector.. prospector

the th e miner minerss fo foll llow owed ed

Wate terr was near arly ly

tunn tu nnel els. s.

foll fo llow owed ed

by Ple Pleis isto toce cene ne

coun co unte tere red, d,

a

whic wh ich h mi migh ghtt be expe expect cted ed

rec ecor ord ded

the th e lo lowe werr ma main in ch chan anne nels ls

of Ter Tertiary

point

as to prov ovid ide e

and an d

high hi gh up on on 'flat 'flats, s,''

cove co veri ring ng

of th that at

to evaluate

chan ch anne nels ls

were we re fo foun und d ly lyin ing g ex expo pose sed d

stri st ripp pped ed'' eros er osio ion. n.

the th e

Tert Te rtia iary ry

the

and to

cond co ndit itio ion n

rela re late ted d

hist hi stor ory y

so com omp ple lex x

A sy syst ste emat atiic

of the the

carefully

may ma y be expect expected ed.

. ha have ve be been en ba baff ffle led d

stu st udy.

disc di scov over ery y

follow

to the the geol geolog ogic ic

the

vers ve rsa a;

chan ch ann nel elss

for

The Th e

the

for orm m of of min inin ing g

of mi mini ning ng in a giv iven en dis isttric ictt

geolog geo logic ic con condit dition ionss The

sho sh oul uld d

is mad ade e st stil illl

gained,

to be fou found nd in anot anothe herr ar area ea if the ge geol olog ogy y we were re kn know own, n,

Bal alle lena na

rev eviv ival al

wer ere e

guid gu ide e to the the pr prob obab able le

of the the buri buried ed

The

led le d

of dol dolla larrs

forr dred fo dredgi ging ng supp su ppli lies es

exp xpllor orat atio ion n

and

phys ph ysio iogr grap aphy hy

as to st stam amp p thi hiss

even ev en fr from om th the e un unde derg rgro roun und d

and an d th the e im imp porta tan nce

many

the millions

The two ar are so clo close sely ly

positions

sign si gnif ific ican ance ce

and an d

a suffi suffici cien entt

as 18 1893 93..

The Th e ec econ onom omic ic

were

mill llio ions ns

of

cou ourrse sess

in the the ex extr trem eme. e.

hist sto ory

San Die iego go Cou oun nty ty,, the th e

In spite

reco re corrde ded d area ar ea..

channels

and an d

wer ere e so grea greatt is

the

of Ter Terti tiar ary y

ast strray ay,,

abou ab outt

have ha ve be been en mi mine ned. d. In the the Po Powa way y (E (Eoc ocen ene) e) is

ancient

It

It is quit quite e

con once cerrni ning ng

Mis isco conc ncep epti tion onss

many per erso sons ns

survey sur veying ing..

Rang nges es

cong co nglo lom mera rate te

know kn own n as ea earl rly y

positions

dev evel elop oped ed

con-

thro th roug ugh h th the e use of ge geol olog ogic ical al

and geo geophy physic sical al

In th the e

of

and an d when when more more is learn learned ed

whi hich ch ha hass no nott ye yett be been en gl glim imps psed ed..

mar ariine

to be

The ide deas as

as hazar hazardo dous us

impo im port rtan ance ce,,

cove co vere red d

from fr om the the re regi gion on whi hich ch is

beca be cam me so

stream str eamss

or tr trac aced ed..

side si dera rabl ble e it,

Nev evad ada; a;

depo de posi sits ts

goldgol d-bea bearin ring g

E. F,

did di d

plac pl acer ers s simpl ple e

depo de posi sits) ts),,

from fr om mora morain ines es,,

forr th fo the e mo most st pa part rt va valu luel eles ess. s.

placers,

Mar arin ine e

or

of lig light hter er

or 'b 'bea each ch''

and  re-

sorted

plac pl acer ers, s,

Eoli lia an

pecu pe culi liar ar

and an d co coal ales esci cing ng..

Glaci Gla cial al-s -str trea eam m

the th e re remo mova vall G.

(allu (a lluvi vial al

to a ce cert rtai ain n

grav gr avel el

local lo

concentra rattio ion ns

mate ma teri rial alss

plac pl acer ers. s.

depo de posi sits ts

tran tr ansi siti tion onal al caused

by th the e win ind. d.

by

Of thes these e

seve se ven n

type ty pes, s,

the th e or ordi dina nary ry

by fa farr th the e mo most st im impr prot otan ant. t.

IS

more mo re or le less ss

inte in terr rrel elat ated ed

are ar e al alll su subj bjec ectt

and an d

to def defor orm mat atio ion n

wel elll

known

name,

vari va riou ouss

or bur buria ial, l,

call lle ed

'dry 'd ry''

Insti tu tute

 Engineers

Tec ech hnic ica al

whic ich h of

he

Publi lic cat atio ion n

hass be ha been en de desc scri ribe bed d

or so soana an aly lyz zed

1935).

The Th e

of win wind d in Wes Westt-

by T. T.A. A. Ri Rick ckar ard d

Inst In stit itu ute

of

Tran Tr ansa sact ctio ions ns,,

Engi En gine neer erss

the th e

M et etall ur urgical

488,

ern er n Aust Austra rali lia a

(Ame meri rica can n C. Hoover (A

desert,

and

of go gold ld by the the ag agen ency cy

  Meta Metallu llurg rgica icall

pro rop pose sed d

car are efu full lly y

Mi ni ni ng ng

conc co ncen entr trat atio ion n Her erbe bert rt

depo de posi si ts are

Web ebb ber

for pec peculiar

pla lac cer ers, s,

(Ameri ca can

they th ey

perio pe riod. d.

B.N B. N.

placer"

plac pl acer er

howe ho weve ver, r,

and an d th they ey may

type ty pess of pla place cerr

in Ala lask ska a.

"Baja jad da

are, ar e,

inte in terg rgra rada dati tion onal al;;

be fo form rmed ed durin during g an any y ge geol olog ogic ical al Mos ostt of th thes ese e

stre st ream am

Alll ty Al type pess

and an d

Minin Min ing g

voll. vo

and  an d 

28,, 189 28 1898, 8,

pp.. 49 pp 490 0 - 537; 537; 75 758 8 -765). -765). General Gen eral

In valu valuat atin ing g tions

should

Statem Sta tement ent

a plac placer er,, be

the

one on e of the the fi firs rstt

determination

form fo rmed ed..

It is re reco comm mmen ende ded, d,

ration

engineer

grav gr avel el de depo posi sitt

should

of th the e

and an d

pro roce cess sse es

of th the e

for th the e formati tio on cam ca me

a cle lea ar

This Th is have

call ca llss

and an d

unde ders rsta tan ndi din ng

the th e re reg gio ion n resp re spo onsi sib ble

as well

as

fro fr om it itss

of a dep deposi sitt

each

forr an fo an unun-

of

been

or modi difi fied ed

more in inte tell llig igen entt

it was

genetic ica ally

the deposit,

sam sa mpli lin ng

how

that th at th the e ex expl ploo-

geo eolo log gy

whic ich h

of

form fo rm.. The actu tua al when

cla lasssify

his isto tori ric cal

to be pre rese serv rve ed

in a much

ther th eref efor ore, e,

to be pr pros ospe pect cted ed..

der erst sta andin ing g

of

cons co nsid ider eraa-

the th e

stag st ages es the th e

orig or igin inal al

is car arri ried ed

sati sa tisf sfa acto tory ry

of

Diag Di agra ramm mmat atic ic

how it

TYPE TY PES S

OF TH THE E OF

setse t-u up

In ord orde er ori rig gin ina al

tha th at

sou so urc rce e

in

by lo long ng-c -con ontin tinue ued d

four fo urth th,,

Sket Sk etch ch

map

bedro roc ck,

the th e

and

the th e

the th e

The Th e su surf rfac ace e

mate teri ria al

weat we athe heri ring ng..

chemical

The Th e

geol ge olog ogic ic

brea br eaki king ng-d -dow own n

decay

of

of 

of a gold gold-b -bea eari ring ng

ore or e bo body dy will

duri du ring ng th this is pr proc oces esss

of ro rock ck di disi sint ntee-

grat gr atio ion, n,

som so me of th the e so soft fter er

and an d mo more re solub soluble le

part pa rtss the

of the the ro rock ck ar are e ca carr rrie ied d remain iniing

sidu dual al re si

portio ion n

plac pl acer  er 

is

Aft fter er th the e re resi sidu dual al tive ti vely ly

inex in expe pens nsiv ive e

rock ro ck is en enco coun unte tere red, d, chan ch ange ged d the lod lode. e.

of

applie ied d port po rtio ion n

away aw ay by ero erosi sion on,, higher

tenor.

to this this

typ ty pe

The of

the th e

hard ha rder er

name

deposit.

min iner eral aliz ized ed

and an d th the e min inin ing g met etho hods ds

to ac acco comm mmod odat ate e

leav le avin ing g

is min ined ed aw away ay by com compa para ra--

met etho hods ds,,

anot an othe herr

down

the th e

directly

gravel

dev evel elop opm men entt from

hill as

dep epo osit,

or

of rich rich

the

(Aft (A fter er

vein.

the

mat ater eria iall

plac pl acer erss

disintegration Lind Li ndgr gren en,,

of  

"Min "M iner eral al

)

so-c so -cal alle led d

gold go ld-b -bea earin ring g zone zo ness

'sea 's eam m

quar qu artz tz

digg di ggin ings gs''

strin st ringe gers rs,,

of disi disint nteg egra rate ted d

are ar e

occu oc curr rrin ing g

in we weat athe here red, d, alon al ong g

frac fr actu ture re

schi sc hist sts. s.

the th e minerals ls..

beco be come me en enri rich ched ed beca be caus use e

show sh owin ing g

of  eluvial

form fo rmat atio ion n

mat ate eria iall

auri au riffero rou us

Fir irst st,,

at th the e outc outcro rop p

done

Disi Di sint nteg egra ratio tion n

and an d po powe werf rful ul

the th e mec mecha hani nica call

port po rtio ion n

enca casi sin ng

is most eff ffe ect ctiv ive ely

by per persi sist sten entt

whic wh ich h ef effe fect ct

rock

This

thir th ird, d,

transi tran siti tion onal al

of wat ater er-w -wor ork ked

an

gold - beari rin ng

  Dep Depos osit its. s." "

fro fr om its its

pla lace cer; r;

of resi resid dual

forming plac pl acer. er.

the th e

depo de posi sits ts::

dis isin inte teg gra rati tion on

dep de pos osit itio ion n

strea st ream m

a

rele re leas ase ed

seco se con nd,

slo sl ope pe;;

broken-down

Plac Pl acers ers

surf su rfac ace e

is accom accompl plis ishe hed d agen ag ents ts,,

PRIN PR INCI CIPA PAL L

gold may beco becom me

must be bro rok ken down.

vei ein n;

by 'creep' 

alluvium,

PLAC PL ACER ERS S

Resi Re sidu dual al

quar artz tz

place cerr

hass be ha been en ac acqu quire ired. d. CHAR CH ARAC ACTE TERI RIST STIC ICS S

show sh owin ing g of pla place cerr

to form a residual

on

man ann ner

geolo logi gic c

cras cr asss-se sect ctio ion n

in th the e devel develo opm pmen entt

must mu st be

type ty pe of de depo posi sit, t,

i.e., i.e .,

Aft fter er

gold is re rele lea ase sed d

enca en case seme ment nt eri rin ng,

the th e

the th e hills hillsid ide e heav he avin ing) g)

thro th roug ugh h whole

agen ag ents ts

(in (i n some some re regi gion onss Lin ind dgre ren n

ori rig gin ina al

of roc rock k de deca cay y

weath the ere red d

and an d ma may y final finally ly

to gu gull lle eys.

fro fr om its its mas asss

and an d wea eath th--

may 'c 'cre reep ep''

part pa rtly ly

be was washe hed d

Minera erall in Min

bed edro roc ck 

beca be caus use e

down

of frost frost

down do wn rivu rivule lets ts Depo De posi sits ts

(p.. (p

in-in 213) 21 3),,

stated: Whe hen n the outcr outcrop opss a gra grad dual over ov er ate at ely

the th e

of goldgold-be bear arin ing g

conc co ncen entr trat atio ion n pri rim mar ary y

below.

The

dep de pos osit itss vein

of th the

gol old d

or on on the the when

loca catted

vein ve inss foll fo llo ows, gen entl tle e

are ar e de deco com mpo pose sed d eith ei ther er slo sl ope pess

on a hil hillsi sid de

dire di rect ctly ly imm im med ediibends

over ov er an and d di disi sin nte tegr grat atio ion n the

latter

roc ro cks:

as

the th e

kaol ka olin in,,

lesss le

and an d

wit ith h

brea br eaks ks

a r ul ule

ressis re ista tan nt

solu so lubl ble e

salt ltss.

yiel yi eld d Some

take ta ke

plac pl ace e

The

fin fi nal

washed

ressult re

is

consis ists ts

of gra grain inss but

prima pri mary ry

vein ve in..

On its its

of

The

con co nta tain in

and

gre rea ate terr

irre ir reg gula larr

tha th an

in su suff ffic icie ien nt

Such Su ch dep depos osit itss

tha th at

the th e

ha's

a

gold go ld is so som met etim imes es

luv via iall as elu

between

gold

residual

min inin ing. g. They

pla lac cers.

and

stream,

or

deposits.

alluv allu vial,

Ther Th ere e

have ha ve bee een n a numb number of resi residu dual al

gold deposit itss Klam Kl amat ath h

min ine ed

Moun Mo unta tain ins; s;

of Geo Georg rgia ia Siskiyo Sisk iyou u

in both both th the e Sie ierr rra a forr examp fo example le

Sli lid des es,,

and an d el eluv uvia iall

Eld El dor orad ado o

Nevada

the th e 's 'sea eam m

Coun Co unty ty,,

and an d Sco cott tt

Bar, Ba r,

County Cou nty..

By far the most important type of placer is the ordina ord inary ry all allu uvia iall gra rav vel or stre strea am pla lac cer. So fa farr, it has be been en th the e so sou urc rce e but

now its

valu va lues es

of mos mostt of th the e pla lace cerr

supply

rem re mai aini ning ng

is

and an d

channels

tim ti mes es,,

or

pla lac cer erss

are

consis istt

acti ac tio on

incl in clud ude e

whet wh ethe herr left

chan ch anne nels ls

thos th ose e they th ey

merely

of san sands

of run runni ning ng

save

for

whic wh ich h li lie e

a cover cover of lav lava a or roc rock k de debr bris is..

by str strea eams ms

anci an cien entt

gold go ld min ined ed;;

depleti tio on,

in tho those an anci cien entt

deep de eply ly bu buri ried ed be bene neat ath h Depo De posi sits ts

nearin ing g

of bo both th pr pres esen entt

form fo rm wellwell-de defi fine ned d

as

benches.

and gra rav vels

wat ater er..

Str tre eam

sort rte ed

delt lta a

pla lac cer,

som so me

min inor or

poun po und d

by th the

If they they ha have ve un und der ergo gone ne

two tw o

and

simp si mple le

plac pl acer ers, s,

in rega regard rd effe ef fect ctss

to sur surro roun undi ding ng

It

is

a

attr at trib ibut ute e

Bulletin All

bench

pla lac cers the th e

739): sim imil ila ar

cours rse e

later

to th those

of

erosion,

sid ide es the th e

of

the th e

str tre eam

the th e

may

be

vall lle ey,

cons co nsti titu tute te

hand,

if

the th e

firs fi rstt

str tre eam left

as

if the the

or

may

be dee deeply

deposit

may

be

practi tic call lly y

condit co itio ion n

seld ldo om

a

pla lac cers

may

valley,

for at

the

deposition point

in

itss it

ben ench ch

and

above

rea re ali liz zed, conti tin nuous of

rew re work rke ed

by

a g ol old where

on th the

is lo low were red d

grav gr avel els. s.

frequent

melt ltin ing g

ice ic e,

sort rtin ing g

debri riss

cert ce rtai ain n

espe es peci cial ally ly

earl ea rlie ierr

1f th the e

forr fo

a very

ancie ien nt

and

deposit placer the

loc lo cal

is

lon lo ng

rec re cent

Since debris

way

as

the th e su subj bjec ectt

of 

be stu studi died ed

clim cl imat ates es,,

The Th e

the th e re rela lati tion on

and an d th the e ef effe fect ct

of 

be co cons nsid ider ered ed.. the placer

mIner

grav gr ave els

to suc such h a bel belie ief, f, the th e strea streams ms be

pla lace cers rs

in

the th e

enough

in

In Ca Cali lifo forn rnia ia,,

hig igh h

Terti tia ary

Sie ierr rra a

tim ti mes

The Th e Pleis Pleisto toce cene ne

duri du ring ng

they

stre st ream amss

robb ro bbin ing g

from fr om

to be fo form rme ed under

cond co ndit itio ions ns..

thro th roug ugho hout ut

glac gl acie iers rs

issu is suin ing g

eff ffec ecti tiv ve

to

to th the

were

cutt throu cu through gh

them th em of muc uch h of th thei eirr

is the soil

larg la rge e

flo fl o~t

has

(28 (2 8th Report

habit

of a

glacier

sort

it at at

of the the

to

but not

t"

agency

of co concentr tra ati tio on

an the

outcrops

masses

of

of ba barr rre en

mor orai aine ness,

have

sai aid d

Sta tate te

p. 309-1 309-10) 0)::

it

and

been

whe here re

fou fo und,

small

are

ice

loose

forr me fo meta tals ls.. is

Att tte empts

of ric rich h

forr tha fo that

off

is w ho holly

veins

eart rth h.

bits bi ts

scrape

all,

thus

mixed

to min mine e

but wide widely ly rea re ason

in-

Gold gold

scat sc atte tere red d

forredoomed fo

to

failure.. failure tain ta inss entire.. entire late la terr

mass,

till ti ll..

slid sl ides es

;s

it

much

Unde Un derr

over ov er th the e

a va vall lle ey

grav gr avel el,,

mix it wit with

whic ich h apt

oth the er

alr lre eady

to gouge

debri riss

and an d buri burie es

the

and dep deposit

some so me circu circum mst stan ance ces, s,

grav gr avel el

con-

out

it

howe ho weve ver, r,

it wit with h

till ti ll

it

wit itho hout ut

it.. it

the

other

hand,

cons co nsum umin ing g

part rtic icle less

thei th eirr

of roc rock

and an d heavi heavine ness ss.. allo al low win ing g are

gold

Nearl rly y

gold go ld al alon ong g

streams

and

min iner eral alss

min ine era rall

to sink sink

in th the exposed

in

gra rav vel

whic ich h

the th e fo foot othi hill llss

the th e

glaciers

accord rdin ing g plac pl acer er

load lo ad th they ey of

t he he has

gla lac cia iall

glaciated been

Nev evad ada a

or

to win inn now

to the the be bedr dro ock ck..

deposit itss

of the the Si Sie err rra a

of pow po wer

may fo form rm gol gold d

veins the th e

the th e

matt tte er

be fou found all

born

have ha ve

way by chu churn rnin ing g

the th e heav heavy y

may th the ere refo fore re

the

mor orai ain nes

Such Su ch st stre ream amss

in th the e wel elll-kn know own n

str tre eam.

down

rive ri verr

as use useless

mer ere ely

the th e

advances

gold go ld-b -bea eari ring ng

known

to

com co m-

and an d ch char arac acte ter. r.

of

may

chan ch anne nels ls,,

Mine Mi neral ralog ogist ist,,

there

action

same

mus ustt

of go gold ld-b -bea eari ring ng

favo fa vora rabl ble e

Bla lack ckw weld lde er

in a lo long

stream

such su ch

or anc ancie ient nt

gold.

slow sl owly ly

the

a in

Plac Pl acers ers

fallacy

but

whol wh olly ly lackin lacking. g.

On th the e other other or late laterr

in th the e

must mu st al also so

to cau cause

Pleistocene,

On

raised,

of th the

dif iffe fere ren nt

pres pr esen entt

cond co ndit itio ions ns,,

however,

occ ccu urr rred ed

dist di stur urbi bing ng

is

and an d cha chang ngin ing g

mine mi nera rals ls;;

de-de

a sec second

fro fr ont

or estuary,

Man anif ifes estl tly y

his isto tory ry,,

do no nott conc concen entr trat ate e

and

Such Su ch

it •• ••••.

sta tati tio onary

a v al alley

In

channel.

base-level buri rie ed

form fo rm a pe perf rfe ectl tly y

that

base-le lev vel

stre rea am

vall lle eys.

or b en enches

down

rem re main inss

str tre eam

terraces

local

laid la id

were

if not

down

so-c so -cal alle led d

regional

peri rio od,

down,

gra rav ve Is, Is,

loc lo cal

to cu cut

t he he

base-l -le evel

laid la id

of the the pre present

pla lac cer

ori rig gin ina al

occur

tim ti me

conti tin nues

posi po sits ts

pla lac cer

when

habi ha bitt,

geol ge olog ogic ic

If a gla glac cie ierr

pla lac cers rs,,

perh rha aps

thor th orou oug ghl hly y

Cont Co ntra rary ry

the th e

but

or buri burie ed

are are

an ope open

a co cont ntin inuo uous us

the th e

lake

by ei eith ther er

acti ac tion on of gl glac acie iers rs..

the

floo fl oor, r, alo lon ng

them th emse selv lves es

the th e depo deposi siti tion on

gla laci cier erss

that th at

upon

some

same

Glac Gl acial ial-st -stre ream am

in al alac acia iall

Surv Su rvey ey

the th e

of the the ea eart rth h

from

Geol Ge olog ogic ical al

into

stre st ream amss

of ex exis istin ting g

derived

Quoti Qu oting ng fro from m J .B. Mer ertie tie (U (U.S .S..

empty

stre st ream amss

vall va lley ey

may be be form formed ed..

to th thei eirr

move mo veme ment ntss

are ar e

plac pl acer ers. s.

wit ith h

grains.

wid ide e

In ord order er to un unde ders rsta tand nd stre st ream am

depo de posi sits ts

vall lle eys

be fo form rme ed

may be ele elevate ted d

stre st ream am

hig igh h

min iner eral al

the th eir

may be form formed ed

as

of the the he heav avie ierr

may

resp re spec ects ts,,

eff ffe ecti tiv ve

of co conc ncen entr trat atio ion n

som so me

geneti tic call lly y

or mor more e pe peri riod odss of eros erosio ion, n, an and d ha have ve been been re re-s -sor orte ted, d, the th e re resu sult lt wil illl in all pr prob obab abil ilit ity y be a com compar arat ativ ivel ely y deg egre ree e

into in to stream s

contig cont iguo uous us

fro fr om

pla lac cer

and an d such such

upst up stre ream am..

and an d

emerg rge e

plac pl ace ers

str tre eams

and

digg di ggin ings gs''

para pa rall llel el

perh pe rhap apss If t he he

to al allu luvi viat atio ion, n,

prog pr ogre ress ssiv ivel ely y

severa seve rall placers

hill s.

gold in th the e

to war warra rant nt

form fo rmed ed

or coa coale lesscin ing g

easil ily y

This

form fo rm an and of

valu va lue e

are ar e cl clas assi sifi fied ed

transiti tio onal

detr trit itu us,

ther th eref efor ore e

pla lain in,,

solu so lubl ble e

chlori chlo rine ne..

gold ld..

from fr om er eros osio ion n

form fo rmin ing g

doubtl tle ess

free fr ee

cha ch ang nges es Whe here re

aurif aur ifer erou ouss and an d

of gold gold

way dow own n th the e hi hill llsi side de,,

conc co ncen entr trat ated ed

redu re duce ced d

rec re covere red d

rough

sli lig ghtl tly y

is gre great atly ly

ferr fe rru ugin ino ous

easil ily y

the

lim li monit ite e,

of iro iron,

solu so luti tion onss

loose lo

conta tain inin ing g

fin ine eness

are

a

volu vo lum me

than

into in to

red re deposit itio ion n

the th e

and an d the qua uart rtz, z, slowly

weath the er

hydr hy drox oxid ide e

and

whe hene neve verr

more

con once cent ntra rati tio on.

gol old, d,

solu luti tio on

and

The

gold go ld

nati na tive ve

much

min ine era rals ls

salt sa ltss.

acc ac com ompa pany nyin ing g

sulp su lphi hide dess

up the the roc rocks

yielding

to siz size e depo de posi sits ts carr ca rry y

and an d

Plac Pl ace ers riv ive ers

if 

area

up-

dre red dged

forr fo

was

dep de pos osit ited ed

by riv rive ers

deri riv ved

the ra ran nge, the th e

low lo wer

cour co urse sess

them th emse selv lves es

and an d

thei th eirr

in par part

but most

dep epo osi sits ts

cen ce ntr trat ated ed

fro rom m

of the

of

such su ch

buil ild d

are ar e

as those those

may

Sie ierrra

be

wit ith h

thei th eirr

the

crest

picked

glo loci cio ol

chan ch anne nels ls

of 

up in

riv ri ver erss

chok ch oke e

pro rog gre ress ssiv ivel ely y,

and an d

not

so wel elll

gra rad ded

riv ri ver erss

con co nwhic ich h

glac gl acie iers rs..

dep epos osit itss

found

Nev eva ada,

Sin ince ce

mor ore e norm rmal al

A few few gol goldd-be bear arin ing g till

along probably

to be be thic thick ker

of the the

are ar e no nott assoc associa iate ted d

was

riv ri ver ers. s.

up

like li kely ly

glaciers

gold

along

as,

in re-w re-wor orke ked d

the

eastern

forr exam fo examp ple le,,

front

in the

As

deb ebri riss

in vo vo lu lum me of wat water er grade

eith ei ther er

(1)) an allu (1 alluv via iall be

faster

result.. result

.... ..

tha th an

agen ag enci cies es,,

The

volume

bulk

., low low angle

at

a hig igh h The

of

periods

a

of str strea eam m

youn yo unge gest st

Bull. Bu ll.

deser ertt

showing

the

dep epo osition

(Aft (A fter er

(6). (6 ).

Surv Su rvey ey,,

gold--bearing gold from

Ferg Fe rgus uson on,,

stream

results the

Uni nite ted d

valley

of

severa

I

oldest

(1) to the

Sto tote tes s

Geo eolo logi gico coll

to

A ba bajada base ba se

is

a c on onfluent

of a mou mount ntai ain n

baja ba jada da

Baj ajad ada a in th the e

rang ra nge. e.

of pl plac acer er

type ty pe

B.N .N..

depo de posi sitt

is the the Span anis ish h

Sout uth hwes estt

fan

along

the

Web ebbe berr de desc scri ribe bed d

the th e

the th e

con co nsi sist stin ing g angle than

and an d

low lo wer

is used used

tota to tall

pro rod duct ctio ion n

sou so uth thw wes este tern rn nott ov no over er

ten te n mi mill llio ion n

Most

of a mou mounta tain in

of rock rock deb ebri riss the rock slope

and an d st stan and din ing g of the range

that

of go gold Sta tate tess

doll do llar arss

pla lac cer

par artt

are ar e Rec ecen entt

.•.. .•

climate

and

plac pl acer er

occu oc curs rs

arid ar idit ity y

in mor more

humid

cany ca nyon onss

by in infr freq equ uen entt

cell ce llen entt

pebb pe bble le

Pro rob bably this these

of

and an d

or

fine fi nerr

the th e

by the the the th e

of

the

grav gr avel el..

the th e

f rom its slop sl ope e

is

ran ra nge ge..

basi ba sin n

lag la g

fill fi ll an and d

lin li ne

and

gra rav vel elss

of the

lin li ne

range

is

lyin ly ing g

standing

foo fo ot

of th the

gold

there

the th e

ran ra nge. is st stiill

for

the th e

more

of  on

for les esss

remain

than th an

con co nce cen n-

and a cercer-

disinte teg gration

tendency

to

det etri ritu tuss

bulk bu lk

in fr fragmen entts

by furth the er

is a str strong

and

be di dis-

dim imen ensi sio on

channel,

locked

at the the dir irec ecti tio on

may

lon lo nges estt

Bec ecau ause se

as in a rive river

released

in th the e

on bed bedro roc ck

of whi which ch

of th the

is on on bed bedrock

is mov movin ing g

values

area ar ea

not operate

slope,

of go gold

lag la g

range,

a larg large e

thro th rou ugh gho out

gold

erratic ica ally

in th the e

case ca se

dis-

of stre stream am

gravels.

Baja jad da surf su rfac ace e she sh eet

sho sh ould

lod lo dge ged d

of th the e char charac acte teri rist stic icss

in one of thes these e

of run running

posit itss

suc su ch

gold

is

slope

The

is too too

freed

cf  

high

to per permit

amou am ount nt

of grav gravel el

the th e

grav gr avel el..

by win ind d an and d

min ine ed

eoli eo lian an

in Aust Austrral alia ia

gold go ld de de--

are ar e known in

however er,, amou am ount ntss involved

process

It is quite

lik ike ely

par artt

IS re resp spo onsi sib ble

of fi fine ne de detr trit itus us has

been

surrfac su ace e

in the the de dese sert rt..

called

that it will will be found

in the the

for th the e redeflation.

to pla play

concen enttra rati tio on

an Im Im--

of de dese serrt

placers. Spurr

desc scri rib bed

Nevad ada a

dese serrt

"au aurrif ife ero rou us

sev se ven

mile less

from fr om the the Cali Califo forn rnia ia of th thee

Silv Si lver er

san sa nd

sou so uth boun bo unda dary ry

Peak Pe ak

line li ne,,

quad qu adra rang ngle le

Pape Pa perr

dunes"

of Sil Silv ver

in th the e

Peak,

18

in hi hiss

(U.S.. (U.S

Ore

Geologi Geo logi--

55).

...• .. .•

gradient

chan ch ann nel els, s,

on th the

be be

during

of st stre ream am

as th tho ose

call Sur ca Surve vey y Profe Profess ssio iona nall

baj aja ada

mat ater eria iall

no co com mmer erci cial al

The

depo de posi sits ts

to

enrric en ich hment

is tr tru ue of so som me of th the e dry pla lac cer erss

thou th ough gh

mov oval al of la larg rge e

ex-ex

of attr attrit itio ion n

This

Win ind d acti actio on,

con co nst stit itu ute seems

show

state. sta te.

mil iles es

on the the

usu sua all lly y

due du e to rem remov oval al of li ligh ghte terr flo loo ods.

are ar e

of th the e mat ater eria ial, l,

effe ef fect ct

Whe hen n a sm smal alll

is tem temp pora rari rily ly

of 

pla lac cer erss

of Cal alif ifor orni nia, a,

fragme frag ment ntss

rock ro ck

of gra gravel.

channels

region re

encoun enco unte tere red d

work

redu re duct ctio ion n

litt li ttle le

a

.•.. .• ..

whi hich ch

small,

disp di spla lays ys

mos ostt

all

accomplished

sho sh ow

movem eme ent

drainag age e

of th the e

nott no

floo fl ood ds

a tt ttrition

percentage

the

intermont

phen ph enom omen ena a

thro th roug ugh h

large

angu an gula larr

a sma small

lodg lo dgm men entt

to

in wh which in

forr the fo the fu furt rthe herr

of

fragments,

phase

region

and

similar

it is conditioned

by ar arid idit ity y

torr to rren enti tial al

mill mi llss

amount as

Quatern rna ary

deposition

Pract ctiically

cond co ndit itio ione ned d

mov oved ed

are ar e de deci cid ded edly ly

some so me

areas.

Roc ockk-fl floo oore red d

slig igh ht,

pro rob bab ably ly

basicall lly y

arid

and

pres pr esen entt

slopes

deposition

bedrock

porta tan nt

is str stron ongl gly y

the

are is

as

of the the

transportation

extr ex trem eme e

but

smal sm all, l,

in th the e

•...• •.

Erosion,

wat ater er

plac ace er

except

topography

bajada reach

this th is gravels

of a bajad ada a

of a sh she e am am pla place cerr

pla lace cers rs

.... .. ..

bajada

genesi siss

fro fr om baja bajad da

is nec eces essa sari rily ly

of all all

the th e la larg rger er The

Unit ited ed

as the

the th e

loca lo call lly y

slop sl ope e

proper pro per .... The

rock

by .... .. ..

mou oun nta tain in

of baj bajad ada a

in

quanti titty

released

the th e

the

as fo foll llow ows: s:

term te rm fo forr slo slope pe

to ind indic icat ate e

range, th ran the e por orti tio on at a much lower

alluvial

the

the basi sin n

to baj bajad ada a of

is

slope

resu re sult ltss

to th the

to he here rea after

to be pa partly

trib tr ibu ute ted d

clo cl ose

and

per erc centage

the

been

the th e co con nta tact ct

of co cont ntac actt

to th the

does

matrix ix,,

723. 72 3.))

of

of th the

outc tcro rop p

lin li ne

of the the

over

is para parall llel el tain

has

slop sl ope e

alo al ong

and an d si sin nce

cre resst

tra tr ati tio on

excess exc

slo sl ope

fan

bajada

pedi pe dime ment nt

the th e

heav aviiest

the

that

ped pe dim imen entt

to a baj bajada

an alluvial

center

se and

angle .. .....

lin li ne,

trib tr ibut uted ed

in

fro fr om lo lod de

is ref referred

wit ith h

at

of

gold

jour jo urn ney

this

dec ecre rea a

of de debris,

to th the

a gr grav avel el-m -man antl tle e

is dro drop pped

coin co inci cid den entt

not

to the the

on the the baj ajo oda

gol old d

lag la g

but

of t he he

on th the

bedrock;

Nevada),

is sup supplied

exii st ex stin ing g The

supplied

debris

of tr tran anssference

mat atri rix x

is

be removed,

capable

just 

dim imin inu uti tio on

and an d an extr extrem eme e deposit itiion

it can can

consider era able

reg re gio ion n

a rap rapid

fan fa n or (2 (2)) a gra rav vel el-m -man antl tled ed

of

th e

slo sl ope

cause sess

If detritus

If roc rock

dep epo osi site ted d

(Manhattan,

channel

formed.

much

baj ajad ada a

due to seep seepag age e

in th the may

of

the th e

glac gl acia iall

north no rth of Mo Mono no Lake. Lake.

Cross-sect ctiion

reac re ach hes

dep epo osi sitt

Con once cent ntra rati tion onss places action sort so rt

along

the

of shore and an d

of he heav avy y Pacific currents

dis istr trib ibu ute

the th e se sea a cl clif iffs fs

the th e

or wa wash she ed

mine mi nera rals ls Coast and

occu oc curr

as

waves,

mate teri rial alss

a re result which

broken

intto th in the e se sea a

In va vari riou ouss of th the tend

to

down

fro fr om

by str strea eam ms.

The

heav he avy y mi mine nera rals ls chrom chr omite ite,,

cons co nsis istt

ilmeni ilm enite te,,

casi ca sion onal al

forr th fo the e most most pa part rt of ma magn gnet etit ite, e,

mon ona azit ite e,

fine fi ne pa part rtic icle less

placers

are of

(b)) an (b ancie ien nt

beach che es.

possit po ite ed

(a) present

An ele elev vat ate ed

wit ith h

terr te rrac ace e

plac pl acer erss

of ec econ onom omic ic

that th at ha have ve be been en re reco conc ncen entr trat ated ed Exce Ex cell llen entt invo in volv lved ed

desc de scri ript ptio ions ns

In dis discussing

Orego Or egon n

beach be ach

logi lo gica call

Surv Su rvey ey,,

the

that

up o ut ut

after

to be

a sto storm

sou so urc rce e

composing zone

the

at one

the

Soundings

of

sand

to

Gold

and

the th e ro rock ckss

The Th e san sa nds

notion

Coast

is

true

gold

and

are ar e

bei eing ng

Geo eo--

as

fact

the

im-

Materials

the

show

sho sh ore res, s,

In

coas astt

of mar arin ine e

Chic Ch ico o (U (Upp pper er Cr Cret etac aceo eous us)) is

she sh e lI lIss,

by

their

content

the th e

occu oc curr

by th the e ch cha ara rac cte terr

of

They Th ey wer ere e

form fo rmer erly ly

wron wr ongl gly y

as "th the e

channel

gra rav vel elss

of

have

als lso o

clas cl asse sed d

a Mes eso ozoic been

Si''nce Si Sie ierr rra a

the

Neva vad da

expec ecte ted d

gravels

of

wer ere e

rich ri chly ly

grav gr avel el--

Gold Go ld-b -bea earin ring g

from fr om ma mari rin ne

sed se di-

of north northern ern Califo California. rnia.

the

Eocene

rivers

gold ld-b -bea eari rin ng,

that th at so som me of th the e go gold ld re reac ache hed d

sedim sed imen en tary dep epo osi ts of th thii s Eocen ene e as th the e lo lone ne fo form rmat atio ion. n.

sea-

the th ei r stra strata ta..

river."

rep re port rted ed

ments men ts of the Lower Lower Cret Cretaceo aceou us

Cali Ca li--

fossil

we II as as

fille led d

In the the

and an d no nott fl fluv uvia iall

as

They Th ey oc occu curr

of

it is

alon al ong g

At the the Tertiarry Tertia

Sierra

accumulated,, accumulated any

riv ri ver

gra rav vel elss

exact

it lin ine e

pro rop per er..

is

which

extensive thus

between The

typical ty

Bul ull. l.

the th e we west ster ern n

descen end ded delta

difficult the th e gravels

lone in

format atiion t he he

from

deposits

in many

form fo rmat atio ion n and an d

placer

Sta tate tes s

Hes' He s's, s,

328.) 32 8.)

beach

Unit ite ed

(Oregon).

Geolo log gic ica al

cross-section in an

of

advanced Pard Pa rdee, ee,

s e e

a

Survey,

c oa oast,

stage

of

Un ite ited d

showing

development.

Stat St ates es

Geo eolo logic gical al

8, 793 7934.) 4.)

Circul Cir cular  ar 

auri au rife fero rou us, larg la rge e

The

tho th ough

deposi ts ts

divi di vide ded d

gen ener eral ally ly

poo oor, r,

the were

con ta tain in

quar qu artz tz gr grai ains ns;;

olde ol dest st

west we ster ern n

quar artz tz

gra rav vels

they th ey are are close closely ly

rive ri verr-ch chan anne nell

the th e ext extre reme me

spre sp read ad

depo de posi sits ts;;

and

fin fi nely

conn co nnec ecte ted d

with wi th

they th ey occu occurr

foot fo ot of the the Si Sier erra ra Ne Neva vada da..

alon al ong g Ther Th eree-

fore for e the lon lone e sed sedim iment entss •..

indicate

delt lta a

deposits

wes estw twar ard d-f -flo low win ing g of

the

sho sh ore ress

lone

formation

of an Eoce Eocen ne

The

show

that

involv lve ed

and an d

the

they

mouths in th the e

of man many y upp up per

acc ac cumulnted

in the the

Eoce Eo cene ne

par artt

on the the

distr trib ibut utio ion n

form fo rmat atio ions ns

If thes these e

and an d

econ ec onom omic ic

hass no ha nott be been en ad adeq equa uate tely ly

and an d

of both both

have ha ve

mari rin ne

have ha ve an any y pa parti rticu cula larr

it certa certain inly ly

at

foss fo ssil ilss

of go gold ld in the the mari marine ne st stra rata ta

stu st udie ied d.

depo de posi sits ts

Mar arin ine e

sea. se a.

processes

conc co ncen entr trat atio ion n Cret Cr etac aceo eous us

formed

stre st ream ams. s.

P RE RE SE SE RV R V AT A T IO IO N

Pla lac cer erss

are ar e

pre rese serv rve ed

chan ch an~i ~ing ng

thei th eirr po posit sitio ioQs Qs,,

are ar e oft ften en le left ft is iso ola late ted. d.

places

to

stre st ream am

lea le aves

and

the

tervals

alo lon ng

are

dest de stro roy y

them th em,, un unle less ss

formation

bec ecau ause se

area ar eass.

neve ne verr del elta ta

the th e been be en

pla lace cerr

signi sig nific fican ance ce,,

demo de mons nstr trat ated ed..

OF

P LA L A CE CE RS RS

if so someth thin ing g

from fr om bei being ng er erod oded ed aw away ay.. Si Sinc nce e st stre ream amss

rivers

Nevada

and

draw

of th the

Survey Su rvey,,

are kn kno own

says sa ys::

mouth

Surv Su rvey ey,,

the th e Col olli lier er

The Th e

foot fo ot of th the e Si Sier erra ra Ne Neva vada da.. Lin indg dgre ren n

a

(  Aft After er

8.)

zon zo nes

car are efu full lly y the

to be be

the th e se sea. a. sea se a

of

Pardee,

Johnso nson n , (A fter Joh

bla lac ck 

gold co con nte tent nt

of abundant

Geo eolo logi gica call

Diagrammatic shore

illu il lust stra rati tin ng

in Ala Alask ska. a.

from

of no nort rthe hern rn

in ori origi gin n

Afte Aft er

loca lo call lly y

ongI on gIn n

sedi se dime ment ntss

That Th at th they ey ar are e mar arin ine e

shown

C.

over ov er

forr th fo thei eirr

Stat St ates es

Circu Ci rcula lar r

the th e

grav gr avel elss

It

\ :;;::'f"~ / / " " 7 fIJ 

w .f    t# "   ~  c .d  

the th e

directly

mIn Inin ing g

cro cr oss ss-s -sec ecti tio on

plac pl acer erss

Cross-section

also .. .... .

have hav e lon long g be been en dis discus cussed sed..

forn fo rnia ia..

B.

time.

by the the wav aves es..

of

Uni nite ted d

black 

howev ever er,,

come

Dia iag gra ram mmat atic ic of beac beach h

( 

occur . .. ...

present

present

A.

offshore

at another. may

Survey at

min ine erals

poss ssib ibil ilit itie iess

the th e Cal alif ifo orn rnia ia

Gold Go ld-b -bea eari ring ng

Be ' 'Jc,"  J   c," 

be found

in the the

beach

doubtle lesss

erod er oded ed

far

coast

retr re trea eati tin ng

other

may

out

zone

bea each ches es

by t he he

so

Geodetic

are

bor ord der

and

(U.S (U .S..

is con conce cern rned ed..

the

offshore

min ine erals

econo nom mic of

stretch

to the the

that th at

in th the e

gold of the the

barren

returned

gold

that th at

the th e

suggested

up or down

in t he he

gold

say sa ys

idea

carried

bea each ches es the

that th at

an

are

and

the

··.to
foreshore

other

of

of

of the the

the

occur

Forr the Fo the most

sea,

a shift

of 

of Ore reg gon and Cali Cali--

som so me

time

process

proc pr oces esse sess

8):: 8)

This

of

are ar e tho those se

.

a for formerly

gold-bearing.

med edia iate te

de-

on bea beach ch pl plac acer erss

origin

bel elie iev ve

of t he he

wer ere e

wass de wa depr pres esse sed. d.

rde ee J . T. Pard

Circ Ci rcul ular ar

Som So me of th the e min iner erss

lin li ne is ofte often n

of th the e ge geol olog ogic ic

placer pla cers, s,

and

over ov er an and d over over ag agai ain. n.

and of th the e coas astt

fornia ia..

oc-

Beac Be ach h

whic ich h

impo im port rtan ance ce

may ma y be found found in repo report rtss

Nome, Nom e, Alas Alaska ka,,

wit ith h

beaches

coas astt

gra rav vels

at a time time when t.he co coas astli tline ne

The Th e be beac ach h

comes

zir irco con n,

of go gold ld an and d plat platin inum um..

two kin ind ds,

fou fo und overl rlai aid d

and

frag fr agme ment ntss In cu cutt ttin ing g

a dee deep per

or 'te 'terr rra ace ces' s'

its

sid ide es;

depo de posi sits ts channel el,,

at diff diffe ere ren nt

but erosion

they th ey ar are e prot protec ecte ted d

the th em

are ar e co cont ntin inua ually lly

of th thei eirr

'be 'b ench che es' valle ley y

keeps

ten te nds

a in-in to

in som some e wa way. y.

Bur uria iall is th the e most eff ffec ecti tiv ve may be pre res serv rve ed. oft fte en

been

lava la vas, s,

The

res re str tric icte ted d

mudd-fl flo ows,

v'a 'ay y in whic which h a plac placer er

name

'bu 'b uri rie ed

to stre strea ams

ash as h-f -fal alls ls,,

the th e Ter erti tiar ary y

Neva vad da.

howev ever er,,

Ther ere e

are, ar e,

buria bu riall

may be effected effected..

1.

cover erin ing g

coven:d

etc. et c.,,

ver ery y co com mmon dur urin ing g

channel'

7.

has

deeply

per erio iod d

othe ot herr

by whi whic ch

cond co ndit itio ions ns

8.

occu oc curs rs 2.

wit ith h

By cov cover erin ing g

in Ca Cany nyon on

By cove coveri ring ng

Cree Cr eek, k,

wit ith h

of a part of the the to oc occu curr larg la rger er

alo lon ng

rive ri vers rs

Trin Tr init ity y

grav gr avel el,, river

the th e

of th the e Si Sier erra ra

Tri rin nity ty,,

10.. 10

the

som so me

in the the

gla laci cial al

of

beac be ach h

(Suc (S uch h are ar e

(Ex (E xam ampl ples es

plac pl acer erss coast

as the the

of one one

geo ge olo log gic

proc pr oces esse sess

(In

Cal alif ifo orn rnia ia,,

Ne.v Ne .vad ada. a.))

a

with

exam amp ples

By sub submer erg gen enc ce the

deposited

to

in a nd nd

stre st reom om

grav gr avel elss

agis ag ist' t's s

Repo Re port rt

form

a

on the

in its its

landslide

lak la ke.

edge

may

Silt lt,,

san sa nd,

of this

bot otto tom m.

(Aft (A fter er

dam

up

a

of

of

ocean.

ond grav grave els

lake

will

Dav avis is,,

cover

Stat St ate e

the

Min iner era/ a/··

4.

with

cal alle led d

pour po ured ed

over ov er th them em.) .) wit ith h

By c ov overing

with

bel elo ow

(Ex (E xam amp ple less

of

By

cov co ver erin ing g

blocks,

this of

Desert Des ert

when

gen ener era al case ca se

by

lav ava a

the th e

stre st ream am

stre st ream am

are ar e

deposit itio ion n

case ca se

fou fo und

bed edro roc ck

esp es pec ecia iall lly y

in th the e

of

alo al ong

is

erosi er sio on.

the

west ster ern n

of dow down-fa fau ult lted ed

var ariious

Grea eatt

sort so rts. s.

Bas asin in

and an d

tim ti mes

Moja jav ve

tha th at

firm fir mly ce cem men ente ted d matt tte er,

tilt ti lt

of

one on e

mat ater eria ials ls

wit ith h

uplifted

bedrock

prior

allu al luvi vium um

of the the

  Repo Report rt

XXIX. XX IX.))

to

fault

deri de rive ved d faulting

grab gr aben en..

blocks.

Erosion

fro fr om th•• ot oth her erss . may

(Aft (A fter er

thus Davis ,

be

covers

Stre St ream amss

burred

State Stat e

(graben)

the cutt cu

under

Mineral Min eralogis ogist's t's

in the

the th e pla lac cer er,, in these

of infi infil~ l~

the th e more apt apt ways

the th e

from it its

Sie ierr rra a~ Nevada

amount.

thre th ree e

tim ti mes,

Locall lly y,

panied

rev re vers rse ed.

by lo loc cal

hundre red d

fee fe et.

fault ltiing

alo lon ng

whic ich h the

has

ste tee ep

the th e

in a giv ive en In th the e

even lie li e in

grad gr adie ien nt

may

tiII.ti ti ting ng is ac acco com m-

down-t -th hro row w

pla lac ce

and

escarpment

as wel elll as in ac actu tua al

face fa ce da data ta wil illl pe perm rmit it,,

been

to sev several is

on the the

In fo form rm,, th this is is a repl replic ica a

too to ok

sti till ll of

and an d ch chan ange ges s pos osit itio ion n

whi hich ch gr grea eatly tly

They sh shou ould ld

severa rall

channels

of a few fe fee et

easte tern rn

fact fa ctor ors s

(whe (w here re

or even

tilt ti ltin ing g

Oft fte en

Genera rall lly y

actio ion n

In-In

of the the ti tilt lt)) fr from om 20 or 30 feet feet

to the the ti tilt lt th the e ori origi gina nall

been

has

cha han nne nels ls

dir irec ecti tio on

fau fa ult ltin ing g

by li lim me and

the th e ac acti tio on

opp ppos osit ite e

pro roce cedu dure re.. blo lock  ck 

con co n-

by inte inters rstit titia iall

as

of the the Ter erti tia ary

to twic twice e,

are ar e im impo porta rtant nt fau fa u It

such

thro th roug ugh h

in form form

The gra rave vell

where th the e ancie ien nt

the th e

bemany

geol ge olog ogis ist. t.

modif ifie ied d

In pla plac ces

have

(Man (M any y

depth

burie bu ried d an and d

modif ifie ieq q

the th e grad gradie ient nt

grad gr adie ien nt

two

be

stre st ream am ch chan anne nels ls,,

Ne'  \1ad \1ada. a. Su Such ch di disp spla lace cem men ents ts

between

wel elll

Calif o rn rnia

gre rea ate ter. r.

place

down.d .dro rop pped

very

as

and an d mappe mapped d

The old lde er

been

reg re gio ion nal

to the mil ile e course

of

def efor orm mat atio ion n.

they th ey li lie e in the the di dire rec cti tio on

of

a

such

to gr grea eatt

coast

east ea st si sid de of th the e fa faul ultt pl plan ane. e.

sho sh owin ing g

region

form for m an and d attitude attitude..

crea cr ease sed d

regions regi ons.) .)

Diag agra ram m

anot an oth her er,,

discov disc over ered ed Surv Su rvey ey.) .)

or sili silica ca,,

solu so luti tio ons ns.. to have

The

is cho choked ed..

stream

surf su rfac ace e of

sed se di-

and an d thru thrust st

might

can any yons

the

of min minera rall

iro ir on car arbo bona nate te,,

origin ori ginal al

Neva Ne vada da.) .) the th e

wit ith h

defo de form rmat atio ion n

may be gre rea atl tly y

beco be com me

sedi·

syst sy stem ems. s.))

the

deposit its s

tent te nt may also also

burl rled ed

lake

or mudflo low ws

bas asee-llev evel el

by sed sedim imen ents ts

graben,

exam ex amp ples es,,

gravel

the

foot fo ot of th the e Si Sier erra ra

when

alon al ong g

of the the

first

bef efo ore

grav ave els

are ar e co comm mmon on

(Man (M any y

covered

'piipe'c 'p 'cla lay y',

By cov coveri rin ng

lower ered ed

6.

dep epo osi sits ts..

were

men ents ts

(Exa (E xamp mple less 5.

lok lo ke

channels

later

plac pl acer erss

mar arin ine e

to the the ex expl plor orat atio ion n

by ear earth th

tra tr ati tin ng

XXIX XX IX). ).

By cov cover erin ing g Tertiary

oth the er

active

this

riv iver er

(Off

and an d st stru ruct ctu ure

it is 3.

but

in su such ch a mann manner er th that at th they ey may be prof profita itabl bly y

Pla lac cer

val alle ley y

sedi se dim men ents ts

beac be ach h

form fo rmat atio ion n

g eo eologically

min ined ed,, is th the e ch chal alle leng nge e

mountai ain n

mar arin ine e

found.)

pres pr eser erve ved d

a

Mojav ave e

may ma y be look looked ed

elev el evat ated ed

of earth earth

To fin find d go gold ld-b -bea earin ring g

how

and

submerged,

pres pr esen entt

subm su bmar arin ine e channe chan nels ls have ha ve be been en by th the e U. U.S. S. Co Coas astt and and Ge Geod odet etic ic

showing

fan

exis ex iste tenc nce e

Nev evad ada. a.))

wit ith h

is

cov co vere red d

the th e

faulting.

neath

sketch

all llu uvial

Basi sin n

of th the e Si Sier erra ra

in plac places es

By cove coveri ring ng

of th the

11.

Ideal

with

to str strea eam m

Gre reat at

till ti ll..

area ar eass

fluctuating

thro th roug ugh h

are beli liev eve ed

and an d

cou co urs rse es

favo fa vora rabl ble e

ments.)

by the the fa faul ulti ting ng-d -dow own n

(Example less

Klam amat ath h,

examp exam ple

Coun Co unty ty..)

cau ca use sed d

syst sy stem em..

(An (A n

wit ith h

coveri ring ng '9. By cove elev el evat ated ed..

mote teri rial al..

str trea eam m

exam amp ples

forr in th fo the gl glac acia iate ted d as

lan la ndsl sliide

older

regio reg ions. ns.))

whic ich h By

as

(Many

Deser De sertt

in th the e Sie ierr rra a

mea ean ns

of

fai ail. l.

by

all of whi hich ch wer ere e

By co coveri rin ng mat ater eria ial, l,

the

Sierra

in ch chan anne nell-

of the ch chan ann nel el,, infl in flue uenc nce e

be und under erst sto ood

bef efo ore ac actu tual al

is takin ing g

min inin ing g

so far far as su surr-

min inin ing g is st star arte ted d

are rea a. Moja jav ve

and

Desert

tilt ti ltin ing g

grea gr eatly tly af affe fect ctin ing g

and

have

stre st ream ams

Gre rea at

been

ante an teda datin ting g

Basin

reg re gio ion n,

extr tre emely

acti tiv ve,

late la te Ter ertia tiary ry

and an d

early ear ly Qu Quate aterna rnary ry

perio pe riods. ds.

Rele Re leas ase e

The Th e fl flow ow of gr grou ound nd wa wate terr the th e forme formerr ch chan anne nels ls off, of f, ti tilt lted ed,,

thro th roug ugh h

scre sc ream am gr grav avel els, s,

of wh whic ich h ha have ve be been en bl bloc ocke ked, d,

or fold folded ed by ear earth th mov ovem emen ents ts,,

of co cons nsid ider erab able le

cons co nseq eque uenc nce e

cutt cu

is a fact factor or

when wh en it come comess to mi mini ning ng

such place placers. rs.

Wit itho hout ut so some me wides widespr prea ead d the th e qua uart rtz z al

was

vein ve inss

and decay fac fa cto torr

over

and sm sma all ll,, of go gold ld fo foun und d in plac placer erss

cam ca me fr from om vei veins ns rock ro ck,,

and an d ot othe herr min iner eral aliz ized ed

from fr om wh whic ich h

they th ey we were re re rele leas ased ed

weat athe heri rin ng

and

Tho Th ough

ori rig gin ina al

the th e

disi di sint nteg egra rati tio on sou so urc rce e

have been a dep deposi sitt prof pr ofit it,,

the th e riche richerr

resu re sulti lting ng

peri pe riod od of er eros osio ion, n,

ric ri che herr

to be be conc ncen entr trat ated ed may

be

belts

of

Nevad Ne vada a

been

the

fou fo und

world,

and

chan ch anne nels ls

pla lac cer ers. s.

thro th rou ugh

Sti till ll

cha ch ang nge es

dept de pth h of  oxidation,

vore red d

partic icu ula larl rly y

in

gold

the Sie ierrra

of Californ California. ia.

dis isin inte teg gra rati tion on

not

the th e ori rig gin inal al

farr fr fa fro om th the e pla lace ce

afte af terr

bein be ing g

carr ca rrie ied d

wher ere e

by runn runnin ing g

The Th e st stre ream ams, s,

flow fl owin ing g

morp mo rphi hic c an and d intru intrusiv sive e outt by gol ou goldd-be bear arin ing g to con onta tain in str tre eams over,

aur urif ifer ero ous

which

as

vein ve ins, s,

in

have

the

had

regi re gion onss

of met etaa-

rock ro ckss

thre th read aded ed

thro th roug ughh-

But

only

the th e

barren

covered

regi re gion ons, s,

To qu quote ote Li Lind ndgre gren n

Mou ounn-

were we re fo foun und d by ear early ly mi mine ners rs

volcanic

Sier Si erra ra an and d Kl Klam amat ath h

and an d Kl Klam amat ath h

thro th roug ugh h

gra rav vels ls..

mor ore e rece recent

lav la vas

area

to pa pass

betw twe een

the th e

have ha ve pr prov oved ed to be be barre barren. n.

(Miner (Mi neral al

again:

Deposi Dep osits) ts)

gre reat at

maj ajo ori rity ty

from fr om th the e weath weather erin ing g lodes,

shear

posi sitts

••..

  jo joints ts,,

with

dist di stri ribu bute ted d and

that

sou so urc rce. e.

inst in stan ance cess

Mos ostt

plac pl acer erss

m or ore

who says says,,

of

Sewar ard d

the th e

it

is

not

stated

in sc sch his ists ts

denied

is

are ar e not not that

in lni lni s mann manner er..

de-

The Th e

gold,

gold

more

howev eve er,

fa-fa

is on only

of de deep ep se secu cula larr

weat we athe herr-

as Al Alas aska ka,,

in the the se sepa para rati tion on

are ar e de desc scri ribe bed d

in his his ar arti ticl cle e

Peni nin nsu sula la

in deta detail il

by A.H A.H..

on the the go gold ld place placers rs

(U.S (U .S..

bre reak akin ing g

dow do wn

chan ch ange gess

of the the co const stit itu uen entt

one

of

this th is be beco com mes

the

dominates

rock

contained

pro rob bab ably ly towa to ward rd

the th e

Geolo log gic ical al

this is,,

inso in solu lub ble

Sur urv vey

free.

Thi s such su ch

of

but

usu sua ally alll al

the th e

process as fro frost st

the th e

is

mat ater eria iall .

if

the

com co mmon zed ze d

parent bein ing g

min iner eral alss

vein ve in

qua uart rtz z

min mi ner era a Is,

bro roke ken n

up,, up

ore body body,, .

suc su ch

hastened

by

and an d chan change gess

and

remai ain ns,

Min iner eral alii

read re adil ily y

sett free se free the the

inso in solu lubl ble e

easi ea si Iy deco decom mpose sed d

of

up th the e in inso solu lubl ble e

acco ac com mpan anyi yin ng

minerals,

mass,

og.en enci cies es..

is th ther eref efo ore

ingr in gred edie ient ntss

the th e

mat ater eria ials ls

too,

refr re fro oct cto ory

chem ch emic ical al

and an d

and an d

ind in dest strructib iblle

residual

quartz, most

rock ro ck

wit ith h th the e othe otherr

the

commo com mon n Iy ca carr rrii es es

very ver y

the th e

rel ela atively in

pure pu rely ly''

as pyri pyrite tes, s, set

of

inte in term rmin ingl gled ed

Clay

As a rul rule,

such su ch

allo al low win ing g

as

gold,

purely

the th e to be

physical

of tem tempe pera ratu ture re,,

rock ro ck const constit itue uent ntss

gold that

has

been

gold

rock ro ckss

deri riv ved

from

sup su pport rted ed may

is

by

in ra rare

the

by wea weather eriing bulk bu lk..

abundant

and an d mas massi siv ve

dist strricts

stat st atem emen ents ts

oft fte en

328, 32 8, pp. 12 125-1 5-127 27): ):

chem ch emic ical al

vein ve ins, s,

replacement the

Thi his, s,

wate terr-ta tabl ble e,

whic ich h

.... .. ..

bee een n der deriv ived ed

contain

in wh which

in cer certa taiin

of thes these e

be di st stri ribu bute ted d

rocks

is

of 

espe es peci cial ally ly

the th e

whic wh ich h ta take ke pl plac ace e

Broo Br ooks ks,,

agen ag enci cies es,,

of au auri rife fero rous us

It is of often

par arti ticl cles es

gold

hav ave e

irregular

the

vein inss

quar arttz .• .••.

pla lac cer though

or

regions

or small

as fin fine e

this th is

evidence,

many

seam amss,

gold go ld

and an d disi disint nteg egra rati tion on

zones,

In

dep epo osite ted d

of

and an d deg egre ree e

are ar e ab abun unda dant nt..

of gol gold d fr from om bed bedro rock ck

brea br eak k The

cli lim mate tes. s.

and an d large large ar area eass

The Th e pr proc oces esse sess

dep epo osi site ted d

wate wa ter. r. Th This is is ce cert rtai ainn-

igne ig neou ouss

to

and an d

of go gold is

it was fi firs rstt

ly true true in both both th the e Sie ierr rra a Ne Neva vada da tain ta ins. s.

sou so urc rce e

down

of  rain.

natu na ture re

weat we athe heri ring ng,,

dis isin inte teg gra rati tio on,

deep

by tro tropic ica al

one on e fa fact ctor or,,

Bullet Bu lletin in For the the most part rt,,

Rock Ro ck

reli re lief ef..

actio ac tion n

upo pon n,

are ar e

of  water-

of  vegetation, act cted ed

of ma mate teri rial al

than th an

or

meri me ritt oper operat ate e

dep de pth

grow gr owth th

rath ra ther er

sam sa me geo-

in wea weath ther erin ing g

effe ef fect ct

complete

larg la rge e

of go gold ld fr from om bed bedro rock ck..

of  temperature,

of  gravity.

the th e

and el eluv uvia iall

and there therefo fore re tabl e and

cond co ndit itio ions ns

in th the e vari rio ous

The

of pri prime me im impo port rtan ance ce

wher wh ere e pl plac acer erss

geol ge olog ogic ic

part rtic icle les, s,

of com comme merc rcia iall

rele re leas ase e

The Th e fa fact ctor orss

gold

per erm mit itte ted d

ing in g ar are e fo foun und d in the the no nort rth, h, in such such pl plac aces es

reco re con nce cen n-

grave gra vels. ls.

to exis existt

in the the ge gene nera rall solution,

It has has

form fo rm re resi sidu dua al

conc co ncen entra tratio tions ns

topo to pogr grap aphi hicc

is an ide ideal al

stre st ream am

into in to ri ric ch

form fo rmed ed

'hill 'h illsi side de''

wea eath the eri rin ng

tim ime e is a pr primary

accu ac cum mul ulat atio ion ns.

whic ich h

such su ch by ru runn-

rock ro ck

of

to con contr trib ibut ute e

pro roce cess sses es

comp co mpos osit itio ion n

by a more more activ active e

into in to

are ar e th the e mo most st im impo port rtan antt

hav ave e

case

a com compa para ra--

due du e to upl uplif ift, t,

cratio cra tion n f rom old older er go goldld-bea bearin ring g whic ich h

in ever ery y

of larg large e qu quan antit titie iess

foll fo llow owed ed

log lo gic

roc ro ck matr matrix ix..

indi in dica cate te

forr gold fo gold to be sw swep eptt

Thes Th ese e

surf su rfac ace e

the th e

and an d rele releas ase e

gene ge nera rall lly y

dep epo osi sits ts

thro th roug ugh h

may not

usua us uall lly y

of gold gold fr from om the the be bedr droc ock, k,

and an d th the ere

in bedbed-

A lo long ng pe peri riod od of de deep ep we weat athe heri ring ng,,

in sep separ arat atio ion n

cond co ndit itio ion n

zone zo ness

whic ich h coul uld d to tod day be mine mined d at a

plac pl acer erss

tive ti vely ly ri rich ch so sour urce ce..

of

orig or igin inal ally ly

perio iod d

inip in ipo ort rtan ance ce..

to pla plac cer

as

exte ex ten nsi sive ve

a lo lon ng

sour so urc ce

from fr om

in whic which h th the e met et--

to be be tr tra ansp spor orte ted d

Ther Th ere efo fore re,,

of extr trem eme e

ori rig gin ina al

of re rele leas ase e

firm fi rmly ly hel eld d - gold gold pa part rtic icle le s coul uld d

esc sca aped

wate ter. r.

proc pr oces esss

and an d ro roc cks - vaul vaults ts

ori rigi gin nal ally ly

not hav have nin ing g

The Th e pa part rtic icle less

of Gol Gold d fr from om Bed edro rock  ck 

The Th e

loss lo ss

cry rysstalli lin ne

as hig igh h

of  Science in th the e mat ater eria iall

and an d in th the e

3rd Seri Series es,, rep re pre rese sen nts

area ar eass

vol ol..

mass

material

to pure pu rerr

Merrrill, Mer form fo rmss 136 361 1]

Oza zark rk

amon am ong g amounts [Ameri [Am erican can

hass ha

in vol olu ume

sili si lice ceo ous to

more mo

it may may Journ Jou rnal al

esti es tim mat ated ed

Mounta tain inss

only fro from m 2 to 9 pe perr ce cen nt

Such Su ch red redu uct ctio ion ns

about in it its

of limes limesto ton ne

Pum ump pel elly ly

17,, p. 17

of th the

brought

reduction

by weat weath her erin ing g

according

as 99 per per ce cen nt.

lim li mes esto ton ne

rock ro ck mas mass. s.

in a roc rock

in a ve very

of mat mater eria iall

rocks,

than th an 50 per per ce cen nt, reac re ach h

changes

res esu ult

the th e

that th at

resi re sid dual

of the or orig igin inal al

nece ne cess ssar aril ily y

resu re sult lt

in

more

or

lesss les

may ha have centrati tio on

~f

of

constant

be

high hi

the

specific

lighter

to

On de decl cliv ivit itie iess

and hel help

to

sort

strat atiif

pro pr oce ceed ed

gravity,

settle

icati tio on.

Thi s

is

as long long as the the ro rock ckss

It

is

evident

agen enc cie iess

is

they

are

tive

to

that

pro rop portional

oper era ativ ive e. sea

rial.. rial

bri ring ng

Upli lift ftss

course sess,

and

erosion.

It

fav avo orab ablle those

the

is

evident

to

in

the the

which

whe hen n er eros osio ion n

abo ab out

land

is redu reduce ced d

pro roce cess ss

pro roc cess

and

sec ecu ular

to dis isin inte teg gra rate te of

length

of

must

of time

the

t he hese

in which

stab ablle

rela la--

permit

of resi resid dua uall

residual res

is

at

or

wat ater er--

removed that

of

the

mat atee-

of the the

quickly

conditions

mass

all

to

acti ac tiv vit itie iess

a wi II

..... ..

time

remain

amo am oun untt

acc ccu umulat atiion the

the th e

loose

a

mantle le''is

that

a

the

places

ren re new ewed ed

resi sid dual

in

have

acce ac cele lera rate te

period

of any any con consi sid der erab able le

than

will

in som some

mass

accu ac cum mula lati tio on

of su sub-

gold, of

effectiveness

for a long

con co n-

pro rod ducing

to th the

A la lan nd

level

bottom

con co nti tinu nue e

the

as

that th at

This

casse ca

former

the wil illl

materi ria al,

in th the

the

to

grav gr avit ity y

the

roc ro ck.

such

for

mat ater eria iall

par are ent

great ate er

minerals,

tendency

inso in solu lub ble

in the

mate terrial allly

material.. material rough

of an any y

diss sse eminate ted d

will

stances that

con co nce cen ntr trat atio ion n

bee een n

mater eriial near

by

are m os ost are ar e Sket etc ch

base-level

the

to a mini minim mum um..

gold

It seem seemss

that th at to topo pogr grap aphi hic c

whi hich ch ex exis iste ted d Nevada

duri du ring ng

were very fa fav vora rab ble

Rejuvenated swep sw eptt

and an d cl clim imat atic ic

the th e Eo Eoce cene ne

drain ina age

the th e im imm men ense se

at

hard ha rd ma matr trix ix,,

channel els; s;

and an d th the ese se,,

pre resser erv ved

by

cobb co bble le-w -was ash, h,

the

clo losse of gol gold d,

afte af ter, r,

ash, as h,

the th e per period

Tert Te rtia iary ry

becam ame e

sed se dim ime ents ts,,

volc vo lcan anic ic

of gold ld..

(lone) been

and an d

mined

gold

particles

quart rtz z

pebbles

and an d

Min iner eral al gr grai ains ns mech me chan anic ical al

gold go ld in pl plac acer ers. s.

of

and an d resi resist stan antt sand sa nds, s,''

are ar e wel elll

the min miner er.. A lo long ng li list st of ~h ~he e min miner eral alss box

conce cen ntr trat ate es

is

reco re cord rde ed

Bure Bu reau au of Mi Mine ness (I (Inf nfor orma mati tion on magn ma gnet etit ite, e,

ther th ere e

and ru ruti tile le), ), vine vi ne,,

epid ep idot ote, e,

osm os mir irid idiu ium m, and an d

cop co pper, watch wa tches, es,

as

Circ Ci rcul ular ar

mona mo nazi zite te,,

cinn ci nnab abar ar,,

tung tu ngst sten en

cass ca ssit ite eri rite te,,

well we ll

as

bir ird d-s -sh hot,

bull llet etss,

foss fo ssil il))

the th e re rem main inss

hoof ho of an and d ir iron on sh shoe oe na nail iled ed som so me of th the e pla lac cer erss repr re pres esen enta tati tiv ve ancien anc ientt

on th the e

Sta tate tess

(ilme (il meni nite te oli li--

plat pl atin inum um,,

min iner eral alss

(wol (w olfr fram amii te

coru run ndum,

dia iam monds,

amal am alga gam m,

hobnails,, hobnails

stream str eams. s.

of wha what

penknives,, penknives

thou th ough ghtt

it was was an

hin ind d le leg g wit ith h

to it. it. Wha hatt may may be fo foun und d in was

lying

above

a bend

in th the

ente en tere red d. in

cla lay y

in the

Fin Fi nel ely y

l en enses

layer erss

of  

('f 'fa alse

of qu quan antit titie iess

may not ot,, deposi site ted d

of ma magn gnet etite ite

fine fi ne go gold ld pa part rtic icle les, s,

mag agn neto tom mete terr

make ma kess

a dif diffi ficu cult lt

To the ge geop ophy hysi sici cist st,,

however,

is

The Th e de dete term rmin inat atio ion n prox pr oxim imat ate e use sed d

rela re lativ tive e

in th the oil fi fie eld lds. s. nott ye no yett

this th is in inte tere rest stin ing g develo dev eloped ped

hass ha

corr co rre ela lati tio on

give gi ven n

fie fi eld

techn tec hniqu ique e

eff ffe ect

to effe effec cti tiv ve

of heavy heavy min iner eral alss

to rhe rhe trac tracin ing g

been be en

a str tro ong

a god godsen end d

ex-

and an d th thei eirr ap ap--

been be en exten extensi sive vely ly

of se sed dim ime enta tary ry

The sam ame e met eth hod

well we ll be app appli lied ed hass ha

hav avin ing g

perc pe rcen enta tage gess

in subs subsu urf rfa ace

asso as soci ciat ated ed

of re ressea earc rch h

of cha chann nnel els. s.

cons co nsid ider erat atio ion n

is open

beds cou co uld

Thou Th ough gh it

in Cali Califo forn rnia ia,,

forr st fo stu udy

wit ith h a wel welll-

depo de posi site ted d

and an d as asso soci ci--

avail av ailab able le..

met etal alli lic c

of the the mo mode dern rn Fe Feat athe herr

of a mule mule's 's

of to tod day

san sa nd

of any min ine era rals ls

ploration.

chro ch rom mit ite e,

limon lim onite ite,,

Rive Ri verr wa wass on once ce fo foun und d (a (and nd so som meo eone ne

interbedded

the th e pre rese sen nce

The Th e so sour urce ce ate ted d

in the gr grav avel elss

a tri trib buta tary ry

prob pr oble lem. m.

gene ge nera rall lly y

and na nails. ils.

Buri Bu ried ed de deep eply ly anc an cie ien nt

the th e

6786 67 86). ). Be Besi side dess

mine mi nera rals ls

qui uick ck si sill ve ver, r,

wher ere e occur

meta me tallu llurg rgic ical al

know kn own n to

Unit ited ed

hemat atit ite e,

pyri py rite te,,

sch sc heel elit ite e),

galena,, galena

zirc zi rco on,

to

foun fo und d in sl slui uice ce--

by th the e

are ar e fo foun und d tit titan aniu ium m

gar arn net,

- on on

del eltta

where

gra rav vel,

acco ac com mpa pany ny

'bla 'b lack ck

of mag magne neti tite te,,

channel

its

bedrock').

with wi th ex extr trem emel ely y

dest de stru ruct ctio ion n

The Th e so-ca so-calle lled d

the

and an d

indicate

and an d lava lava fl flow ows. s.

that th at ar are e very very he heav avy y

made ma de up pr prin inci cipa pall lly y

crosses

and

Min iner erals als

and an d chem chemic ical al

cha ch annel

The in

at the the poin pointt

divided

The Th e pr pres esen ence ce Asso As soci ciate ated d

Tert rtiiary

sea.

stre st ream am

buri ried ed

mass sses es

brec br ecci cia, a,

of an earl early y

free fr eed d fr from om the

into in to th the e ea earl rly y soon

lak la ke

of

has

stre st ream am,,

peri pe riod od in the the Si Sier erra ra

forr rh fo rhe e re rele leas ase e

qua uant ntit itie iess

encl en clos osin ing g

cond co nditi ition onss

map

Eocene

the th ere refo fore re,,

be

by the the more more

wit ith h

of the the miner mineral alss

the th e gold

partic iclles

lies

in the the

whic wh ich h th the e st stre ream am ha hass fl flow owed ed..

The Th e so sour urce ce

pla lati tin num,

gener era all lly y

belt ltss roc ro cks,

and

dia iam monds

of serp serpe enti tin ne whil ile e

is

and rela relare red d

garn rne et,

ilm il menit ite e

and an d

rock ro cks, s,

cass ca ssit iter erit ite, e,

and an d sch schee eelit lite e

have ha ve th thei eirr so sour urce ce

in gran granite ite

att ttri rib bute ted d

to

ign ig neous

mag agn neti tite te

and an d mo mona nazi zite te,,

pegm pe gmat atite itess.

over

of ch chro romi mite te,,

ult ltra rab basi sic c

come co me from me meta tamo morp rphi hic c wolf wo lfra rami mite te,,

rocks

mig igh ht zirc zi rcon on,,

woul wo uld d pro proba babl bly y

The Th e

proc pr occe cess sses es

of tran transp spor orta tati tion on

of gold in a stream

are aptly

and an d depo deposi siti tion on

stated

by Mr. Mr. Brooks

(p. 128): The

tran anssporting

vel elo oci city ty,,

whic ich h

vol olu ume

and an d

ment,

the

ero er odes es..

norr no

usu sua ally be going

ano an other. reac re ach h

a vari varian antt

var ary y

of its

a

acti ac tiv vit ity y

been be en

same

stream

is of

is

gra rad die ient nt,,

ished ish ed,,

so

valley

ero rod ding,

the th e

kin ind d

forr the fo the

takes

place

a str stream

either

by th the

it

nei eith ther er and an d

deposi sittion

and

erasion

mat ate erial

in

within

in a downst stre ream am

are ar e

and an d mak ake e

sed se di-

volu vo lum me

that

moved

this th is

wit ith h

Gra rad die ient nt,,

its

on its its

underl oaded,

esta es tab bl

stre rea am

of

is cons consta tant ntly ly

sorti tin ng

it

pla lace ce..

part

All mo move vem men ents ts

or les esss

ha s

in th the

by the the

is over overlo load aded ed

When

take ta kess

on in on one

is dependent

dete de term rmin ined ed

dropped.

equ eq ui Iibr Iibrii um

When

dir irec ecti tio on.

is

deposi dep siti tio on

load

of a str stream

When a stre stream am

excess

may

more

is

load lo ad..

When

ero er osi sion on

power

acco ac com mpli lish shed ed

con co nce cent ntra rati tio on

by

of the the

heav he avii er pa part rtii c Ie s. Deposition is de decreas ase ed, by a chan chang ge

of

resulting

in

with wi th th the e

othe ot herr

that

placer

bedrock

gra rad die ient nt..

may

find

det etri rita tall

mat atte terr

hass ha

tak ta ken

are re,,

a ru rule,

not

forrmed fo

bed-rock river for

surface

bars it

is

is

chec ch ecke ked d

analo log gous

dropped

to

deposition

the

by the the fo form rmat atio ion n

of the the ri rive verr

its

where

of edd eddie ies, s,

of

of

the

due du e to the the

of   in the

gold

in str stream

velocity

in in

bed edss,

current

is

ineq in equa uali liti ties es

floo fl oor. r.

A fu furt rth her conn co nnec ecti tion on

stu tud dy

of this this

sub su bje ject ct

is made he here rein in in

with wi th th the e mor ore e deta detail iled ed

anal an alys ysis is

of str strea eam m

action.. action When th the bed of a st stre rea am it is cal alle led d

of the the word rd.. Late terr on an agg aggra rad ded the th e st stre ream am

in its its his isto tory ry

bed be d of gra rave vell

gra rav vel elss

mat ater eria ials ls,,

beco com me

the th e

this th is ne new w co cove ver, r,

stre st ream am

call ca lled ed

'fal 'f alse se

are ar e no norm rmal ally ly de depo posi site ted d whic wh ich h is ca call lled ed to wh whet ethe herr valle ley y lyin ly ing g mis ised ed,,

rock ro ck fl flo oor

in the the tr tru ue sen ense se

the th e st stre rea am or othe other

cov ove ere red d

may fl flo ow

sed se dim imen ent. t.

If 

wit ith h vol olca can nic

or

is obli lig ged bedr be droc ock. k.''

to flow flow ov over Gold Go ld par parti ticl cles es

or 'fals 'false e

bedr be droc ock' k'

a superfic icia iall

layer

tuff tu ff,, or some some su such ch im impe perv rvio ious us

prev pr evio ious usly ly

depo de posit sited ed

ther th eref efor ore, e,

of gold gold-b -bea eari ring ng

grav gr avel el..

of clay,

mate ma teri rial al

over ov er--

It is re read adil ily y

do not not ne nece cess ssa ari rily ly

lie li e

on bed bedro roc ck,

cour co urse sess

at all all.

of grave gravels, ls,

incl in clud udin ing g

the th e tr true ue be bedr droc ock, k, lie li e at rel relat ativ ivel ely y hori ho rizo zons ns..

remn re mnan ants ts high hi gher er

the th e old lder er an and d

In som some e

case ca ses, s,

whe here re

inst in stea ead d grav gr avel el

a new new ag agg gra rad ded

gold go ld part rtic icle less

wil illl

bedrock.

The

complexit ity y

pro roce cess sses es

is

of

the

reac re ach h

appar aren ent; t;

engineer

laye la yerr

a posi positi tion on of

the

so also also

who

bed ed,, re re-mas asss

depo de posit sited ed

wil illl be th that at most of the the

attempts

ver ery y

nea earr

history

of

tru tr ue the th ese

are th the e dif iffi ficu cult ltie iess to do a fair

job o f  

sampling.. sampling forr th fo the e Bo Boul ulde derr

Dam Da m a sa sawe wed d

plan pl ank  k 

of lumb lumber er wa wass fo foun und d 60 feet feet de deep ep,, "ly lyin ing g

unde un derr gr grav avel el

on the edg dge e of th the e in inn ner gor org ge,

that th at it coul uld d

n.ot hav have e buria bu riall cas ase e

rea re ach ched ed

durin du ring g

in any any im ima agi gin nab able le

riv ive ers

may be sti tirrred soap so apy y

mix ixtu ture re

flood flo od." ."

by

This Th is

sho sh ow th that at th the e dep epth th of buri ria al

does

depo de posi sitt.

acti ac tion on gi give vess

way exc xce ept

some so me compa compara rati ti ve ve1y 1y rec recen entt

and an d man any y oth the ers

by rec recent

a pla place ce

not

necessaril ily y

Dur urin ing g

hig igh h

up and even of hea heavy vy

mean

wat ater er,,

the th e

bould lde ers

rock ro ck de debr bris is

the th e go gold ld part partic icle less

tha th at

a

forr the ac fo accu cumu mula lati tion on who hole le mass

flo fl oated

in th the

and an d wa wate terr .

This

a cha chanc nce e

to wor work k thei theirr

way wa y to towa ward rd th the e bo bott ttom om of th the e mas ass. s. For

tho th ousa san nds

of 

size si zes, s,

of yea years rs

riv ri ver er-s -slu luic ices es

from fr om nugg nugge ets of the the

of be bedr droc ock k

Sie ierr rra a

pended

by air-fil ilm ms,

tin iny y

of at at lowe lowerr

surf su rfac ace e

of the the wa wate terr.

Extr Ex trem emel ely y

were swep eptt

easily

by to torr rre ent ntss

carried: scales

thro th rou ugh

were ·dropped

alon al ong g

Neva vad da.

will wi ll

is depo deposi site ted d

of gold gold of var var--

to flo flour go gold ld,,

are

cle lear ar down to

most

part pa rtic icle less

ticles

of the the older older ch chan anne nels ls

posi po siti tion onss

conc co ncen entra trate ted. d.

wil illl sti tirr up the the ent ntir ire e

on top top,, and th the e fi fin nal re ressul ultt

and an d lo lodg dged ed in the the ri riff ffle less

cut utss

indica catting

1898.)

the th e go gold ld-b -bea earin ring g

dire di rec ctl tly y

If th the st stre ream am

river,

to be beco come me

Rept .

form fo rmin ing g

of th the e st stre rea am

iou io us

low lo wer ch chan ann nel s, and may not fo foll llow ow th the e dir ire ect ctio ion n thei th eirr

dee eepl ply y

chan ch anne nell s, bu butt th the e up uppe perr on ones es abo ab ove

a

sursu r-

that th at th ther ere e may be tw two o or more more tier tierss stre st ream am

likel lik ely y

18th 18 th An.

  ju juven ena ati tion on

of th the e

acco ac cord rdin ing g

the th e be bed d is th the e tr true ue ha hard rd ro roc ck fl flo oor of th the e it is

of

grea gr eatt pe perio riod d of tim time e ha hass el elap apse sed d

on or or near near th the e be bed d of th the e st stre ream am,,

'bed 'b edro rock ck''

or whether

volc vo lcan anic ic

is th the e act ctu ual

'be 'b edro roc ck'

course

are ar e most most

U. S. G. 5.  ,

Spur Sp urr, r,

In exc excav avat atin ing g

of the the vall lley ey,,

oth the er

gold go ld partic particles les

(Aft (A fter er

the th e

the

plac pl acer erss

irreg egu ular ariities

concentration

illustrate

down of

exte ex ten nsi siv ve

of

wher wh ere e

to

how ho wev ever er,,

deposition

thou th oug gh

The

laid

in ineq equ uali litties

because

or

of grad grade, e,

is

considerable

plac pl ace, e,

alone.

gold

Diagram

velocity

in vo volume

be rem remem embe bere red, d,

lodgmen entt no

the

is a chan change ge

the

It mu must st

where

when

changes

veloci citty,

sedi se dime ment nts. s.

gold

periodic

Wher ere e th ther ere e

diminished di

surface

as

in

the th e natur natural al

Fla latt tten ene ed

parpa r-

sometimes,

sus-

even

float

on th the

fine fi ne gr grai ains ns

of go gold ld

the th e ca cany nyo ons

and an d out out

In th the e pr pres esen entt

into in to th the e Gr Grea eatt Va Vall lley ey.. where th the ey in fa fals lse e

are fo fou und,

bedr dro ock,

volc vo lcan anic ic

whic ich h

very

high

time ti mess

caus ca uses es

specific

this th is he heav avy y

it is ca cau ught

meta me tall the th e

delta

fin ine e

bedro be drock. ck.

'fa 'f als lse e

bedro rock ck''

gold

one

of

has

Once

gre reat at

mounta taiin

or a st stil illl

by that that str tre eam

may

dif iffi fi--

be

lay la yers rs..

canyon

and

Dia iagr gram amm mat atic ic

are

and

The

may ne never

on top top of cl clay ayey ey,,

stir st irri rin ng

acti tio on

cany ca nyon onss

duri du ring ng ti tim mes of 

gold go ld to re reac ach h

fou fo und to

bedr be droc ock, k,

does do es no nott

B.

The Iitii c Iit andesit andes ite e

  Lin Lindg dgre ren, n,

para rad dox

[stat ate ed

these

min iner eral al

degr de gree ee

and an d ow owin ing g

to its its

pre resser erv ved ed..

trouble

minute

gold

diff di ffic icu ult

are ar e

without

Dr. Lindgre ren n],

and an d most

to a hig high h

par artticl cle es is

U.S. U. S.G. G.S. S.,,

Alth Al thou ough gh they th ey

A piece

div iviisi sib ble

par artticl cle es

can ca n

intto in

dif iffe fere ren nt

tumb tu mble le

alon al ong g

weld lde ed

some so me pe peop ople le that

the

lod lo des,

in the the

tog to geth the er

largest

2000

abou ab outt

whic wh ich h

tho th ose

whose not

tim ti me.

exis iste ten nt, of

a

sou so urc rce e

in

the and

Deep

Blue

benches

of

rep re pre sen sentted

by

c;

tuff tu ff-b -bre recc ccia ia,,

andes and esit ite e

a;

lead, the

rhyo li litte d.

P.P. P. P. 73 73.) .)

Dia iagr gram am show sh owin ing g the th e place of greatest ero s i on on on the bend of a ri rive ver. r.

higher

solutio ion n shown

to

have

come fr from

The Th e mo more re roun rounde ded d gone go ne th thro roug ugh h

piec pi eces es..

more mo re

Thes Th ese e

form fo rmss ha have ve

show sh ow--

prob pr obab ably ly

nott no

pla lac cer erss,

and an d

many ma ny re reco conc ncen entr trat atio ions ns,, degree

of

fineness

to

such the th e

a long removal

acti ac tion on of sur surfa face ce reprecip ipiitatio ion n be

com co mmerc rcia iall lly y.

the th e gold period

of

of  

allo loy yed

wate wa ters rs.. gold

in th the e

rare

or no non-

On the the oth the er

hand,

in som some

channels,

themse the mselve lves. s.

of

tha th an

exceedingly thin

are fo fou und dep epo osi site ted d

gold go ld part particl icles es

Diag Di agra ram m tion s of tio suction river. like li kely ly to in the than in eddy.. eddy

of gold gold may be bro rok ken piec pi ece. e.

for

due

and

as

hass sh ha show own n

is near by, or in whic which h

be

it as as

nuggets ts,,

the th e more anc ancie ien nt

deposited

may

is

gold

unde un derg rgon one e

of

th.e Te Terti tia ary

mar arc casi site te

peri pe riod od

and

stat st ate. e.

silv si lver er by the the diss dissol olvi ving ng gravels

of

crys cr ysta tall llin ine e

have ha ve

been

This

The

cobb co bble le,,

rhyo rh yoli lite te

by d.

part pa rtic icle less

Lind Li ndgre gren n

than th an th the e ro roug ughe herr

fou fo und tha that

gold

diff di ffer eren entt

have ha ve pr prob obab ably ly

farr in the fa the 'f 'fre ree' e'

conta taiin

The Th e

andesit ite e

worth

parts ts,,

hit itti tin ng

to form form la larg rge er

Par arti ticl cle es

nugg nu gget etss

It is als lso o

thos th ose e

by sto stones

from fr om an anot othe herr

ing in g the origi origina nall trav tr avel eled ed

part rt..

represent

inso in solu lubi bili lity ty

of gol gold

and an d may be ham ham--

stre st ream am,,

masses

not pla lac cers rs..

or fl flat atte tene ned d

has

sha hap pes

are ar e pr pron one e to belie believe ve..

down do wn,, ho howe weve ver, r, knoc kn ocki king ng

probably

channel are

Sierra b to to d 

is at the the

read adii Iy be be recognized

gold go ld is ve very ry ma mall llea eabl ble, e,

into in to

are not

older

and

in

the

Eocen ene e;

to rec reco ove ver. r.

a pa pan. n.

mere red d

mos)

deposits

epoch

four fo ur pri princ ncip ipal al in

a represe sen nt

by c an and d the

showing

Placerville. b;

for th the e

the th e

deposition

younger

stages

intter-r in -rh hyo tuff tu ff,,

gra rav vel elss

successively

Diagram

show sh owin ing g

gravel

deep

is rep repres ese ented

At th the e apex of this fan or deposit ite ed,

Tertiary

The

Mio ioc cen ene e

in

cro cr oss ss-s -sec ecti tion on

of

Nevad ada a.

body of wate water, r, are ar e dep epo osit ited ed

may ma y be depo deposi site ted d

It

the th e ea easi sies estt

It is divis divisib ible le cen entt

to wo work  rk 

in th the e delt lta a.

By an add add

one

fact fa ctor or wh whic ich h

even ev entu tual ally ly

stre st rea am

its

countr try y

whic wh ich h pe perm rmit itss

tim ti me

or

SIX

epochs

in rugg rugged ed mo moun unta tain inou ouss pla lac ce

gold,

A.

lea le aves

carr ca rrie ied d

reach rea ch

fin fi nest

of 

it up agai again. n.

the th e form of a fan or delt lta a.

the

lay la yer erss

wher ere e it may may si sin nk no fa fart rth her er..

a more more le lev vel

the th e mate materi ria als

sam sa me

cau ca ught

wit ith h th the e ra rati tio o in incr crea easi sing ng

resi re sist stan antt

When a stream

tak ta ke

of cla clay yey

is th the e pr prim imar ary y

on be bedro rock ck,,

culty cu lty in pick pickin ing g

floo fl oods ds,,

easi sily ly

gravi ty of

that th at of quar quartz tz,,

itss way to a poin it pointt

occu oc curr

bee een n

con co nsi sist stss

to ni nine ne ti time mess un unde derr wat ater er,,

ente en ters rs

hav ave e

grou gr ound ndss

tuff  tu ff .

The seve se ven n

the th ey

dred dr edgi ging ng

crusts

on the the

of

pyrit ite e

surf rfac ace e

or

of th the e

Diagra ram m to sh sho ow how a suction eddy is formed in a river. (After Thomas and Watt, see Ries and Wat atsson, Eng. Geo!.)

to show show po posi si-pre ress sure sure and eddies in a Gold is more be de depo posit sited ed suction eddy the pre resssu surre

disc di scus usse sed. d.

Phys Ph ysic ical ally ly,,

loc lo cat atio ion ns

wher ere e

port rtin ing g

away

rich ri chne ness ss the

of

the

this th is

abiilit ab ity y

the

furn fu rnii sh shed ed

cert ce rtai ain n

str trea eam m

is

as

a

rich lo lode de The tially

vertical

successian

of

bott bo ttom om set set,,

beds be ds..

section

of

s tr trata:

(A)

( Af Aft er er

a

delta,

showing

t op opset,

G ililb er er t,t,

(B)

the

foreset,

U. S. S. G. G. S. S.,

5 th th

t yp ypical

spec sp ecif ific ic The Th e

and An .

(e)

Re pt pt .,.,

1883.)

can ca n

which

not

the th e

conc co ncen entra tratio tion n esse es ses s

deposi sitt

in tha that it is a spe specia iall

due du e to sever several al

case of 

fact fa ctor ors. s. per

com co mbi bini ning ng na natu tura rall

proc pr oc--

whic ich h wer ere e al alll in favo favor of th the e ac accu cum mul ulat atio ion n

the th e on one e de desir sired ed

min iner eral al..

tion, tio n, depos depositi ition on,,

stream stre am

fac fa cto tors rs

patte pa ttern rn,,

cou co urs rse e

so

the

contr tro ol

stre st rea ams

of min iner eral aliz izat atio ion n;

at the the su surf rfac ace e

of th the e

Thr hree ee ex extr trem emel ely y

(1)) Str (1 tru uctu tura rall

tha th at

transp tra nsport ortaa-

and an d ret reten entio tion n

been be en di disc scu uss ssed ed.. are re::

of the the zo zone nes s

disi di sin nte tegr grat atio ion n

release rele ase,,

reco re conc ncen entra tratio tion, n,

gol old d ha have ve al alre read ady y import rta ant

Sourc So urce, e,

of 

of the the

reju re juv venate ted d

was ash hin ing g

of the the re rele leas ased ed

wher wh ere e

flo fl ow of st stre rea ams

rar arel ely y

a me mere

curr cu rren ence ce natu ture re

of has

ai iza izati tio on, pat atte tern rnss, forrmed fo ed.. thes th ese e

and th the e ra rap pid

gold go ld in into to st stre ream am ch chan ann nel els. s.

bes esto tow wed rap ra pi d

rock

a rel relat ativ ive ely

seve se vera rall of

it is

fav fa vor orab able le the lar arg ge

and amo am ount

in thi thi s idea ideall fact fa ctor orss

cons co nsid ider erat atio ions ns in

spe sp eci cial al

rat ath her

plac pl acer er the th e

fact fa ctor orss.

advan anta tag ges

deca cay y,

imp im por orta tant nt

gen ge ner eral al gold

in an imp impor orta tan nt

coin co inc cid iden enc ce; sever sev eral al

But ev eve en

The Th e tio ion n

of gold gold

far arttuita tau us

of gol gold

whic ich h

the

plac ace er

is

whe here re miner er--

and an d whe here re

hav ave e

the th e

bee een n

rolled

down rati ra tio o

allo al low w

the

rock

and

quir irin ing g

or

eroded.. eroded easi ea sily ly

accu ac cum mul ulaa-

The

any

that th at

of

place pla cerr

that th at

carrrie ca ied d

and

specific

gravity

of  

butt un bu unde derr

This Th is

larg la rge e

it

which

mor ore e

cond co ndit itio ions ns

gold go ld th than an

mate terrial of

be

a har hard d,

stream stre am

remains,

which

re-

loca lo catio tions ns..

or less

more

tran tr ansp spo ort rtat atio ion n,

ther th ere e

con co nta tain inss

mat ater eria iall

high hi gherer-gr grad ade e

sup su pplie iess

difdi f-

to bed bed--

may occu occur, r,

more

of low low-g -gra rade de

also al so

it

to

wat ater er

grav gr avit ity y way

to ne new w

less

furn fu rnis ish h

its

Here

mat ater eria iall

may

reduced in ve velo locc-

part rtic icle less

of

form fo rmat atio ion n

ano an oth ther er

miner eral al

an abu abundan anc ce and

When a

is bei ein ng

of gol old d

gold

gold.

redu re duct ctio ions ns

dep de pos osit itio ion n

A de deca caye yed d

of 

wi II be form formed ed

to work

to remove

are ar e

somewhat

a

therein.

in-in

immed edia iate tely ly

or jo join inss

grav gr avel el,,

tim ti mes es..

of   en-en

the th e ve velo locc-

cha ch annel elss

turn tu rns, s,

hea eav vy

source

period furt fu rthe herr

of wat ater er,,

are ar e

been

quick ckly ly

crevices ero er osi sio on

and an d

to inc incre reas ase e

has

oft ften en

cond co ndit itio ions ns

a l on ong

the th ey

of th the e

nin ine e

gold

a maj ajor or

deco com mposed

bala ba lan nce ced d

Gold that th at

abou ab outt

exce ex cess ssiv ive e

more

grav ave el

canyon.

the th e

into

In or orde derr

and

of

When

tilt ti lt

eros er osio iona nall

Thes Th ese e

gold

mas asss

Wit ith h

how ho wev ever er,,

reg egiional

of th the

have

gold ld..

han ha ndi dica cap p.

of con conce cent ntra rati tion on

occu oc curr.

six si x ti time mess

perm rmiits

may be be of 

curr cu rren ents ts

beco be com mes

fer ere ence

zone zo ness

of

volu vo lum mes

ten te nd

dee eepe pens ns,,

velo ve loci citties

fro fr om the the

be

fre req quen entl tly y

eddy ed dy

ity imm immed ediiat atel ely y sep se par ara ate

must

be ass assu ume med d. favo fa vorr

wat ater er

and

may be so som me-

to re rew wor ork k

deposit itss out ut,,

cert ce rtai ain n

the th e

str trea eam m

fav fa vora rab blen enes esss

specif spec ific ic wide wi dens ns

appr ap prox oxim imat atel ely y

con co n-

In regio region ns

wel elll-d dev evel elo oped

mus ustt

loca cati tio ons

dep epos osit it

of ext exten enssiv ive e

case ca se,,

forr fo

cany ca nyon on

there reiin.

grad gr ade. e.

the th e

bec ecau ausse

to may

of gr grad ade e,

chan ch anne nels ls,,

and an d

in the the .sh sha ape

howev eve er,

that

of w at ater,

seri se rio ous

as do in incr crea ease sed d

var aria iati tio ons

inte in tere resst,

resp re spo onsi sib ble

this th is Acc ccum umul ulat atio ion n

Local

of go gold

grav ave els

to provide

fact fa ctor orss

upo up on

gold

lim li mit itss

anci an cien entt

tend te nd

t~at

effe ef fect ct

30 to app appro roxi xima mate tely ly

the th e orig origin inal al

upl plif ifts ts

as both both of the these se

the the th e

thes th ese e

so as

mean anss

amo am ount

deposi sittio ion n

accu ac cumu mula lati tion ons, s,

balanced,

bein be ing g

app ap pro rox xi-

rel elat atiionsh shiip

fau fa ulti tin ng

the

from fr om ve velo loci citi ties es

quantity

wit itho hou ut

that th at

dep de pos osit its, s,

This

of

from fr om

of th the e

vari va ries es

abru ab rupt ptly ly

the

and

of mat ater eria iall

an en enor ormo mous us

fro fr om

rang ra ngin ing g

modi mo difi fied ed

Slig Sl ight ht

rich ri ch plac placer er

wat ater erco cour urse se,,

rock ro cks s

the

is esse essen n-

water

waterr wate

vel elo ocit ity y.

channel,

gra rad des

rich ri ches estt

con co nce cen ntr trat atio ion n.

(2)) Dec (2 ecay ay and

prio pr iorr to er eros osio ion; n; (3 (3)) A cha chang nge e in th the e cy cycl cle e of erosi erosion on,, causi sin ng

the th e

run alo lon ng th the e

of th the e min iner eral aliz ized ed

of

uncoveri rin ng

mat ater eriial alss

much

of flow flow,,

rem re member

be well

stre st ream am

to its its

of t he he of

rel ele eas ased ed

or red reduc uced ed

cons co nsid ider erab ably ly

ity.

efficiency

than

i~ a com complex

of t he he

the th e

must

most

the

an ap appre reci ciab ablle

cond co ndit itio ions ns

one

asmu as much ch

whi hich ch

rich ri chne ness ss

rath ra ther er

transport

A grad grade e

have ha ve

Forr Fo

lod lo de'

pres pr esen ence ce

have ha ve

mi Ie wi II fav favor

incr in crea ease sed d

must

earl ea rly y

the th e

part pa rtic icle less

of the the

rang ra ngin ing g

or be

size

cons co nsid ider erin ing g

merc rcia iall min ine era rall

rela re la--

The Th e the th e

pow ower er

chan ch ang ges

of wat water

appr ap pro opr pria iate te

wor orrh rhy y of min minin ing g is li like ke an any y ot othe herr co com m-

gold at

gene ge nera rall

with wi th

to

of the the

tra ran nsp spo ort

stre st ream am

and

ft.

and

of the the go gold ld,,

velocity

power

easily

velo loc cit ity y

wha hatt

A pl plac acer er

six si xth powe po wer, r,

those

100

grav gr avit ity y

vel elo oci city ty

whic ich h

othe ot herr

upon up on

power,

stream.

to tra tran nsp spo ort

the

tran tr ansp spor orti ting ng

as the the

shape,

not onl only y

or 'mot 'mothe herr

dev eviice

upon

tran tr ansp spor orti ting ng

Ideal

to The

dep epo osi site ted d

the

more

con co ncen enttra rati tin ng

tra ran ns-

settled.

On th the e

How owev ever er,,

due

of a str strea eam m

smal sm alll

The

the

'led 'l edge ge''

as a sourc source e

abili lity ty

and an d

entter en

to

plac pl acer ers. s.

have

dep de pen end d

to ho hold

the th e

the

insu in sufffi fici cien entt

tran anssporti tin ng

impo im port rtan antl tly y,

dependent

mat atel ely y

that

of

sources

perhaps

deposit ited ed,, bec eco ome

in su such ch

depo de posi si ts ts..

carried.. carried even ev en

bedro rock ck

rich ri ch

is si simp mple le;;

ther th eref efor ore e

loss lo ss

most mo st

zone zo ness

placer

wil illl

soug so ught ht

of min miner eral aliz ized ed

area ar ea

gold

gold

unti un tiri rin ngl gly y

of a

of

this th is

of the the

of

min iner erss

of

been has

particles

butt also, bu also,

tionship

has

stre st ream am

of the the de dep pos osit it

poi oin nt,

phenom phen omen enon on

gold

the the

complet eten enes esss

on the the

~ -----~--' ---'-..------.-• . . . _ =:-~ -~--~  _ . ~ - -:-:-- _- .:: :.: : = ---- - - - - -:-::: : : . : . -..:~: _   _ " - ~ - --~~ -.=: --

the

power

carry

the th e

easily coul co uld d deposi dep osit. t.

gravel gra

for

prov pr ovid idin ing g

that th at

ove verl rlo oad adin ing g

crea cr easi sin ng

or cho chok kin ing g

wote terr

veiin ve

syst sy stem em

gold

than

vol olu umes es..

wil illl

hav ha ve

one

A fu furt rth her rock

to

acti ac tio on bedr be dro ock

ver ery y

is a ver very y

format form atio ion ns

and

crevi ces

nature

part pa rtic icle less

of go gold ld..

gold will will The rat ath her the th e

are

gol old d,

tive ti ve

Bedrock-controlled cont co ntac actt

with wi th

Var ario ious us

sour so urce ce

age

spite

wat ater er

abil ab ilit ity y of

stag st ages es..

the th e

A smoo smooth th,,

forr plac fo placer er

accu ac cum mula lati tion ons. s.

dec eco ompos osed ed

or po poss sses esss

and

those

of

of bed bed-scouring

a

in their

hard ha rd Bed ed--

crac cr acks ks

clayey

or of a

abilit ity y

to retai ain n

tran tr ansp spor orta tati tion on..

Coarser

crit cr iter eria ia

mos ostt

stre st ream am

dow do wnst stre ream am sour so urce ce

whic ich h

an am amaz azin ing gly

thro th roug ugh hou outt

the th e

stre st ream am

within

sho sh ort

a lon long can ca n

a res resttric ictted

dist di stan ance ce

eros er osio ion n

tran tr ansp spo ort rt,, are ar ea

peri pe riod od..

is dro rop pped

at the the

mouth

of 

cany ca nyon on..

are ar e us used ed in dete determ rmin inin ing g

of st stre ream am

evid ev iden ence ce

depo posi sits ts,,

is struc structu tura rall chan ch ann nel

chan ch anne nell

along

the

stre st rea ams

western

flo fl ow

foot

over

whil ile e

stil st illl

may li lie e

old lde er

tha th an

and an d

(C)) (C

5th An . Rept .

bottom bott omse set, t,

(Aft (A fter er

bed be ds .

Gilb Gi lber ert, t,

at hig igh her

is

Nev evad ada, a,

the th e old ldes estt

syst sy stem em of Tert Tertia iary ry

prove prov ed to be be the rich richest st,, exte ten nsi siv ve

volc lca anic

The hese se

stre st ream ams,

aliz al ized ed

zone zo nes s,

primary whi hic ch

acti tiv vit ity y

the th e

and

them th emse selv lves es

dif iffe fere rent nt

To de dec cip iph her part pa rt search

econom eco nomic

to ta tap p th the e whil ile e

In

tho th ose

cov co ver re re--

the th e re reg gio ion n of 

of the the Sie Sierra rra Nev evad ada, a, man any y stream stream

min ing gle led d.

possib po ssible le

thro th roug ugh h th the e min iner er--

barr ba rren en of gold gold..

of

in his

In

the th e Sie ierr rra a

peri rio ods

are now fou found inte inter -

the th eir his isto tory ry of

and an d re rela lati tiv ve

the th e exp xplo lora rati tio on

for the

conseq con sequen uence. ce.

channels

the th e

oth the er

sub su bje jec cts

of 

age ar are e matt tter ers s

of 

stu st udy

whic ich h

exam ex amina inatio tion. n.

age ag e

geol olo ogic

stre st ream ams,

They Th ey

peri rio ods

of

to the the

the th eir age sh sho ould be rere-

his isto tory ry..

Foss ssil ils, s, per erio iod ds,

epoch chs s of 

dia iag gnost stic ic if

ine in esti tim mable

sis si sti tin ng

Nev eva ada da,,

of lea leaves,

coll co llec ecte ted d

and an d

lish li shed ed

bon bo nes

in

fou fo und in th the e valu lue e

in th this

earl ea rlie iest st

are ar e not, not, how howev ever er,,

geol olo ogis ist' t's s

lake la kes. s.

Cor orre rela lati tion on

of gr gr eatest

land la nd pl plan ants ts

sent se nt

Als lso o,

fro fr om the the old

Inst In stit itu uti tio on

and an d el else se--

faun fa una a ra rath ther er th than an their their

Forr in Fo inst stan ance ce,,

cont nta ain

foss fo ssil il

by pal pale eont nto olo log gis ists ts

fill fi llin ing g

con co n-

the th e wor orld ld ov over er ha have ve be been en es esta tab b-

flor fl ora a or faun fauna. a.

Ter erti tiar ary y

sed se diments

pale pa leo obota tan nis ists ts..

bee een n

on thei theirr mar arin ine e

ass ssig ign ned

pla lant nts s

study stu dy..

peri pe riod ods s

of the the lo lone ne fo form rmat atio ion n nit ite ely

foss fo ssil il

have ha ve be been en ex exte tens nsiv ivel ely y

by

hav ave e

of

to th the e Smit ith hso son nia ian n

larg la rgel ely y

cont co ntin inen enta tall

etc tc..,

dete de term rmin ine ed

som so me ve vert rte ebr brat ate e

Geo eolo logi gic c

par arts ts

log lo gs,

whe here re fo forr scie scienti ntific fic

volc vo lcan anic ic

to a la lava va

regard.. regard

flow fl owed ed..

reg re gio ion n,

tha th at

def efin init ite e

are

stre st ream ams

dep epo osi sits ts

work,

deposi sits ts,,

in whi which ch go gold ld-b -bea eari ring ng

the th e

form fo rm-

whil ile e

physi sio ogr grap aph hic

geolo log gic

dri rift ft min ine es

flow fl owed only over a barr barre en

an ess sse enti tial al

has

of

as wel elll

of

repr re pres esen enti ting ng

by do dogm gmati atic c ru rules les..

geolo log gic

surf su rfac aces es

the th e bu burie ried d ch chan anne nels ls

is

cha ch ann nne els

opportu tun nit ity y

on eit eithe herr

in so som me way tv th the e wel elll-e est sta abli lish shed ed

bedr be droc ock k

an id ide eal

or ben benc che hes s

channel,

and an d relat relativ ive e

of anc ancie ien nt

in th the

had

terr te rra ace ces s

and an d is

bene neat ath h,

ele el eva vati tio ons

the th ere refo fore re,,

to assi assig gn

resu re sult lte ed

whi hich ch cu cutt di dire rect ctly ly

stre st rea am

deepest

geo eolo logi gic c

whic ich h

gold re reso sou urces

mai aine ned d

the th e Si Sier erra ra

forr it was fo fo form rme ed pri rio or to the the

cove co veri ring ng of th the e mine minera rali lize zed d as th the e va vall lley eys s

is often a

In

or wit ith h la lav va,

stre st rea am-b -be ed

mor ore e than than mere super superfic ficial ial

stre st rea am inte in tere res st.

old ol d

Som So me ben bench ches es,,

seq se quen enc ce

det ete ermin ina ati tio on

econ ec onom omic

the th e

and vary ryin ing g

appare ren nt,

reg re gio ion nal

of prim primar ary y

bene neat ath h,

U.S U. S.G.S G.S..

late la ted d

fact fa ctor or

bur urie ied d

may ha have ve be been en le left ft lat later er..

dep epo osi sits ts

depo pos sit

the present

may hav have even been le left ft pri rio or

In ord rde er

age of a pla place cerr

range

(B)

1883..) 1883

The ge geo olo log gic

the

wit ith h detr trit itus us

more anc ncie ien nt

cann ca nnot ot be cla lassi ssifie fied d fore fo rese set, t,

are th the e dee eep pes est; t; yet

cha ch ann nne els

is fi fill lled ed

coverin ing g

dese de serv rve e topset to et,,

of the the mod oder ern n ca cann-

stre st ream am fl flo ows on to top p of th the e de dep pos osit it

det eta ail iled ed

(A)) (A

of

the th e oldes oldestt

hig hi gher

his isto tori ric cal

sho sh owing

i s no nott neces necessa sari rily ly

the th ere refo fore re

It

delta, de

the th e

whic ich h it

the th e newer

benc be nche hes s

a

tha th an th the e ch chan ann nel

yons of th the e Sie ierr rra a - th the e young nge est

flo fl ow

of

For exam exampl ple, e,

In th the e ca case se

norr ye no yett th the e yo youn unge gest. st.

side si de of the the ca cany nyon on..

cro cr oss ss--se sec ctio ion n

the th e most posi positi tive ve

rela re lati tion onsh ship ip..

is you younge gerr

The deep deepes estt

er stre streams,

Idea eall

but

the th e relarela-

cuts.

Wher ere e a can any yon

completel ely y

stre st ream am

0

to acc accum umul ulat ate e

is the the

in

exc ex cel elllent

to resi resist st

app ap par aren entt

fin fi ne

are ar e

good,

mig igra rate te

fro fr om its its

at hig highe herr

whic ich h

sch sc hist sto ose

fact fa ctor or

gold

poor one one

are

Gold Go ld te tend ndss

imp im port rtan antt

deposite ted d

stre st ream am

rock ro ck

it .

olo ol ong

cutti cu tting ng

the

of the the

crossing

or inin-

runn ru nnin ing g

oppo port rtu unit ity y

prov pr ovii de a maxim maximum um

and an d

hold

by up upli lift ftss

a st stre ream am

a grea greate terr

merely

stream stre am s, there therefo fore re,, material.. material

is min minim imiz ized ed

Plo Pl oin inly ly,,

peri pe riod od..

The

the th e Tert rtia iary ry

mar arin ine e bed beds s

sea se a-s -sh hell lls s

to th the Eoc ocen ene e, fossils

val alle ley ys

found of

and an d la land nd an anim imal als s

that th at ha have ve no nott ye yett pe perm rmit itte ted d

or

in the

the th e Sie ierr rra a

mar arin ine, e, bu butt ar are e of an anci cien entt of ge geol olog ogic ic

defi fi--

land la nds s

and an d

age ag e by mea eans ns of th thes ese e brin br ings gs in compl plic icat atio ions ns

the th e tw two o base bases s

of cr crit iter eria ia,,

mar arin ine e

and non onm mar arin ine, e,

Besides, ceou ce ous

most

of

to be pe perf rfec ectl tly y

the

fossil

lea le aves

lake la ke be beds ds th tha at ov ove erl rlie ie

grav gr avel el de depo posit sits, s, evid ide ence

and an d th ther eref efor ore e

as to th the age of th the e latte latter. r.

it rep repre rese sen nts bee een n

because old lde er

in th the e

of the known

gra rav vel

ous usly ly be been en re refe ferr rred ed vill vi lle e

qua uad dra ran ngl gle, e,

as fol follow lows:

Juan Ju an

of than th an

very ve ryli like kely ly

area

of

occur cut

age have

the th e

botanical

Sier Si erra ra Nev evad ada a The Th e tu tuff ffss bedd be dded ed mos ostt

Eoc ocen ene e resu re sult lte ed

lea le afe fed d

specie iess

gen ge ner era a occu oc curr

the th e

found to

a pro rofo fou und

the th e re resu sults lts

fossil

plants

of pal paleo eo--

found

in th the

fosssi fo sill

Gra rave vell s rang range e Dur urin ing g

pla pl ant ntss

occ ccur ur

in age age

from fr om low lower-

thii s tim th time

to te tem mpe pera rate te

inte in terr-

ther th ere e

was

cond co ndit itio ion n

s,

and

of

of pl plants

simi-

the

inc in coming

to tho those se

types

now livin living g

ind in dic ica atin ing g

a

livi li ving ng

in Nor North th

temperate tem

in wes este tern rn

in liv liviing

condit itio ion ns

and an d the young younger er

it pos possi sibl ble e

Mos ostt of the the fo foss ssil il

cli lim mate,

Eocene

to di diff ffer ere ent ntia iate te

vert ve rteb ebra rate te

bone nes s

form fo rmat atio ion ns

have

bet etw wee een n

loc lo cati tio on,

as

who

is not always that

pale pa leob obot otan anist ist;;

whic ich h

weste terrn

geolo log gic

gene ge nera rally lly

work rks s

apt to ap apply

has

been

wit ith h

assigned

in the the

Mount nta ain

have

been

who

wer ere e emvert rte ebra rate te

the th em by th the a yo youn unge gerr as

ressul re ulti ting ng

cou ount ntie ies, s, lattit la ite e

regi re gion on..

resu re surr rre ecte ted d [19 [1 934 34]] bee een n

resurre rec cti tio on

cut

into

pre re..-C -Cre reta tace ceou ouss

af

the

fra rag gments

has

of

whe here re

serv rve ed earli ear lie er

of

gra rav vel s of

volc lca anic

bed-ro roc ck

been

stages

bear be arin ing g

gra gr ave vels ls

wer ere e

the th e

latt la tter er

amou am ount nt

and an d Re Rece cent nt

bedr be droc ock k

unm nman antl tle ed epoc ep ochs hs

Tertiary aft fte er

volc vo lcan anic ic

land

havin ing g

found the

chan ch anne nels ls

hav ave e

that th at

Table

in

g ol oldran ra n in

Mounta taiin

nev ne ver

cont co ntai aine ned d

any an y appr appree-

cont co ntra rary ry

to the the com com-

surf su rfac aces es

which

buri rie ed

thro th roug ugh h

of upla upland nd have

are act ctu u all all y

been

thro rou ughout

P le leii s-

pene pe nepl plai aine ned d brought

late la terr

to

Terti tia ary

epoc ep ochs hs

The nat atur ure e the

be

area,

and an d di ss sse ect cted ed

Lithol Li thologi ogic c

ancie ien nt

what

These to

grav gr avel el,,

frag fr agm men ents ts

forms, been

beds,

age.

may

to the the

and in pIace pIace s gra grave vell-co cove vere red d

early lig igh ht

angle

bodie iess

appe ap pear arss

this th

in anc ncie ient nt

app ppar aren entl tly y

Ter erti tiar ary y not only

lake

Tert rtiiary

In

is

al so the under-

of whi hich ch

of go gold ld-b -bea eari ring ng

mon bel bel ie ief. f. Th Thou ough gh toce to cene ne

min ined ed

but

structure,

or at an

late la te

mud-f -flo low ws,

earl rliier

bedrock

of 

and an d Cal alav aver eras as

geolo log gic

ages,

resurrection.

opposite

Cha hann nne el; ciab ci able le

by of

the

feat fe atur ures es

ressis re ista tant nt

mate terria ials ls,, di ff ffe ere ren nt of

rec re ceiv ive ed

of pre preserv rviing

ressis re isttant

the th e top topog ogra raph phy y

controlled

various

less

surf rfa aces

surf su rfac ace es,

Tuo uolu lum mne

purp rpo ose

and

is a widespre rea ad not

invo in volv lve es

a ve very ry

the th e

alon al ong g

loca lo call ity ity fo forr th thii s stu tudy dy

Mou ount ntai ain, n,

and

stre rea am

proce pro cess ss

Tert rtia iarry

bedr be droc ock k

Nevada,

One ke key y

of Ter er..

of ear early

here reto toffore

The

consis isti tin ng lyiing ly

Sierr rra a

whic ich h

of Ta Tabl ble e

has

unco un cov ver erin ing g

the th e

Cal alif ifor orni nia a,

flo fl ow

in the the

and

it de dese serv rves es..

regi re gion on

channels

of the the mat ater eria iall

and vall lle eys

peri rio od

grav gr avel els, s,

chan ch anne nell

Criteri Cri teria a

and an d compos osit itio ion n

geolo log gic

peb pe bbl bles es,,

Sie ierr rran an Ter erti tiar ary y

corr co rrel elaa-

lea le af lo loc cali lity ty

has on only ly re rece cent ntly ly

eco ec ono nom mi c conc concer ern. n.

been col-

the th e same age to

the th e form former assi assign gns s

age. Many of th the wel elll-es esta tabl blis ish hed

fla fl ank

process

reco re cogn gnit itio ion n

a deposi sitt

com co mpo pose sed d

or of of th the e bed edro rock ck compl plex ex,, is of th the e prepre-vo volc lcan anic ic

duri rin ng th the e la latt tte er compose sed d

of andesi site tes, s,

late la te Mio ioc cene basa ba salt lt of la lati tite te,,

and flow flo ws.

early

of

form fo rmed

and in the the Oli lig go-

the th e volc lca anic

roc ro cks

see se em to be be la larg rge ely age.

Ple leis isttocene Tab able le

Eoc ocen ene e

were appa pare rent ntly ly

Pli lio ocene

Tuo uolu lum mne

to

Gold ld-that th at th the e

perio pe riod d po poss ssib ibly ly

whic ich h

or earl rly y

indicate

belo lon ng.

indi in dic cat ate e

part of th this is peri rio od

The most abundant

Pli lio ocene

als lso o may

fill fi llin ing g

pure pu rely ly of sa sand nd an and d quar quartz tz--

in age. age. Most of th the e rh rhyo yoli lite tes s cene.

pale leo onto tolo log gis istt

ash

f arm rme erly

bear be arin ing g

so th tha at th the e ex-

in whi whic ch th the e fo foss ssil ils s

surf su rfac ace e

Tabl ble e

surf su rfa aces

tim ti mes of 

fou fo und in th the e YoYo-

of a fo foss ssil il

Tuolu lum mne

eros er osio ion n

volc lca anic

from fr om

bedded bed ded are unk unknow nown.

beds

Qua uate tern rna ary

they th ey

Grav Gr avel els. s.

by per erso sons ns

ass ssig ign ns

and an d Quate tern rnar ary y

fea fe atu ture res s

old

don do ne pure rely ly

Matt tth hes

old su surf rfa aces

dur urin ing g th the e Pl Ple eis isto toce cen ne

and the the

desc de scri ribe bed

of th the e Sie ierr rra a Nevada

did not not re rec cord th the eir defi fin nit ite e

The

includes

alth al thou ough gh

of the Aur urif ifer erou ouss

and an d se sen nt in to pale leon onto tolo logi gist sts s

remain ins s

tha th at

Asi a. The ev evii de denc nces es

in th the

rea re adi dily ly flor fl oras as

Amer eric ica. a.

Amer eric ica, a,

Amer erii ca an and d ea east ste ern

mak ake e

The

The

dir ire ectio ion ns

larg la rgee-

the th e dri rift ft min ine es

in th the e

anci an cien entt

the th e tw two. o.

Mio ioce cene ne..

Mio ioce cene ne

actt geol ac olo ogi gic c

beds be ds do

are

sho sh owin ing g

in whi hic ch

the th e ol olde derr

lect le cte ed

old lde er

Nevada

the th e vicinit ity y

.a

and an d oth othe er

no long longer er

of diff diffe ere ren nce

peri pe rio od;

ind in dic ica ati tin ng

F.E .E..

tyin ty ing g in the Mio ioce cene

occ ccur urri ring ng fac fa ct

bee be en

given gi ven con conside sideration ration.

San Sa n

of pa palm lmss

in east easter ern n

regi re gion on,,

wer ere e

of Ple Pleist istoc ocen ene. e.

som so met etim imes

Plio Pl ioc cen ene, e,

sem se mit ite e

the

fou fo und in th the ese

Mio ioce cen ne,

to the the vari rio ous

it is is so

to an an ear arli lier er

the th e Sie ierr rra a

from fr om su subt btro ropi pi ca call

flo fl ora

Eoc oce ene ne,,

bon bo nes

Crite Cr iteria ria

evid ide ence.

upli lift fts s

surfa fac ces,

of Nor North th

desig de signa natio tion n

has

physi sio ogra rap phic

3 mil ile es

in the the elim elimin inat atio ion n

in ge gene nera ral, l,

Mio ioc cene

chan ch anne nell

mar arin ine e Cre reta tace ceou ous s

the

Aur urif ifer erou ouss to uppe upperr

on

by

as fo follo llow ws:

a cI im imat atii c trend trend whi hic ch lar, la r,

been

of

and an d sh shal ales es

in the the

Age corr rrel elat atio ion n

vasst va

sed se diments ts,,

of

gra rav vel

is not notew ewor orth thy; y;

has ha s su sum mmar ariz ized ed

study

con co nta tain inin ing g

tha th at no fo foss ssil ils s

in age age be betw twee een n

R. W. Cha hane ney y

In the the Smar arts ts--

age. ag e.

foo fo ot of

channels

Meso soz zoic

diffe di ffere renc nce e

wood has pre rev vi-

vert ve rteb ebra rate te

Phys Ph ysio iogra graph phic ic

tio ti on wit ith h geolo log gic

The

age is de desc scri ribe bed

to belo belong ng

yet

on th the e west ste ern str tre eam

period.

a dep epo osi sitt

Hil illl

be ass assum ume ed

Whe here reve verr de defin finite ite

oldest

tha th at

foss fo ssil il

grav gr ave el

It is a fact, fact, however, grav gr avel els. s.

of

welll-w washed

Mon onte tezu zum ma

it is of of Cre reta tac ceo eous us

Cre reta tac ceous

In mos ostt

by pa pale leob obot otan anis ists ts

Eoce cene ne

the th e ad adja jace cent nt

that th at it mus mustt

grav gr av--

con co nta taIn Inin ing g

once on ce gi give ven n th the e bl blan anke kett

tia iary ry

isolate ted d

nort no rthh-n nor orth thw west muc uch h hi high gher er

Eoc ocen ene

forr exa fo xam mpl ple, e,

Lind Li ndgre gren n

wood, so

form fo rms whic ich h

to the the Cre reta tace ceou ous.

logs lo gs of pr pro oba bab ble

hig igh h,

tro tr opic ica al

this th is

petr pe trif ifie ied d

The

Foss ssil il

bed be ds

qua uart rtzz-

nor diag diagno nost stic ic..

cli lim mate

conta tain inin ing g

in tu tuffa-

of th the e go gold ld-b -bea earin ring g

unst stu udie ied d

plac pl aced ed

wel elll as later later

do no nott gi give ve muc uch h di dire rect ct

els el s is no nott as yet yet de dete term rmin inab able le hav ave e

occur

the th e go gold ld-b -bea eari ring ng

com co mmon in the most most an anci cien entt case ses s

coo co ord rdin inat ated ed..

Duri rin ng

the th ere

Mou ount ntai ain n

prob pr obab ably ly of late late Pli lio oce cene ne

age. ag e.

are of 

the th e la late te

were ma many is co com mpo pose sed d

In the pell pe lle ed

Recent

epoch

fro fr om cra crate ters rs

much

thou th oug gh

has

been

from fr om whi which ch

mudf dflo low ws

quot qu oted ed fr from om an au auth thor orita itativ tive e

ex-

par arts ts

of 

be co con nsi side dere red d

thei th eirr

grav gr avel el

may rece receiv ive e

young nge er

hass ha

tha th an

been be en de deri rive ved, d,

the th eir

mate teri ria als

fro fr om

act ctiv ive e volc lcan ano oes es.. Ther Th ere e is her ere e an opp opport rtu unit ity y forr a fo pet etro rog gra raph phic ic stU st Udy of bo both th volc volca ani nic c rock ro ckss an and d th the e mate ma teri rial alss

of the the sedi sedime ment nts. s.

of stre stream am

corr co rrel elat atio ion n

the th e

meth me thod od

prev pr evio ious usly ly

Spec Sp ecia iall

deta de tail iled ed

as

ment me ntio ione ned d

"he heav avy y

mine mi nera rall

anal an alys ysis is

down (3)

volu vo lume me of it itss The mile le..

AND AN D HABI HABIT T

Need Ne ed fo forr Scient Scientifi ific c

Expl Ex plor orat atio ion n chan ch anne nels ls

of pl plac acer erss

req re qui uire ress

life li fe hi hist stor ory y

of

sepa se para rati tion on," ,"

die ient ntss

the th e fi firs rst, t,

esssen es enti tial al men enta tall

scie sc ienc nce e

sim si mple

yet

maste ma sterp rpie iece ce

exp xplo lora rati tio on

geo ge olo log gis ist. t.

proc pr oces esse sess

are so univ ive ersal

that

oth ther er..

Sim imil ilar arly ly,,

Tert Te rtia iary ry

stre st ream amss where

fund fu nda a-

in 1877 in a Gil ilb bert

of th the e Sie ierr rra a

of

of pro proce cess sses es and

As a rul rule,

the th ese

extr ex trem eme. e. rise

by ap· ap·

24 fee feett

and an d the

such su ch

floo fl oods ds

stea st eam m

envir iro onments

suc uch h

development

of

as

the th e

inte terr rru upted

the th e Sie ierr rra a drain ina age

by

earth

buri bu rial al

as a resu result lt

of volc volca anic

flo fl ows,

the th e hi hist stor ory y

of the the

horizon

enti en tire rely ly ear arli lie er

is

diff di ffer ere ent or

the

a

stre st rea am

in

entity,

form fo rm and and

sub su bse seq quent

This Th is

of any anyone

or by by chro ron nomay be be

fro fr om eith eithe er fac fa ct,

system

tog to geth ther er

presents

a

problem prob lem much involved. involved. The Th e ne need ed fo forr a scien scienti tifi fic c of stre stream amss feat fe atur ures es

is th ther eref efor ore e

of th this is

are ar e ou outli tline ned d

stud st udy, y,

toge to geth ther er

divi di vide ded d

wit ith h

fluv vial or flu

in the study study

with wi th its te term rmin inol olog ogy, y,

into in to th the e se seve vera rall

abrasio abr asion. n. solu solution tion.. men entt of the the essen essenti tial al

Erosion Ero sion

erosion

is

proc pr oces esse ses, s,

comple lex x.

fact fa ctor orss

It may be

hydrau hyd raulic lic acti action. on.

and trans transpor portati tation. on.

A brief brief sta state te--

whic wh ich h co cont ntro roll

ones

by

are ar e wor orn n dow down

the th e

stream

of wat water er,,

gre reat at

eno en ough

to

and to r is ise

in

flu fl uct ctu uat atiions

Mis issi siss ssip ippi pi

are hass ha

The The

channel

velo ve loci city ty..

lesss les

a no norm rmal al

Nile

normally

ero er osi siv ve

efffec ef ectt

of 

seen

in cr cross-

fric fr icti tio onb nbet etw wee een n

dow do wn, ve velo loci city ty

area ar ea

channel

is gre great ates estt

in pro propo port rtio ion n

s' th ther eref efor ore e

shal sh allo low w

to vol volum ume e give gi ve

grea gr eate terr

ones on es..

to acq acqui uire re amount

as

Sin Si nce

a stre stream am

bro br oad ad,,

poss ssiible

are ar e

and an d cha ch ang-

to be be read readil ily y

seasons,

32 fe feet et..

smal sm alle lest st

con co nti tinu nues es

Vel elac acit ity y alw al ways

belo be low. w.

narrow

than th an

in all all st stre ream ams, s,

slig sl igh ht

20 feet.

Gan ang ges

gre reat ates estt

a load load unt ntil il per erm mitt tted ed

and an d ki kind nd of mate materi rial al

eros er osio ion n

is

of ero erosi sive ve

and an d ab abra rasi sive ve

frag fr agm ments

of

it is carr carryi ying ng

by

the the

grad adiien entt,

avai av aila labl ble. e.

If th the

vel elo oci city ty

rock ro ck fragm fragmen ents ts

the ma maxi ximu mum m a

velocity lea easst

of

a

In oth other er

squa sq uare re

and an d th the e si sixt xth h law la ws

acc ac complis ish hed

cond co ndit itio ion ns, such

42-44.

I, Ph Physi sica call

gra rav vit ity y,

the

the

shown

rock ro ck fragfrag-

doubling

abrasive

con co nditi tio ons pow po wer

of  the

squ sq uar are e

that

of 

In oth other er

indi in divi vidu dual al

as its

diam amet eter erss

4 ti tim mes es..

the

power

at

as much much as 64

vari va ries es

betw be twee een n

the th e

pow po wer  of  the velo velocity city..

butt bu

exp ex pla lain in

the th e

str trea eam ms

tha th an

they th ey

incr in crea easi sin ng

tre rem mendous

*Lo *L ong ngw wel ell, l, Par artt

abra ab rasi sive ve

by swif swiftt

grea gr eatl tly y

of  th the e

cerrtai ce ain n

If all all th the e

woul wo uld d ta take ke pl plac ace. e.

vari va ries es

increases

under

nott only no only

nor orm mal

both bo th tran transs-

spe sp eci cifi fic c

incr in crea ease sed d

have

wor ords ds,,

floo fl oods ds;; have

mov ove e

stream

tim ti mes es..

The hese se

diame dia meter  ter 

can

and an d

sam sa me

be dou double led d,

move mo ve ar are e

Calculations

4 tim times es,,

the th e

of a stre stream am

words.

...

had

it ca can n

stre st ream am

conc co ncer ern n

defi de fini ni te actio action n

ments velo ve loci city ty

pow po wer er" "

powe po werr of the the st stre ream am..

roc ro cks

then th en th the e fo follo llowi wing ng

The Th e mo more re pert pertin inen entt

here he re.. Streom Stre om

Stre St ream am

back ba ckgr grou ound nd

appa ap pare rent nt..

too

they

lowe lo werr

15 to to

the

Deep,

port po rtat atio ion n

and la lav va

and

patt pa tter ern n

syst sy stem emss.

complexity

movements of an any yone

separate

where

has been

mud wash washe es

low lo wla land nd

would

Nevad ada a,

system

of

A st stre ream am the

in-

high gra-

low

fact fa ctor or

reg re gio ion ns,

the th e

slo sl ows

The Th e "la laws ws

In a pro provi vin nce ce,,

logical

of

velo ve loci city ty

the th e

wit ith h

It fo foll llo ows

to

rain ra infa falll.

are ar e

reg re gio ion ns

infl in flue uenc nces es

and an d chann channel el

water.

alo al ong

than th an

are ther eref efo ore

chan ch ang ges

is con consi side dere red d

in ch chan anne nels ls of

per

wit ith h

gra rad die ient ntss

in

str trea eam m

spri sp rin ng

rise ri sess

also al so

feet

rap ra pid idly ly

down

as the the

In other

level

volu vo lume me

foun fo und d in ope opera ratio tion n

othe oth ers rs..

shape

to pla place ce

low lo w grad gradie ient nts. s.

is a vari variab able le

in so some

Ever Ev ery y

The

wit ith h

to d ry ry u p at at certain

in water

appea ap pearr sim similar ilar..

rep re peate ted dly

but

streams

many

more mo re quic quickl kly y

fluct fl ctu uat atiions

ing.

the th e anc ancie ien nt

may be gai aine ned d

of

in any any

wat ater er

foun fo und d in anan-

of wat water er

of ero erosio ion n

at

of   and

must mu st de decr crea ease se..

rat ate e

flo loo ods

volume weight

is th the e stream

so

str trea eam ms

gradients

and an d that that

bec ecau ausse

sect se ctio ion n

to st stre ream amss

high

eros er osio ion, n, volu vo lum me

cause

vol-

on (1) th the

(4)

inc in cre reas ase es

muc uch h

size si ze

wear

as

mounta tain in

val alle ley ys

of com compa para rabl ble e

The Th e

on its

(2)

and

fro rom m pla lac ce

Velo loc cit ity y Thus

thei th eirr

streams

lar arg gel ely y

in his

of th the em in one par part of 

to con condi diti tio ons

conditi tio ons

is imim-

Utah Ut ah..

und nde ers rsta tan ndi din ng

the th e kn know owle ledg dge e

tod to day

by G.K .K..

a study

an

The Th e

as those those re rela late ted d

the th e worl rld d may be app ppli lie ed

wit ith h

ero er ode

notice cea able le,,

of whic ich h is

was ou outl tlin ined ed

mann nne er

on

whil wh ile e th the e se seco cond nd ha hass

on th the e Hen enry ry Moun Mounta tain ins, s,

Such Su ch natu natura rall

Eac ach h

kno kn owle led dge

sple sp len ndid

and an d

and an d depos deposit itio ion, n,

fea fe atu ture ress,

of st stre rea ams

stre st ream am

incl in clud udes es,,

his isto tory ry..

more mo re dire direct ctly ly,,

to the the

This Th is

of eros erosio ion n

physi sio ogra rap phic

to do wit with h re reg gio ion nal

anci an cien entt

of th the e hab habit itss

in gene genera rall.

proc pr oces esse sess

and on the the ot oth her er,, port po rtan ant; t;

and an d va vari riou ouss

flowing,

expressed

chan ch ang ges

str trea eam m.

the th e ra rate te of eros erosio ion n

Backg Ba ckgro roun und d

channel,

of the the bed of a str strea eam m

grad adiien ent. t.

cont co ntin inu ued

is

its

ordinarily

grad adiien entt

cre reas ase e

OF ST STRE REAM AMS S

an un unde ders rsta tand ndin ing g

of stre stream amss

the th e on one e ha hand nd,,

the

The

stream of

depen end ds

in tu turn depen end ds

load lo ad..

It i s

stre st ream amss

the

shape

as follo follows ws::

to ero erode.

vel elo oci city ty

of des desc cen entt

by mea means ns of 

as wi wide dely ly em empl ploy oyed ed in pe petro trole leum um

HIS ISTO TORY RY

ratte ra

gradient .

The

which the

of th the

geology.

plyi pl ying ng

slope

text te xtbo book ok··

of a stre stream am

vel elo oci citty.

water,

that LIF IFE E

cap apac acit ity y

cou co urs rse e

migh mi ghtt be per perfo form rmed ed

know kn own n

The ume an and d

the Sierra Sierra Ne Nevad vada. a. Str trea eam ms may alw always the th e ro rock ckss

pumice

and an d blo low wn over vari rio ous

Kno nop pf,

sho sh ow

and an d

Flin Fl int, t,

Geo eollogy:

John

by

gre reat ater er

by slo slow

clea cl earl rly y

velo ve loci city ty des esttru ruct ctiv ive e

vast va stly ly

under

why exce except ptio ion nal

increa incr easi sin ng

power. A Te Text xtbo book ok Wile ley y

eros er osio ion n

ones

The of

& So Son ns,

vol olum ume, e, volu lum me

of 

Geo eolo logy gy.. 1932 19 32,,

pp.

the th e

Colo lora rado do

Riv iver er

mea easu sure red d

flood

in

1921,

was

when

the th e

St.

Francis

1928

and

flooded

cret cr ete e

wei eig ghi hin ng

esca es cap pin ing g which 13

wat ater er..

grav gr avel el

of

depo de posi sitt

pare pa red d

the

Ayain,

gave

way in

blocks

wer ere e

of

move ved d

con-

by th the

the th e

Goh ohn na

floo fl ood d

the

water

picked

up and

that th at

thro th rou ugh

the th e fi firs rstt

stream

made

of

The

foll fo llow owin ing g

des escr crib ibe ed,

of bou bould lder erss

into in to

the th e

are ar e

proc oce ess sse es.

weathering

from fr om the the ou outc tcro rop p larg la rge ely

stre st rea ams

Gilbert

193 19 32, p. 4) m,. m ,.aximum aximum diameters at cert certai ain n

Velocity

(inches)

pre re-are ar e

disi di sint nteg egra rati tion on,,

hydr hy drat atio ion, n,

F.e.. F.e

from fr om

Diameter

are

Part rtic icle less

by surfa surface ce

of oxida oxidati tion on,,

firrst fi

quot ote ed

velocities:

1895 95,,

whic ich h

is

whi hich ch ca can n be mov moved ed in slui sluice cess

and an d so solu lu--

(fee (f eett

perr sec pe secon ond) d)

2

3.3

4

5.3

6

6.2

8

7.4

10

8.4

12

9.1

a co continuous

the th e mat mater eria ials ls

tab ta ble

J oumal,

(Engineering

from fr om 50 50 to 234 234 fe feet et th thic ick. k.

thro th roug ugh h

cons co nsist istin ing g

huge

of gra rave vell

course

duri du ring ng a

volume.

Angeles

each ea ch,,

hours,

and an d was ashe hed d

loos lo osen ened ed

Los

ton to ns

Ari rizo zon na,

normal

belo low w,

quan anti ti~i ~ies es

As pr prev eviious usly ly rem emov oved ed

near

duri rin ng

four

its

its

val allley

In In India ia,, just

such su ch

mi les

dam

the

at Yu Yuma,

times

up to 10,0 ,00 00

lasted

tran tr ansp spor orte ted d

155

16

10.8

20

11..9 11

24

13.0

30

13.7

tion. Sinc Si nce e past

clim cl imat atic ic

than

mat ates es

they

envi en viro ronm nmen ents ts are

now,

is an imp import rtan antt

deve de velo lop pmen entt impo im port rtan antt

imbedded and

give gi ve

subject

prob pr oble lem m in the

rel elat atiion

chan ch ann nel els. s.

d"ep epos osit itss of an anci cien entt

com omp pos osit itio ion n

of

the th e

cli-

to th the e

The stud study y

give gi vess

Tran Tr ansp spor orta tati tion on

in the the

of anc ancient

in its its

strrea st eam m

clue cl ue to the the natu nature re

cond co ndit itio ion n selv se lves es

the

of an anci cien entt

of fos fossils

were we re di diff ffer eren entt

the th e most most

clim cl imat ates es..

The

sed se dim imen ents ts

In solution,

susp su spen en sion, sion,

sub su bj ect of riv iver er dat ate e

the th e ca carr rryi ying ng

much def efin init ite e powe po werr

ment me nt is qu quot oted ed 01 ca can nal

info in form rmat atio ion n

of stre stream ams. s.

from fr om Davi David d

bro rou ugh ghtt

The Th e

as

Stev St even enso son: n:

"bed

rega re gard rdss

carr ca rrie ied d

stat st atee-

(Prin (P rinci cipl ples es

...

samp sa mple led d

load"

channel plac pl ace e

on

the the

size

wit ith h di diff ffer eren entt

of

detr triital

parti tic cles

velo ve loci citi ties es

are ar e sa said id

from fr om ex expe peri rim men ents ts

which

strreams st

to be be cap capab able le

.... ..

flowing

of ca carr rryi ying ng::

mOe per hour,

work wo rk on fine fine 6 in. pe perr se sec.c.-0. 0.3 3.40

will

just

begin

to

clay cl ay..

mile

per

hour,

will

lift

fine

sand. coar co arse se 10 in in.. per sec. sec.-0 -0.5 .5

will

lif iftt san sand

as

as li lins nsee eed. d.

mil ile e

perr hour, pe

wil illl

lift li ft grav gravel el

the th e

si ze ze of pe peas as.. 12 in. pe per se sec.-0.6819

the

alo al ong

gra rav vel

24 in. in. pe perr so soc. c.-1 -1,,3638

mi (e (ess

will

sweep

'le 'l eap apin ing g'

bed

the

the

posi po siti ting ng

in

into

pro rog gre ress ssiv ive e loa lo ad,

of hi hill llss thei th eirr ated at ed

chan ch ang ge

the

dunes

becomes

succ su ccee eede ded d

eroding

trav tr avel elss face fa ce..

bed lo load ad is smal small, l,

dunes es,,

whic ich h

is li lik ke

that th at

tend te ndin ing g

Wit ith h

to in incr crea ease se

and an d

the

phase

rhy rh yth thm mic

phas ase, e,

in whic ich h

of

and an d dede-

f ac aces es..

smooth

The hese se

trav ave el

of eo eoli lian an

fac ace es

The

rhyt rh yth hms

of wate waterr

susp su spen en--

tran tr ansp spor orta tati tio on,

di sap app pear

is acco accom mpl plis ish hed Both

bed loa load

as fol follo low ws: the th e

of cond condit itio ion ns

upst up stre ream am..

by rhyt rhythm hmss

of

upstr tre eam

eve ev entually

by a sec secon ond d

mov ovem emen entt

of the

calle led d adva ad van nce thei eirr

smooth.

takes

the th e parti particl cle e

mat ater erii 01 on the the do down wnst stre ream am

erod er oded ed

the

hills

which

to hy hydr drau aulic lic

such su ch th that at

of

load i s a sm smoo ooth th

of ju jum mps ps..

is expr expres esse sed d

mode

easi silly butt th bu the e

The alon al ong g

and an d ca caus uses es

"Mod odes es

are ar e

wate wa ter, r,

are

by saltation,

of

The heir ir

any an y

on

accessible.

contrast

molded currren cu entt

the th e

who ca carr rrie ied d

mea easu sure red; d;

transportation

move mo vem men ent" t" is

by

suspension

or rol rolli ling ng

as

sum su mmary

dow do wns nstr trea eam m.

alo lon ng

with wi th ru runn nnin ing g

qua uant ntit ity y

in a serie seriess

calls

from

is

deb ebrri s in

are ar e call called ed

anti an tid dun unes es;;

by ero erosi sion on

on the the

deb ebri ri s mov movem emen entt

turn tu

a syst system em and an d down-

are ar e

init in itii-

move mo veme ment nt..

si ze of be bean an s. wi II ro roll

alo al ong

wi II swee sweep p

stones

the

siz ize e

In sho show win ing g be,, Gi be Gilb lber ertt

1 in inch ch ..in in di amoter. amoter.

per hour ur,,

angular

egg. eg g.

hour,

per hour,

pebb pe bble less

sliippery sl hen' he n's

the th e

mi les

roun ro unde ded d 3 ft. ft. per per se sec. c.-2 -2.0 .045 45

per

in

less

well

When the the co cond ndit itio ion ns

stre st ream am

mile

borne

much

tract tra ctio ion n

surface

8 in. pe per se sec. c.--0.4545milep epe erhour,

expe ex peri rim men ents ts

by slid slidin ing g as

His

dunes, 3 in in. per sec. c.--0.170

is

bed,

coll co llec ecti tive ve dedu de duct cted ed

are ar e depos deposit ited ed

sedim entatio entation n

aft fter er

when wh en th the e be bed d is un unev even en

sion. are ar e resul results ts

soluti sol ution, on,

and an d th thei eirr

forw fo rwar ard d

hydr hy drau aulic lic

foll fo llow owin ing g

carr ca rrie ied d

of 

'salt 'sa ltat atio ion. n.''

material s

Gilbert

The Th e

call ca lled ed

to mov move e ir irre regu gula larl rly y

p. 361).

and an d ri riv ver eng engineer ineering. ing.

the

for orth th at

foll fo llow owin ing g

from fro m

labo la bora rato tory ry

enou en ough gh

engi en gin nee eerrin ing g

thus th us

It has be been en sh sho own by G.K G.K. Gil ilb ber ert, t, exte ex tens nsiv ive e

anot an othe her. r.

mat ater eria ials ls

of ma mate teri rial alss

and by the the pr proc oces esss

suspension.

and an d gr,ounding

that th at proc proces esss

the th em-

Transportation

an ea earl rly y

The

precipitation

that

The

through

saltation.

by

is do done ne by the the carryi carrying ng

alo al ong of a

The

flow

how ho w compl complic icat ated ed

acti ac tion on

may ma y

state sta tes: s: of 

0

inte in tera ract ctio ions ns

whi hich ch

si s.

tra tr actio ion n

Stre rea am

a stre stream am's 's

stre st ream am have ha ve

is a com compl plex ex thus th us

is not

forr baf fo baffl fled ed only

pro roce cess ss..

invo in volv lvin ing g

mec echa hani nica call

a fu fun ncti tio on

of

strream st

anal an alyyflo fl ow

but

itsel elff

adds

com co mple lex xit ity y of th the e

which

carries

fac acttor;

the

smal sm alll

chan ch ange gess

affected

each

facto torr;

place

If th there the

div iver ersi sity ty

gre reat ater er

tran anssported deb ebrris

deb ebri riss

is a fact factor or,, shapes

this th is

inff lu in luen ence ce found

turns

of

width.

is not

wel elll and

of th the e wat ater er,,

als lso o

the

with

The

of

impuri ritties es,,

bein be ing g

fav fa vor orab able le.. natu turre

of

banks

the th e

banks.

vary va ryin ing g

wheth the er

of 

facto fac torr

affec ectted

and an d

a pro prope pert rty y

of 

is

to

a fa factor

So, too too,

is

with wi th te tem mpe pera ra--

dissolved

or su sus-

pended.. pended

Gil ilb bert

cla lass ssif ifie ies s

transpo tran sportat rtation ional al The purp pu rpo ose   ject ject

of str streams

than th an

a ter term min ino olo log gy

other

to aff affor ord d

her ere e

given

has

con co nven enie ien nt

the th e tha th an

supplied

stre st ream am

erod er odes es

tem emp porar ary y

of

the

corr co rrad ades es

it.. it

Whe hen n

the

cap apa aci citty

curr cu rren ent, t, Some

of the the

but th the e str tre eam amss

stre st ream am

rock ro ck,,

whi hich ch

their the ir

develo dev elopm pment ent..

their th

no other

to the the su sub b-

one

or both both

vium,

and

ero er odi din ng will

bank ba nkss

thei th eirr

local

of

dep de pos osit it

file fi less

and

the

cap apa aci citty,

Thro rou ugh to thei theirr to

thes ese e

and a

one

An all allu uvi vial al plaiin pla

when

stre st ream am

that

calle led d

tim ti me of fl floo ood d.

is

outl tlin ined ed

terrms te

than corr co rrad adin ing g in

a fl flo ood

case

pla laiin,

cause

other

fine fi ne al allu luv vium um..

is

of deb debri ris s

In a str strai aig ght dle

than

than th an

sup su ppl ply y

debris,

builds

reduces

erosi sio on

adjust

The pr pro oce cess ss it

is less less

their

re-re pro ro--

of ad adju just stm men entt up i ts ts is

bed

the

it over

an ag agg gra radi din ng is

bordered

which

the

by wat ate er

said

to de de-

stre st ream am

also al so;;

an a ll lluvial spre rea ads

the

curv rve es

stream.

by wh whic ich h

for

small

is one of of the

may

is em embo bod die ied d

the th e

of an an allu alluv via iall

go wi with

con co ndit itio ions ns

pla lain in,,

finer

the

streams and an d bebe-

all llu uvium,

stre rea ams

are

it is

asssociate as ted d

the

wat ater er

scend sce ndss

obli ob liqu quely ely..

oute terr

sult su lt

is

tow to war ard d

the th e

ten te ndi din ng ner. ne r.

tow to war ard d

Anot oth her

med edii ai ai,,

two

velocities

grea gr eate terr

than th an

any

a

They Th ey

ben end d

hav ha ve is

are ar e

the

cross

section

the

dep eptth

win indi din ng

stre st ream am

chan ch ang ges

fro rom m one one

side

fil ila aments

is rev eve ers rse ed,

to the

only

The much

are ar e

gre reat ater er

part

of th the

forr tra fo tract ctio ion n,

they

erode

han and d,

until

the th e

approac ach h they th ey

the

ban ba nk.

not

stra raiight

an

curr rre ents the

dep de pos osiit

the

inner

what

dir irec ecti tio on twis istting

they

a ph phas ase e

and an d this this at

right

in pos positio ion n,

of

system wit ith h

phas ph ase e

shoal angles

ban ank  k .

itss it

of

of

to

As

curv cu rvat atur ure e currren cu entt

depth th,,

but

more equa equab ble

pro rod duc uces es

does

ten te nding

is a sy sym-

oute terr

sysste sy tem m

it th the

The

a c ur urve

the

incl in clu ude dess

deep de epss.

in a d ir irection obli liq que

the th e

on

near

and with

of vel velo oci citi ties es,, two tw o

being

other,

of chan change ge the th e

som so mewhat

across

cap ca pac acit ity y

other

in-in

Conn nnec ecte ted d

but they they

obliquel ely y,

the th e

carr ca rry. y. that

sep se par arat atin ing g

are

lea le ad

and an d

gre rea ates estt

dist di stri rib but utio ion n

ban ank k. the th e oute outerr

ban ba nk

re-re

curr cu rren entt

is no no lon longer

velocities

curr cu rren ents ts,,

the

pro roce cess ss

gen ge ner eral al

tow to war ard d

in a re relati tiv vel ely y

On the the

ban k  

low lo wer

bank

tract ctiional

the th e

that

of the the

curr cu rren entt

gre reat ater er

in turn

par arts ts

nea earr

inne in nerr

bed

slac sl acke ken nin ing g

of

outer

ther th eref efor ore e

atttain at ine ed.

One

de-

tow to war ard d

neQr

or conc concav ave e bei ein ng

the th e

the

crossing

can ca n no longe longerr

the th e

the

near ne ar

by inc incre rea asin ing g

equ eq uilibrium

oute ou terr gradation gr

near tho th ose

the th e

slow-

wat ater er

displace cess

laye la yer. r.

swif sw ifte test st

The itse sellf 

the

is cro crowded

uppe perr

forr fo

pro rojject ctss

and an d th that at

water

and an d

the th e

velo ve loci citi ties es

bed velo veloc citi tie es

stre st ream am.. and an d

the th e

is

the th e gre reat ater er

the th e

ban ank k

is th that

is ne near ar

these

bott bo ttom om,,

oute ou terr

slower.

the

and an d

as an upp upper er

resi sissts

for

previ ou ou s Iy

mov ovem emen ent, t, the th e

strea eam m

it di disp spllac ace es

whic ich h

the th e mid id-mid-depth

effec ecttiv ive e

ban ank k,

desce cen nding

mid idd dle

whole

lea easst

water

near ne ar

above

is mo more

than

the th e

wat ater er,,

the

resu re sult lt

butt bu

stream

In so so doi doing

The

is a twis twisti tin ng

the th e

res esiista tan nce

Iy ne near ar

low lo wer

wh i I e

swifter

deflect def cte ed

bank.

slow sl ow-f -flo low win ing g

is swif swifte terr

is

at a ben bend

prev pr evio iou us

ban k,

curr cu rren entt and

of the

par artt

aga ag ainst

inner

the th e

but the the

parts

cen ce ntr tra al

flo fl owin ing g the th e

Gil ilbe bert rt sa says ys::

On arriv arriviing

swifter

upper

not

a sh sho oal cross

its

sides

to run run

fro rom m

but the

the is in-

ner bank of one curve to t he he inner bank of t he he other. In mea ean nde deri ring ng stream stre amss it is usua usuall lly y nar arro row w and and is a app ppro rop pori ri-ately are

in

in di direct ctiions

its

slope

greater

mea ean ndering

sides

of co course,

channel is

in an an

and an d meandering

fine fi nen nes esss

chan ch ann nel

near

belo be low. w.

change

the th e a

that

be of

dis isti tin nct ctio ion n

general is

slo sl ope

by a strea stream m,

It r es esults

overov

of

slopes

main

may

If th the

winds

Commen enti ting ng on the cu curv rvat atur ure e of a chan channe nel, l, wh ich grea gr eatly tly co com mpl plica icate tes s the th e transp transport ortat atio ion n and an d dep depos ositi ition on

met etrric,

parts. above

gentle lerr

wit ith h

Thi hiss

amount.

stre rea am

and some

stre st ream am

Bec ecau ause se

in the the

the

course

separated

gen ener eral al

true

entire en

stre st ream amss

capacit ity y

strream st amss

or

its

course se,,

mag agn nit itu ude

the th e

the

of

alluv all uvia iall

are

larg la rge. e.

whic ich h,

apply

to

from points If th the e

by

corroding,

are ar e

is of of

which

which

thu th us

rather

bed ed..

bed

or al allu lu--

courses

as

alluvial

up th the e

is usu usual ally ly

the

forr fo

tha th an

hav ave e

grade. and

than th an

bed

of 

rest re stra rain in

of deb debris

shift

strea str eam m's

a s tr tream

and

wal allls

the th ese

cree cr eeks ks

of deb debri ris. s.

gradation; aggrade

habit

if th the

of deb debri ris. s.

str tre eams

process sse es

supp su ppli lies es

partic icu ula larr cl asses

with

by th the

deb ebri riss

to

of deb debri s br brought and

or

wholl lly y

beds

In str striictn tne ess ss,,

buil ild din ing g

The

cha ch annel

con co ndit itio ions ns

of

stream

rea eac ched

dep epo osi site ted d able

sev se ver eral al

wherev eve er

is

and an d other otherwi wise se

with

are

courses

condit itiion

or abrades,

not

hav ave e

widt wi dth h

and an d many many

supply

is mad made, e,

called

said

of

their

by the

sults.

str tre eams

or alluvial alluvial..

When ene ever

tha th an

thei th eirr

Mos ostt ri rive vers rs

ports

tax ta xed

limi li mitt

The Th e

its

bedrock .

wears, is

of deb debris

by sp speak akiing

phases

stre st ream ams. s.

rock

bed edrrock

streams

be ind indica catted

if the

than

of deb ebri ri s eq equ ual s or exc excee eed ds

Most

ban ank ks.

rock-walled,

the

less

rea re ach che es

of pre previ vio ous usly ly

these

and an d

is

bed is co con nst stit itu ute ted d

beds

rigi ri gidl dly y

bed ed,,

sup su pply

strream st

with

a stream

curren entt

over

the th e

to itss it

the

load

The

ang an gular

gentle le,,

or more more..

direct dir ect

two

move vess

debris

dragging

is

to

of de debr brii s tra trans nspo port rtati ation on..

capa ca paci city ty

in

accord rdin ing g

charac cha racters ters::

class ssiifi fic cati tio on

When the

to

stre st rea ams

in the te term rmss

by

depth

180 18 0

by an an al allluvial str tre eam is relatively direct and tth he

are of sm smal alll

part 0

thro th roug ugh h

dete de term rmin inin ing g

weight

den enssit ity y

but the the

relation

current

to

the th e st stre ream am..

bei ein ng

by t he he

swin sw ing g

al so

An imp impor ortan tantt

effic iciiency

far

greate terr

a gre grea ater

grav gr avit ity y

nat atu ure

of

coar arsse.

unde un ders rsto tood od..

between

the th e

and

a fa facto torr,

manner;

if the

the

left

is rel relat atiivel ely y

to th the gen ener era al

place

than

and

tract ctiion,

also

likewise

fram

carried pow po wer

of

affe fec ct

and th the eref efo ore ture

is

chan ann nel el,,

fri ric ctio ion n

vi sc scos osit ity y

is

a low low speci specifi fic c

curvature

The

velocity

carr ca rry yin ing g tha th an

part rtiicle less

in for form of of

and

of

and

slo lop pe

intric ica ate

wit ith h

and an d

to ri right

general

slope desce cen nded its course is

opposite

Bed velo veloci city ty

incr in crea easi sing ng

prev eva ai Is, Is,

the th e

carr rriied

bed be d.

bends

general steep,

a

is

great atlly

by di scharge

debris

parti tic cles

being

The

diversity

ta

a bro broa ad

Velocity

var ariies

the th e

affe fec cte ted d

more

a fac factor;

one.

If the relatively

the the

cert ce rtai ain n

of a str stream

by de dept pth h,

everywhere

the th e

of fi fine

alon al ong g

also.

is

is

velo loc ci ty ty

Size of

and

bed,

is

car arrried

of

bri rief efly ly

capacity

a n ar arrow

vel elo oci city ty

slope

rea ealliza zattion

Width

debrris deb

an d de depth

over

aver era age

is

of

the

bed ed..

than

in th the e by

by sl slop ope e.

its

more

quan anttit ity y

Some

by co consi sid der erin ing g

modify

debr de brii s al alon ong g

channel

the th e

complica co cattion.

conditi tio ons

tran tr ansp spor ortt

is

a

may be achi achiev eved ed

cal allled apt

a ba bar'.

In di dire rect ct

to be be sep separate ted d

is usual allly

broad

wi dt dth h of th the e

and

chan ch anne nell.

allu al luv via iall

by lon long,

stre st ream ams, s,

nearl rly y

may for a dis distance

wher ere e

strraig st igh ht occ ccu upy

ben end ds

rea eac ches, the entire

it

Deposition

The Th e na natu ture re deta de tail iled ed

of str strea eam m

stru st ruct ctur ure e

text te xtbo book oks, s, depo de posi sits ts,,

of comp compli lica cate ted d

espe es peci cial ally ly

comp co mple lex x pro roce cess ss

by sid side

com co mplex exit ity y

with and an d

cons co nsta tant ntly ly

dro rop p

while

they

up

pick

its

goin go ing g are ar e

away aw ay

and on.. on

surface.

the a

point,

rock ro ck

This

wher wh erea eass

oppose sed d

the

eros er osio ion n

other,

is

they

can ca n

howe ho weve ver, r, more

is we well ll kn know own, n, an and d gi give vess

or les less

stre rea am

dupli lic cate ted d

is checked

the th e mater materia ials ls slope slo pe

are of fi fin ner gra rain in

cles cl es

car arri ried ed

deep de eper er

wate wa ter. r.

The all llu uvium

and

deposit itss.

water

and

to dro drop. p.

The Th e

emba em bank nkme ment nt..

the th e

slo sl ope are

bed be ds

deposited

makes

The

up

term

and an d dep epo osi site ted d composed

by fan, fa n,

a

cessive

is

a seri series es

of a loa loade ded d

of co coa ale lesc scin ing g

allu al luv via iall

A del elta ta is th the e fi fin nal depo posi sitt it ente enters rs

and delta used

bord bo rder erin ing g

a

cutt ttin ing g of

levee lev ees s

onto

to be Lat ater eral al

on the the out uter er

on the the in insi sid de, the th e

vall va lle ey.

the th e cutt cuttin ing g ing oxbow

alo lon ng

is

a val valle ley y.

unlo un load aded ed

swin sw ingi ging ng

side si dess

as

fies anastomotic

low rid ridges

in the the wid wid-

stre st ream am

itse it self lf

the th e pr proc oc..es esss

may de-

in pl plac aces es

by

form fo rm--

A st stre ream am whic ich h fo form rmss a on its its

floo fl oodp dpla lain in

An ov over erlo load aded ed

typi ty pi--

stre st ream am on a

low gra low gradi dien ent, t, be beco comi ming ng chok choked ed,, an and d const constan antly tly to cut cut ne new w chan chann nels ls,, dev de vel elo ops an in intr tric ica ate on a flo flood odpl plai ain; n;

and

is te term rmed ed braiding.

obliged oblig ed netw ne twor ork  k 

a

and

the the

resu re sult ltan antt

dep de pos osit itss

from fr om th thos ose e The

call ca lled ed

ponents

are ar e sand,

rar are. e.

spa sp aci cin ng

tai ain n

sid ide es.

with

sto ton nes

smal sm alll

glac aciier erss

coa co ars rse e

talu ta luss

be

of

any an y

have

the

som so me

tha th at

the

wholl lly y

unst stra rati tifi fied ed

till ti ll is

Such Su ch

sto st one nes, s,

fro rom m

lik li ke

It is is ofte often n bee een n

much

the th en

be

abo ab ound till

in the the

Shas Sh asta ta

and an d

with

typical of th the

sto"es,

volc lcan aniic

bould lder erss

dep epo osi sits ts

of 

swee eep p

the

ang an gular

but man many y

It

is

usual

to fi find

ras asp ped

alo al ong

the

be well well po poli lish shed ed..

cove co vere red d

bed edss

Rai aini nier er..

wit ith h

scra sc ratc tche hess

stream ari rid d may ma

gravel

reg egio ion ns. or be

mudflow

dep epo osi sits ts,,

on the the

and

Unles esss

unle less ss almost

Nev evad ada a containing

one

this th is dep de pos osit itss

are ar e

gene ge nera rall lly y

sand, fin ind ds

impossible

such su ch

as

fail fa ilss

as Mts ts..

are ar e

seld se ldom om alluvial

top to pograp aph hy

ple len nty to

large

inte in terb rbed edde ded d

in t he he

surrfa su face ce

as as

flan fl ank ks,

crit cr iter erio ion n

mou oun nta tain inss

are

such

its

Even Ev en

the th e

It may may

which

Sie ierr rra a

by

mud udfl flo ow and an d

if it it has has

exposed ed..

dep epo osi sits ts

rock ro cks. s.

Ord rdin inar ary y

esp spe eci cial allly

bouldery

volc vo lcan anic ic

mora rain ines es

til illl,

or is poorl rly y

distinguished

occ ccu upi pied ed

pre resser erv ved it

other

nonvol nonv olca cani nic c

as glaci glacial al

fan anss stiill st

wit ith h

be

gla laci cier erss

as thic thick k

sprrin sp ink kle led d

the

in till may

may ma y thus thus

to iden enttify

Miocen ene e

often of

well

sto st ones

by bei bein ng

or ero eroded

Fro rom m

qua uant ntit itie iess whe here re

to

rounded.

upon

of the the mo moun-

more th tha an

wel elll-ro rou unded

are ar e

depen end ds

of th the

The

bedr be dro ock ck,,

diff ffic icu ult

con co nfu fuse sed d

may

lit ittl tle e

Har ard d ro rock ckss

the th e

not

case ca sess

true

bevel elle led d

in

are

mas asss

sto top pes es..

edges

feet

five

rock ro ckss

in som some

done

to

or more

of 

recog rec ogniz nized. ed.

deca cay yed

unstr trat atif ifie ied d.

but

val alle ley y

and

the th e

of  

com co m-

mas asss

boulder erss

in

type its

order erle less ss

feet

is an ~ar ~arth thy y

hav ave e

bee een n

are easil easily y

of suc such

par arti ticu cullar arly ly

fro rom m th the

hav ave e

25

one and an d

three

those

size si ze

bott bo ttom om of th the e gl glac acie ier. r. which wh ich

Blocks

and

which

sha sh ape

who

agen ag enci cies es..

only

- a jum jumbled

bould lde ers

corhers

and an d other other

It is is

join jo intt-c -cra rack ckss

This

depo de posi sits ts

be dis isti ting ngui uish shed ed

leaves

Usu sual ally ly

pre red domin ina ate te..

of gl glac acia iall

Blac Bl ack kwel eld der er,,

shou sh ould ld

lake la kess

boulders.

and an d

depo posi sits ts

engi en gine neer ers. s.

glacier

the

of

fans. fa

thei th eirr va vario rious us

of glaci glacial al

by gla glaci cier erss

common

In gener eral al,,

the

dece de ceiv ived ed

by Eli lio ot

unso sorrte ted d

and

are

of

thos th ose e

of a

till.

quite

Suc-

stud st udy y of th them em::

left le ft

tongue

depo de posi sitt

hav ha ve

in a su surf. f.''

uns nso ort rted ed

char ch arac acte ters rs

made ma de by str strea eams ms,,

ice

Mud udfl flow owss

building

muc uch h like like

sum su mmar ariz ize ed

hass ma ha made de a spec specia iall The Th e

the

and an d

Obs bser erv ver erss

cork co rkss

in

and an d have have fr freq eque uent ntly ly

clea cl earl rly y

clay,

'lik 'l ike e

to

it liq liqu uef efie iess

powe po werr of mu mudf dflo lows ws,,

The Th e di dist stin ingu guis ishi hing ng are

It ad ad-

pp-7 pp -78.) 8.)

have ha ve ma many ny chara charact cter eris isti tics cs depo de posi sits ts

hea eav vy

flow fl ow of lava lava..

p ar art

an..d Flin an Flint, t,

afte af terr

too visc visco ous

it unt until il

in dia iame mete ter. r.

bobbing

play

Knop Kn opf, f,

pecu culi lia ari riti tie es,

of a st stre ream am

up of th the e mea ean nder ers, s,

netw ne twor ork k

drai dr aina nage ge..

wil illl

of the the cur urv ves

whi hich ch re resu sult ltss

as a re resu sult lt..

inte in terl rloc ocki king ng

flo loo odplain

up as

A mea meand nde eri rin ng

off and and si silt ltin ing g lake la kess

its

buil iltt

velo ve lop p to the the poin pointt of str strai aigh ghte teni ning ng

com co mpl plex ex

of ab abru rup pt

A fl floo oodp dpla lain in

by a stre stream am,,

str tre eam

the th e ch chan anne nell.

dep epo osi siti tion on enin ing g

of

natu na tura rall

cau ause sess

fla fl ats

for t he he

a stil stilll bo body dy of wate water. r.

Overflow cause

stre st ream am..

called

rock ro ckss

feet fe et

in

fine fi ne ro rock  ck 

mas asss •• ••••

it bec becomes

behi be hind nd

an adva advan nci cin ng man any y

mudflows

di ameter

flood flo odpla plain in,,

is

the

Iike Iik e

slo sl ope pess

a sli slippery

when

pro roce cess ss

only on ly whe here re

on ste steep ep as

wat ater er

The Th e tra trans nspo port rtin ing g

in

top of the

stream

fanglomerate

of

grav gr avel el mate materi rial alss of allu alluvi vial al fa fans ns.. An allu alluv via iall fan is buil fan iltt up at th the e poin intt chan ch ange ge in grad gradie ient nt

on the the

the th e

gre reat at

(Lon (L ongw gwel ell, l,

Bottomset 

down and spread out on by th the e fluctu fluctuat atin ing g stream stre am..

material

of a

and an d ar are e fo form rme ed by th the e part rtii-

bey eyo ond Topset

material s la laid id othe ot herr ma mate teria rials ls

current

to the the dep epo osi siti tio on

of th the e gr grow owin ing g

beds

whic wh ich h is

standin ing g

are ar e pe perm rmit itte ted d

is appli lied ed

out

the th e

by a bod body of

beds be ds

in a delt delta, a,

a pic pictu ture re

whenever

tran tr ansp spor orte ted d

fore rese sett term fo

front fro ntal al

depo de posi site ted d

sto top pping

boul bo ulde ders rs

the th ese

mud ud,, ca call lled ed

ope pera rati tive ve

It oc occu curs rs

downward

in wa waves es,,

carr ca rry y

of thic thick k

infr in freq eque uent ntly ly

wat ater er-s -soa oake ked d

moves

proc pr ocee eeds ds

can ca n

of one one ov over er th the e ot othe her. r.

of ma mate teri rial alss

thau th aug gh

is the the mud udfl flo ow.

flo fl ow an and d dam amm min ing g

see een n

in prac practi ti ce on Iy by by recog recogn n izi izing ng th the e pr prep epon onde derr-

The Th e ar arra rang ngem emen entt

norm no rmal al

and an d

agai ag ain n

reverse

and an d depos deposit itio ion n

to ea each

rain ra inss, vance cess

up

it is depo deposi siti ting ng

depositing

fluv fl uvia iall

pick ckiing

Ano noth ther er arid ar id re regi gion onss

enti en tire rely ly

akin ak in to landsl landslid ides es..

mat ater erii al bec beco ome mess

bott bo ttom om

is a ct ctively

it is mer merel ely y than th an

of 

curr cu rren entts,

to th the

stream

mat ater eria iall

forfo r-

is a resu resullt

str trea eam m

are ar e

be cut cut an and d le left ft in the the

with wi th on only ly a film film of grav gravel el on the the

com co mpo pose sed d

mudflows,

goes go es

may ay,, howev eve er,

and an d co cove vere red d

Stre St ream amss

such su ch as thos those e

frag fr agm men ents ts

When

actively

physi sica callly

be separ separat ated ed once on ce

it i s

Ther Th eref efor ore e

of

rock ro ck

others.

mor ore e

when

pro roc ces esse sess

foun fo und d in gra grave vell

dep de pos osit itio ion n

ero rossio ion n.

some so me

bed at a cer certa tain in

and an d ca carr rryi ying ng there,

flu luv via iall vari riab abiili litty

whic ich h ero rod din ing g

bedr be droc ock k

depo de posi sits ts

of fl fluv uvia iall

The ben enc che hess

to expl explai ain n

deta de tail il

feat fe atur ures es

If the the st stre rea am is re reju juv ven enat ated ed and th the ere refo fore re cuts terraces deeper,, deeper floodp flo odplai lain n or benches are for forme med. d.

in var vario ious us

regi re gion on lik like e th the e Si Sier erra ra Ne Neva vada da..

con co nst stru ruct ctiv ive e

ward sid ide e

and an d th thei eirr

and an d te text xtur ure e ar are e de desc scri ribe bed d

of a mo moun unta tain inou ouss

the

depo de posi sits ts

butt not bu not wi with th su suff ffic icie ient nt

alll th al the e ty type pess

The Th e

or flu fluvi vial al

of

is

scra sc rattch ched ed

d is istinguish

till

fro rom m la lan ndsli lid de dence

can

dumps.

In many

be rei i ed ed on,

and an d wei eigh gh th the e im impo port rtan ance ce The

riv ive ers

gra rav vel,

whic ich h

the th en

weakens

fin fi ne

near

gra rade dess given gla gl aci cia al

stre st reom omss

are ar e no norm rmal ally ly scra sc ratc tche hed. d.

To

can ca n trace trace

larg la rge e the

grav gr avel el

glac gl acia iall

mora mo rain ine e

hist hi story ory

of the the dis distri trict ct..

The tive.. tive

lotter lo

laye la yerr the th e

mad ade e

lik ike e

in cross-sectio ion n.

most

cont co ntai ain n

lake

been

lake la ke..

Thes Th ese e

lof pea peat that th at

from

lam la min inat ate ed

or ch cha alk lky y

stra st rati tiff

in ge gene nera ral. l.

In qua uant ntit ity y

oth the er

deposit itss

lake

larrge la

quanti titi tie es

the th e de delt ltas as Oth the er such

as

rath ra ther er

lan la ndslid ide es,

talu luss,

boul bo ulde ders rs

lake la ke..

depo de posi sits ts

forr fo

the

over

and

They

Str trea eam ms

and

of delt delta as exc ex cee eed d

glacial

riv ive ers

the th e carry

lod lo dges

in

lake la ke..

in gla glaci cia al fans,

local

ente en terr-

of grav gravel

ofte of ten n

all llu uvia iall

are

the beds be ds

by or orga gani ni sms sms

all of wh whic ich h

be form formed ed

whi hich ch

wit ith h

form fo rmed ed

com co mpo pose sed d

detr trit itu us

may

spec sp ecifi ifica callly.

commonly

is cha chara ract cter eris isti tic c

the th e delta delta

that th at

clays floating

than th an up upon on th the e fl floo oorr of th the

depo de posi sits ts

desc de scrib ribed ed

ica ic ati tion on

coarse

Un-

of th the e

delt de ltas as

as the

than th an

ice

eart ea rth h

tha th at

seas se ason on..

lak la ke

of

down

bond bo nded ed

may be as asso soci ciat ate ed

gre rea atly ly,,

of

are la laiid

in col color or

cakes

part pa rtss

dist di stin incc-

dark da rker er

smal sm alll

diat di ato omac aceo eous us

the th e

rath ra ther er

melt ltin ing g

and an d even even

loke lo ke fo form rm adv advan anc cin ing g

in whi hich ch

glacial

cla cl ays

the th e cl clea eare rerr

are ar e

and an d

one on e

wit ith h a

the th e ph phys ysio iogr grap aphi hic c

com co mmon only ly

sum umm mer

the th e

pebb pe bble less

dropped

inha in habi bite ted d

ing in g the the sand sa nd

deposits

scat sc atte tere red d

have

the th e

a non-

unle un less ss

is due due to th the fa fac ct

is fine finerr

duri du ring ng

from

and sil iltt

are ar e

This

in win inte terr

loid lo id do dow wn

clay

whi hic ch

boul bo ul-in th the e

conn co nnec ecti tion on

lak la kes

lake,

or

abse ab sent nt..

a g la lacial

into in to actu actual al

shee sh eets ts

smal sm alll

impo im poss ssib ible le,,

in gla glaci cia al

of th the e

in th thin in

depo de possit ited ed one on e

of

pebble less

str tra anded

are ar e gene genera rall lly y

and an d ofte often n

terr te rrac aces es

On the the botto tom m

se''en se

deposits

separate face fa cete ted d

Alt ltho houg ugh h

becollJ lJe e

of  

usu sual ally ly

The

eith ei the er

or can can wor ork k ou outt in deta detail il

depo de posi sits ts

very ve ry ev even enly ly

and

boul bo ulde ders rs

is dif diffi ficu cult lt

the th e

are ar e rare. rare.

cakes

at a

those

into

sizes.

and an d ve very ry ra rare rely ly

ston st ones es

beca be caus use e

thou th ough gh

sort rte ed

of vari vario ous

three

to tim time e

g en eneral,

well

grav gr avel el,,

rive ri verr

in

are

distinguish

glac gl acia iall

deposits fair fa irly ly

These

inte in terb rbed edde ded, d,

gra rav vel

by ice ice

curre ren nt

the

from fr om tim time e

and

Angu gula larr

rive ri verr

or less less

pow po wer oc occu curr

rou ro und nded ed

coarse

as

mountains.

They wel elll

of ev evi-

a I I t he he fact s

deposit

sand

stra st rati tifi fied ed,,

are ca carr rriied

glac gl acia iall

glaciers

dist di stin inct ctly ly

of sand

typ ty pe

study

fin ina all lly y t he he

mor ore e

river

are ar e

cross-bedded.

ders de rs

of

are ar e

Like

fro fr om and

in th the e ri rive ver' r'ss

place.

lay la yers

issue edge

of detr detrit itus us

vari va ria ati tion onss

no one

must

of eac each. h.

gra rav vel,

the

cases

but one

vall va lley eyss,

need

not be

and g en enerally

well

known.

The deepenin ing g gravels sno sn outs the th e

gla laci cial al

canyons

by outwash of gla lac cie iers rs

rob ro bbin ing g

grav gr avel els. s.

of

and

stre st rea ams

which

dest stru ruc cti tio on

of earl rliier

stre st ream ams s

of

carr ca rrie ied d the

at th the e poin intt

forn fo rnia ia to a larg large e

gold go ld-d -dre redg dgin ing g

exte ten nt

owes

its it s

from th th e chap ch apte terr

in

goldgo ld-be beari aring ng Nev evad ada a

was

slo lope pe of th the e ra ran nge

where th the e majo jorr ri riv vers

The ex exte tens nsiv ive e

of 

by Ple Pleii stocene

Sier Si erra ra

dum du mpe ped d at th the e fo foot ot of th the e wes este tern rn Valley Valle y.

iss is sue

form fo rm a ve very impo porta rtant nt

Muc uch h of of th the e mat ater eria iall out utw was ash h

and th the e deposi siti tio on

ente terr

the th e Gre rea at

grou gr ound nd of Cal alii-

exis iste ten nce

to th the ese

streams stream s. So fa farr as th the e pro roce cess sses es are ar e con once cern rned ed, stu tud dy

of

throu thr ough ghou outt

invo in volv lved ed

much ca can n be ga gain ined ed

ancie ien nt the world world,,

gla lac cial

stre st rea am

especiall pecially y

in strea stream m ac acti tion on by th the e det etai aile led d channels

in its its

north the ern

found belt lt..

Phys Ph ysio iogr grap aphi hic c

Term Te rmss

Rela Re lati ting ng

to St Stre ream amss

The mere defi fin nit itio ion n of som some of th the e te term rms use sed d in stream stre am ph phy ysi siog ogra raph phy giv gi ves a dir direc ectt , in insi sig ght in into to th the e science.. science

Cycl Cy cle e of Er Eros osio ion n in inc clu lud des the th e se sen nes of cha changes from fro m the initial cutti tin ng of a surf rfa ace to th the e fi fin nal re re-ducti tio on of a region to a baselevel. The su surf rfa ace of a regi re gio on re redu duce ced to fair fairly ly lo low w relie relief, f, but st stil illl undu dula latting, is called a peneplain (a (also lso sp spel elle led d peneplane). It is a sig signif ific ica ant fac fa ct th tha at th the e Sie ierr rra a re reg gio ion n in earl early y Ter erti tiar ary y ti tim me was ap app pro roac achi hin ng th the e pen enep epla lain in st stag age of  eros er osio ion n, when the ar area ea was cov over ered ed wit ith h la lav va to form form a mor more e near arly ly pla lain in-l -lik ike e surf su rfac ace, e, an and d la late terr upli lift fted ed. The upli lift ft ca caus used ed de deep ep d. d .isse issectio ction by stre stream ams.

Stages of st stre rea am develo lop pment, fro fr om gull gulle eys to youth uth,, matu atu-com co mpl plet etel ely y wor ornd ndow own pl plai ains ns,, cons co nsist ist of  yo rity, an age, e, with con and d old ag contin tinuo uous us tra trans nsiti ition onal al stage sta ges s betw be twee een. n. The ear early ly stages stages re repr pres esen entt ve very ry ra rapi pid d gr grow owth th,, whic ich h slo low ws down graduall lly y unti till at old age th the e chan ch ange ges s may be extre extrem mel ely y slo slow w. The genesis or orig origin in of the str strea eam m ta tak kes in into to co connsidera sid rati tio on the th e in init itia iall su surrfa fac ce over whic ich h th the e st stre rea am first fir st flo flow wed ed.. Se Seve vera rall te term rms s are use sed d by geo geolo log gis ists ts in ons sequent  st rela re latio tion n to this this su subj bj ec ectt . C on stre ream ams ar are e th thos ose e who hose se po posit sitio ions ns wer ere e de dete term rmin ined ed by th the e initia initiall sl slop opes es

Subsequent  st Subseque of th the e la lan nd su surf rfac ace. e. stre rea ams are whic ich h are est sta abli lish she ed by grow rowin ing g headward belts of weak rocks.

those tho alo lon ng .

Whe here re the the unde derl rlyi ying ng st stru ruct ctu ure res s of th the e ro rock cks s ha hav ve aff ffe ecte ted d th the e dir ire ecti tio on of th the e st stre rea am and it its s vall lle ey, struc uctur tural al co contr ntrol ol.. The the stream is said to have str faul ult, t, jo join int, t, st stri rike ke,, an anti ticl clin inal al,, sync sy nclin linal al,, an terms fa and d monoclinal are pre refi fix xed to the the word 'v 'va all lle ey'; thu th us,

  faul faultt-va valle lley, y,

stri st rike ke-v -val alle ley, y, etc et .c It is is es esp pec ecia iall lly y sign si gniificant th fic tha at th the e ri ric chest gold ld-b -be eari rin ng channels have stru st ruct ctu ura rall con co ntr trol ol-the th e stre stream ams ori rigi gina nall lly y ra ran n on and and alon al ong g min iner eral aliz ized ed zo zone nes s in bedr bedroc ock  k .

Str tre eams may st star artt th thei eirr· cours rse es over one so sort rt of  geolo log gic ica al form fo rmati tio on, but as ti tim me pro rog gre ress sse es the th ey lett do dow wn on a lo may cut th thro rou ugh it and be le low wer and entir en tirel ely y di diffe ffere rent nt ty type pe of stru struct ctur ure e; such su ch st stre ream ams ar are e said to be superimposed  (o (orr si sim mpl ply y superposed) on the th e un und der erly lyin ing g ro rock ck st stru ruct ctur ure. e. Whe hen n a cert certai ain n st stre ream am  pattern, or orig igin inal ally ly dev de vel elop oped beca caus use e of pre previ vio ous topo to pogr grap aphi hic c or st stru ruct ctur ural al co cond nditi ition ons, s, is reta retain ined ed ev even en aft fte er those condit itiions are removed, the str tre eam is said sa id to hav have e inher it ed  it its s pe pecu culia liarr fe feat atur ures es fr from om muc uch h earl rlie ierr peri rio ods of it its s li life fe..

permane ent . DepresStre St ream ams may be intermittent  or perman sion of topo sion topogr grap aphy hy al alon ong g a coas astt may caus e th the e se sea a to in invade th the e vall lle eys, and th the e st stre rea ams are drowned. Upri rise se alo lon ng th the e coast may le lea ave hanging valleys. Tri rib buta tari rie es to a main st stre rea am whic ich h has been much fast fa ste err-c cutt ttin ing g may als lso o be left left 'h 'ha angin ing g'; as, fo forr exexample in Yose sem mit ite e Vall lle ey where th the e si sid de st stre rea ams rea re ach th the e Merc rce ed Riv ive er by way of beauti tifu full wate terrfalls. longitudi itudinal nal pro profile file of a st The long stre rea am is ta tak ken fr fro om its it s so sou urc rce e to its its mouth th,, whil ile e it its s gradient  represents

its in its inc cli lina nati tion on at som some pa part rtic icu ula larr part pa rt of it its s co cour urse se.. Tri rib buta tari rie es are sa said id to be be accordant  whe hen n th they ey en ente terr at about the same level as their main stream. A grade de when rat stre st ream am is said said to be at gra rate e of de degra grada datio tion n and ra rate te of agg ggra rada dati tion on ar are e abou outt eq equa ual . A stre strea am whic ich h is able to main inta tain in it its s cours rse e, even when a segm even segmen entt of th the e ea eart rth h is gr grad adu ual ally ly ra rais ised ed ath thw wart th tha at cours rse e, is call lle ed an antecedent  stream. If,, however, th If the e upri rise se of th the e mounta tain in cause ses s th the e flo fl ow of of th the e st stre ream ams to be be acce accele lera rate ted d down its sl slop ope so that they cut deeper gorg rge es, they are said to be be Even stre stream am meanders. deve de velo lope ped on a rejuvenated . plain, plai n, may be entrenched  or incised  de dee epl ply y, win indi ding ng ca cany nyon on by elev elevat atio ion n of the plai plain. n.

to form form a

Rej eju uve vena nati tion on may be ef effe fect cted ed in oth other way ays s th than an mountain-mak mountainakin ing. g. Chan ang ge of clim climat ate e may make a dedecid ci ded chan ange ge in st stre ream am cutt ttin ing. g. St Stre ream am piracy is anoth ther er impo import rtan antt caus use. e. Thi his s co con nsi sist sts s of the the capture of 

Many clu lue es as to the the geolo log gic st stru ruc ctu ture re and his is-tory to ry of th the e un und der erly lyin ing g re regi gion on ar are e gai aine ned d by the the st stu udy of stre stream am pa patte ttern rn,, fro from m ei eith ther er an inte intens nsiv ive e or reg regio iona nall poin intt of vie iew w. In the nort rth hern Sie ierrra Nevada, the stre st rea am patt tte ern develo lop ped pri rio or to volc lca anic acti vi ty was st stru ruct ctu ura rall lly y cont ntro roll lled ed by bed bedro rock ck; butt durin bu during g the th e la late terr peri rio od of volc ani sm it su suff ffe ere red d change by that th at wid ides espr prea ead d acti tivi vity ty.. The maj major or st stre ream ams su subs bseequent to volc volca anis ism m fo foll llo owed th the e sl slo ope of th the e la lav vacove co vere red, d, til tilte ted, d,

and an d uplift uplifted ed

faul fa ult-b t-blo lock ck

An inst instru ruc cti tiv ve outl tlin ine e of th the e patt pa tter ern n is giv given en by Em Emil ile e Zer ern nit itz z

rang ra nge. e.

subj ect of st sub stre rea am who de desc scri ribe bes s and

illust illu stra rate tes s by many ac actu tua al ex exa ample les s su such ch pa patt tte ern rns s as follows: dend de ndri riti tic, c, trel tr elli lis. s. rect re ctan angu gula lar, r, ann nnul ular ar,, radial, and parallel. He st stat ates es th tha at: The pa patt tter erns ns whi hich ch st stre ream amss form fo rm are are dete determ rmin ined ed by ininequali equa liti ties es of sur surfa fac ce slo lope pe an and d in ineq equa uali liti tie es of roc rock k re resi sist st-ance an ce.. Thi hiss be bein ing g tr true ue,, it is is evid eviden entt tha th at dr drai aina nage ge patt pa tter erns ns may re reffle lec ct orig igiinal slo lop pe and ori rig gin ina al stru ruc cture or may refl re fle ect the th e successive epis iso odes by wh whic ich h th the e surf rfa ace has been mo modifi fie ed - includin ing g uplif iftt, depressio ion n, tilt ti ltin ing g, warp rpiing, folldin fo ing g, faulti tin ng, and join inttin ing g, as well as dedeposition by t he he sea, glaciers, volcanoes, winds, and rivers. seve se vera rall

498).

A single of the these se

drainage fact fa ctor or''s.

pattern (Journal

may be be th the r es esult of 

Geol Ge olog ogy, y,

vol. vo l.

of  

10,, p. 10

Diagram to show a meandering stream with oxbow loopss. Suc loop uch h a str strea eam m de dev vel elop opss in a va vall lley ey wor orn n dow down in base ba se-l -lev evel el and an d not not subj subjec ectt to ex exte tens nsiv ive e floo fl oods ds..

one st stre rea am by another. The second lie ies s at a lo lower elev el evat atio ion; n; it its s he head ad cu cuts ts ba back ck unti till th the e fi firs rstt is tap tapp ped ed,, or beheaded. Then th the e wate terr fr fro om th the e fi firs rstt st stre rea am, fro fr om tha that poin intt upward, is caused to flow into the cap aptu turi rin ng st stre ream am. In this this manne nerr th the e fl flow ow in the fi firs rstt

Dia iag gra ram m to sh show ow a subd subdiv ivid idin ing g in a val valle ley y su subj bjec ectt to fl floo oods ds..

or anastomosing

stream

is accelerate ted d oft fte en to such an exte ten nt that a new gorg go rge e may be form formed ed.. Who hole le str strea eam m sy syste stem ms may thus thus be readjusted  and re rep peate ted dly go th thro rou ugh new li life fe cycle les. s. Pir ira acy and st stre rea am adju just stm ment were apparently ve ently very ry ac activ tive e in the Si Sier erra ra Nev evad ada a du durin ring Ter ertia tiary ry tim ti me; th this is pro roc cess part rtly ly accounts forr many of the fo the deep de ep ac accu cum mul ulat atio ions ns ther th ere e of Ter ertia tiary ry gr grav avel el.. The pattern of an individ idu ual stre rea am, or of the the whole or any part of its sy syst ste em, develo lop ps in its own pecu pe culia liarr way bec becau ause se of cert certain ain co contr ntroll olling ing ge geolo ologic gical, al, topo to pogr gra aph phic ical al,, and clim climat atic ic feat fe atu ure res. s. The patt patter ern n, the th ere refo fore re,, is a cha chara rac cte terr sig si gnif ific ica ant enough to bear Spe peci ciil illl st stu udy and to su supp ppor ortt man any y new des escr crip ipti tiv ve terrms. It is now best stu te tud die ied d by means of ae aeria iall photogra photo graph phs, s, maps once expression.

thoug tho ugh h de detai tailed led top topog ograp raphic hic presented the only bases

and geo and eolog logic ic of acc accurate

The fa fac ct th tha at la lak kes fi fill ll depre ress ssio ion ns, basi sin ns, and vall va lley eys s al alo ong st stre ream am cou ours rses es,, and an d th that at th thei eirr depo posi sits ts are inti tim mate telly ass sso ocia iate ted d with those of str tre eams, makes th the eir st stu udy in inte terr rre ela late ted d wit ith h th tha at of st stre rea am chan ann nel els. s. The so-ca so-call lled ed 'pip 'p ipee-cl clay ay'' depo de posi sits ts,, whic ich h near ne arly ly al alw way ays s immed edia iate tely ly over ov erlie lie th the e go gold ld-b -bea earin ring g gra rav ve Is Is,, re rep pre rese sen nt beds of si silt lt and fi fin nely div ivid ide ed volc lcan anic ic as ash, h, whi hich ch ha hav ve se sett ttle led d in lak lakes es an and d form formed a se seri rie es of th thin in la lay yers rs.. They oft fte en conta tain in impre resssion si ons s of lea leave ves, s, sho sh owin ing g th the e cha hara ract cter er of th the e fo fore rest sts s that th at gr grew ew in th that at ea earl rly y per erio iod. d. Thi his s fe fea atu ture re in indi dic cat ates es that th at befo fore re th the e vo volc lcan anic ic fl flow ows ca cam me to cov cover er th the em up, up, the th e st stre ream am val alle leys ys ha had d been tr tran ansf sfor orm med in into to la lake kes, s, into in to whi hich ch th the e volca volcani nic c as ash h se settl ttled ed..

A.

An exa xam mpl ple e of  dendritic drai dr aina nage ge patpa ttern rn,, wh ic ich h deve lo lop ps whe herre th the e unde underr· lyin ly ing g ro rock ckss li lie e in a ho hori rizo zont ntal al posi po siti tion on and an d offer offer un unif ifor orm m re resi sist stan ance ce to ero erosi sion on..

Diagr gra ams to il illu lusstr tra ate thre th ree e successiv ive e sta tag ges in st stre rea am  piracy.  piracy. The stre rea am cutt ttin ing g back at the the lo low wer ele lev vatio ion n behead he adss an and d ca capt ptur ures es the th e st stre ream am fl flow owin ing g at a hi high gher er le leve vell .

In gen gener eral al,, Str tre eams te ten nd

a lak lake is not not as long long-l -liv ived ed as a stre stream am. to dest stro roy y la lak kes, eit ith her by gra graduall lly y

fillin fill ing g th the eir basi sin ns wit ith h detr trit itu us or by cutt ttin ing g down their outle lets ts to a point where their basins may be dra rain ine ed. Someti tim mes, however, lak la kes pers rsis istt lon lo ng enou oug gh so that that th the e ar are ea whose dra rain inag age e th they ey re rece ceiv ive e is worn down to a local an and d tem tempor porary ary bas basele elevel vel~ ~ Lak akes es ar are e fo form rmed in a num numbe berr of ways ways:: by land landsli slide des s acro ross ss st stre rea am cours rse es; by lav lava fl flo ows whic ich h dam up up the th e dra rain ina age! by th the e down-f -fa ault ltin ing g of se seg gments of  the ea the eart rth h whic ich h ar are e th then en fi fill lle ed wit ith h wate ter; r; by gla glac cia iall actio ion n, eit ith her by scooping out rock basins or by by dam da mmin ing g wit ith h ti till ll;; by pec pecul ulia iarr ac acti tion on of ri rive vers rs th them emselv se lve es, suc su ch as si silt ltin ing g off oxb oxbow lo loo ops in a me meanderi de ring ng co cour urse se.. An exc excel elle len nt pap aper er,, now out out of pri print nt,, was wri ritt tte en by th the e la late te Dr. W.M. Da Davis is.. It not only disc di scus usse ses s the th e pre prese sent nt na natu tura rall la lake kes s of Cal alif ifo orn rnia ia,, but the th e or orig igin in of lake lakes s in gen ener eral al.. (C (Cal alif ifor orni nia a Jo Jour urnal nal of    Min Mines es an and d Geolo Geology gy.. vo vol. l. 29, pp. 175· 175·236 236). ).

B.

An exa exam mpl ple e of tr trel elli liss drai dr aina nage ge patt pa tter ern, n, which whic h de deve velo lops ps in fo fold lded ed ro rock ckss diff differ erin ing g in degrees of resistan anc ce to ero rossio ion n. The stream courses are therefore structu stru cturall rally y control con trolled led..

In the desert, the processes of erosion and of  of  strea stre am acti tio on dif iffe ferr very much fr fro om tho those in mo more humid ar area eas. s. Onl nly y quit ite e re rece cent ntly ly ha hav ve th the e ge geo olo log gic pro roce cess sses es in the des ese ert be been en gi giv ven much co con nsi side dera ra-tio ti on; so also also has much se seri rio ous tho th ought only la late tely ly turn tu rne ed to tow ward th the e poss ssib ible le develo lop pment of de dese sert rt pla lac cers on a la larg rge er sc sca ale th tha an mere 'd 'dry ry washin ing g'. The fa fact ct th that at adeq equ uat ate e su supp ppli lies es of wat water er may usual usually ly

be deriv derived ed fr from om und under ergr grou ound nd sour so urce cess in th the e de dese sert rt,, and th and the e fa fact ct th that at th thes ese e so sour urce cess ma may y be foun found d th thro roug ugh h geol ge olog ogic ical al inve in vest stig igat atio ion n and an d geo geoph phys ysic ical al surv su rvey eyin ing, g, are grad gradual ually ly bei being ng acc accept epted. ed. The most sig ign nifi fic cant ressult re ltss of recent desertproc pr oces esss st stud udie iess ar are e su summ mmar ariz ized ed by Bl Blac ackw kwel elde derr as he desc de scri ribe bess the th e fi five ve disti distinc nctt ty type pess of de dese sert rt pl plai ains ns:: 1. Pediments (in inc cludin ing g tho th ose only th thiinly vene ve neer ered ed with wi th al allu luvi vial al fans fa ns), ), wh whic ich h re repr pres esen entt the th e des ese ert slo lop pe, cu cutt in bed bedro rock ck,, in co contr tra ast to the the builtbuilt-up up th thic ick k al allu luvi vial al fa fans ns or baj bajad adas as.. Ped edim imen ents ts are ar e esse essent ntia iall lly y com co mpou ound nd grad gr aded ed floodp floo dpla lain inss exca ex cava vate ted d by ep ephe heme mera rall stre st ream amss .. .... the pediment, nat the bajada, is the normal and inevitable form developed in the arid regio reg ions ns un unde derr sta stabl ble e can candi diti tion ons. s.

2. Baja Bajada dass (co (c ompound allu al luv via iall fan fa ns) s),, whic ich h are ar e buil iltt up la larg rgel ely y as a resu result lt of dis istu turb rbe ed or inte in terr rrup upte ted d deve de velo lopm pmen entt of gr grad aded ed sl slop opes es.. Th The e upw up ward mov ove emen entt of a fa fau ult blo lock ck cau ause sess re-re newe ne wed d er eros osio iona nall acti ac tivi vity ty,, and an d thick thick gr grav avel el de de-posi sits ts are fo form rme ed by the the co con nse seq quent torr to rren ents ts and mudfl flo ows when th the ey are rele lea ased fro fr om the th eir canyons and enter a region of les lesser gradient. 3. Dried-up lake bottoms of the desert, or pla laya yas, s, whose con ond dit itio ion ns ind in dic icat ate e tha th at on onc ce mor ore e perma permane nent nt la lake kess fi fill lled ed th the e fl flat atss an and d were were fed fe d by strea streams ms th that at ar are e no now w none nonexi xiste stent nt.. 4. Di Dip p slop slopes es,, wh whic ich h ar are e broad broad plane planess de deve velo lope ped d on a denu denude ded, d, ha hard rd,, fl flat at-l -lyi ying ng or gen gentl tly y ti tilt lted ed rock roc k lay layer er.. 5. Ri Rive verr flo flood odpl plai ains ns,, whic wh ich h ar are e abnor abnorma mall de dese sert rt feat fe atur ures es,, butt which bu which we were re ap appa pare rent ntly ly mo more re wid wideespread spre ad at an ear earli lier er ti time me,, wh when en pr prec ecip ipit itat atio ion n in a giv given en re regi gion on wa wass mu much ch great greater er th than an it is to toda day. y.

A.

Blo lock ck dia iag gra ram m illu il lust stra rati ting ng Cre reta tace ceou ouss Sier Si erra ra Nev evad adan an topogr topo grap aphy hy.. The Th e upt ptur urn n ed edge gess of be bedr droc ock k cont co ntro roll lled ed the th e drai dr ain nag age e patt pa tter ern, n, whic ich h was la late terr in inhe heri rite ted d by stre stream amss of th the e ea earl rly y Eo Eoce cene ne pe peri riod od..

B.

Blo lock ck di diag agra ram m to sho show th the e ti tilt ltin ing g of th the e Sie ierr rra a Nev evad ada a and it and itss eff ffe ect on str trea eam m cuttin ing g. Erosion, pri rio or to th the tilting, planed down the surface and exposed the gran aniite te,, leav avin ing g only occ cca asi sio onal fra rag gments of th the intru tr ude ded d met etam amo orp rphi hic c rock ro ck bod odie iess as roof  roof  pendants. The stre st ream ams, s, at the the po poin intt wher ere e th they ey le leav ave e th thei eirr moun unta tain in can ca nyo yons ns and an d ente enterr th the e Gre reat at Val alle ley, y, fo form rm all alluv uvia iall fan fa ns.

Need Ne ed

forr E st fo stab abll ishm ishmen entt

of Wor Worki king ng Cr Crit iter erii

a

From the From the st stud udy y of the the co comp mpli lica cate ted d li life fe hi hist stor ory y an and d habi ha bitt of str strea eam ms an and d th the e proce process sses es invo in volv lved ed in the their ir dev evel elo opmen ent, t, a seri serie es of work workin ing g cri rite teri ria a sho sh ould be deve de velo lope ped d by the the ex expl plor orat atio ion n ge geol olog ogis istt fo forr inte interp rpre retin ting g the th e co cond ndit itio ions ns foun fo und d in the the de depo posi sits ts of all all st stre ream ams, s, incl in clud udin ing g th thos ose e of Ter Terti tiar ary y ag age e in the the Si Sier erra ra Ne Neva vada da.. GEOL GE OLOG OGIC IC

COND CO NDIT ITIO IONS NS OF

IN TH THE E

GOLD GO LD

PROV PR OVIN INCE CES S

CALIFOR CAL IFORNIA NIA

In th the e Sie ierr rra a Nev eva ada an and d Kla lam mat ath h Mou oun nta tain inss of  Cali Ca lifo forn rnia ia gold go ld-b -bea eari ring ng qua uart rtz z vein ve inss are ar e ge gene nera rall lly y found in meta tam morphic rocks not more th tha an a fe few mile mi les, s, at th the e mo most st,, fr from om int intru rusi sive ve bodi bo dies es of gra grani niti tic c rock ro cks. s. Th The e ag age e of the the meta metamo morp rphi hics cs,, whi hich ch ar are e made made up of sla slate tes, s, schi sc hist sts, s, lime li mest ston ones es,, and an d met metaa-ig igne neou ouss bodi bo dies es,, is ea earli rlier er th than an Cretac Cretaceo eous us,, name na mely ly pre pre-P -Pal aleo eo-zoi oic, c, Pale leo ozo zoic ic,, Tria Tr iass ssic ic,, and Ju Jura rasssi sic c. The ti tim me of  of  intru in trusi sion on of th the e gran granit itic ic ma mass sses es wa wass late late Ju Jura rass ssic ic.. Map of th the sa sau uth thea east ster ern n mar argi gin n of th the e Sa San n Joaq Joaqui uin n Val alle ley y showing fans built by streams which disappear after leav le avin ing g thei th eirr mou ount ntai ain n can ca nyo yons ns.. The Th e co coal ales esci cing ng alluv allu via iall fans fa ns fo form rm in this this ma mann nner er an exte extens nsiv ive e bajada.

These

earl rliier

plains

and

stream

courses

have

been covered by the the bajadas of to tod day, so th tha at tb tbe e olde ol derr ch chan anne nels ls ha have ve be beco come me bu buri ried ed in the true true se sens nse e of the word. Some of th the em may represent a lar large pot oten enti tia al pla lac cer re resser erv ve, but they they ha hav ve not yet bee een n well inve investiga stigated. ted.

The Th e quar artz tz vei ein ns were fo form rme ed sh sho ort rtly ly aft fte er th the e igneous intrusion, during the last stages of th the Jura rasssi sic c. It wou would see eem m th that at th the e met etam amor orp phic ro rock  ck  mass ma sses es we were re up uplif lif ted ted an and d intr intrud uded ed by mo molte lten n ma magm gmas as whic wh ich h

then th en co cool oled ed

and an d co cont ntra ract cted ed,,

caus ca usin ing g

the th e su surr-

roundi rou din ng and ove verr-ly lyin ing g roo ro off-ro roc cks to cra rac ck al alo ong many pla lan nes of we weak akn nes esss and to form form tho thou usa sand ndss of  fiss fi ssu ure ress. Into In to th the ese open enin ing gs the th e re resi sid dual gase ga seou ouss solu so luti tion ons, s, rele re leas ased ed from fr om th the e cr crys ysta tall lliz izin ing g gran gr anit ites es and an d co comp mpos osed ed la larg rgel ely y of sil silic ica, a, we were re inject injected ed.. Th Thes ese, e,

afte af terr so solid lidif ifyi ying ng,, wer ere e cr crus ushe hed d ag agai ain, n, an and d solut solutio ions ns con onta tain inin ing g gold go ld en ente tere red d the th e comple lex x min iner era ali liz zed zone zo nes, s, en enric richi hing ng es espe peci cial ally ly the th e cr cros osss-fr frac actu ture res s whe here re open op ening ings s were mos ostt ab abun unda dant. nt.

1. An ear earlly Te Tert rtia iarry surf su rfa ace ce,, devel elo oped an bed bedro roc ck over which whic h fl flow owed ed th the e ol old d ri rive verr sy syst stem em of th the e Co Colu lumb mbia ia basi ba sin. n. 2. Th This is su surf rfac ace, e, incl in clud udin ing g itss ri it rich ch go gold ld-b -bea eari ring ng grav gr avel els, s, was la late terr co cov ver ered ed wit ith h la lak ke se sed diments ('pipee-cl clay ay') ') consist si stin ingo goff fine fi ne silty silty vo volc lcan anic ic ash. as h.-3. And ndes esit ite e 'cob 'c obbl blee-w was ash' h' then th en co cove vere red d th the e entir entire e co coun untr try. y. 4. A ca cany nyon on was cu cutt in th this is an ande desi site te mud udfl flow ow.. 5. A ba basic lava (Iatite) flowed down this canyon as a molte mo lten n stream str eam.. 6. Afte terr this la lav va coole led d an and d har ard den ened ed,, it bec beca ame the bed of an anot othe herr rive ri verr wh whic ich h de depo posi site ted d some so me goldgold-be bear arin ing g grav gr avel elss on its surface, washed in from the surrounding eroded region. 7. Conti tin nued ero rosi sio on durin ing g the Ple leiist sto oce cen ne resu re sult lted ed in the th e wa wash shin ing g away aw ay of th the e le less ss re resi sist stan antt volc vo lcan anic ic mat ater eria ials ls,, lea le avin ing g the th e ver ery y re resi sissta tan nt lat atit ite e sta tan nding as Tab able le Mountain ta in.. Furt Fu rthe herm rmor ore, e, the th e ea earrli lier er prev pr evol olca cani nic c bedr be droc ock k surf su rfac ace e wass un wa uncov covere ered d, or resu resurr rrec ecte ted, d, expo ex posi sing ng the th e gol goldd-be bear arin ing g gra rav vel elss orig igiinal ally ly dep epo osi site ted d in th the Columbia cha ch annel system. 8. Qu Quat ater erna nary ry eros er osio ion n hass cu ha cutt ca cany nyon onss of gr grea eatt de dept pth, h, fo forr belo be low w th the e le leve vell of th the e fo form rmer er Te Tert rtia iary ry surf su rfac aces es..

The go gold ld-b -bea earin ring g vein ve ins s th thus us fo form rmed ed de deep ep be bene neat ath h the su the surf rfac ace e of the ea eart rth h, ha had d th the en to be be bro rou ugh ghtt to the the light lig ht of day day by the the er eros osi~ i~n n an and d re rem mov oval al of th the e co cove verin ring g layerr of ro laye rock cks, s, ne near arly ly tw two o mile miles s in dept depth. h. Thi his s gi giga ganntic ti c work was acc cco ompli lish she ed dur urin ing g th the e Cre reta tace ceou ous s peri pe rio od, and as a resu result lt th thou ousa san nds of lay layer ers s of sh shal ales es,, sandsto ton nes, and conglo lom mera rate tes s severa rall mil ile es in str tra ati tig gra rap phic thic th ick kness were la laid id down in an ad ad  join joinin ing g mar arin ine e ba basi sin. n. So Som me of th thes ese e be beds ds -e -esp spec ecia ially lly the th e la las st ones to be deposit ite ed - are are gold ld-b -be eari rin ng, sho sh owin ing g th that at th the e la last st par artt of th the e Cre reta tac ceo eous us eros er osio ion n fina fi nally lly re reac ache hed d th the e hi hidd dden en ve vein ins. s. Tha hatt pa part rt of the the geolo geologi gic c hi hist stor ory, y, ho how wev ever er,, whi hich ch was most importa tan nt so fa farr as th the e making of ric ich h plac pl acer er de depo posi sits ts is conce concern rned ed,, was th the e Eoc ocen ene e pe perio riod. d. The de deep ep er eros osio ion n whi hich ch to took ok place place du durin ring g th the e Cre reta ta-ceo ce ous ha had d wor orn n th the e su surf rfac ace e do dow wn to su such ch an exte exten nt that th at th the e meta tam morp rph hic rock ro cks s wit ith h th thei eirr min ine era rali lize zed d zones had been re rea ached, so th tha at th the e str tre eams of th the e Eoc ocen ene e ran alon along g an and d thr throu ough gh the them m.

Eocene str tre eams. Rid idg ges and vall lle eys foll fo llo owed th the e nor orth th-s -sou outh th tr tre end ndin ing g bed eds s of hard hard an and d so soft ft ro rock ck.. The subt su btro ropi pica call clim cl imat ate e of th the e early early Eoc ocen ene e to toge geth ther er with othe ot herr co cond nditi ition ons s pa parti rticu cula larl rly y favo fa vora rabl ble e to ro rock ck di si sinntregation,, tregation such su ch as a mor more e pr prol olon onge ged d time of stabi stabilit lity y in the the ear arth th's 's cru rust st,, made it possib ible le fo forr th the e gold in the th e su surfa rface ce ro rock cks s to be be relea releas sed fr fro om it its s matr trix ix. The hen n came th the e in ince cep pti tion on of th the e Ter erti tiar ary y Sie ierr rran an uplift, uplif t, whi hich ch re reju juve vena nate ted d stre st ream am flo flow w, ca caus usin ing g th the e re re-leas le ased ed go gold ld in th the e dis isin inte teg gra rate ted d vei ein ns to be be wa wash she ed into in to th the e ri riv ver channels ls,, res re sult ltin ing g in very very ri ric ch concentrati tio ons. The str tre eams were loaded wit ith h fin ine e quart qu artz z sa sand nd an and d pe pebb bbles les,, togeth tog ether er with cla lay ys de deri rive ved d from fr om th the e de deco com mpo pose sed d feld fe ldsp spat athi hic c parts pa rts of the the ro rock cks. s. The fi fin ner part rtic icle les s were washed to the the sea, and as a resu re sult lt the th e Eoce cen ne (lo (l one fo form rmati tio on) toda to day y co con nta tain ins s larg la rge e de depo posi sits ts of com commer erc cia iall cla lay y in inte terb rbed edde ded d wit ith h quart qu artz z sa sand nds. s. The wes westw twar ard d til tiltin ting g an and d res resul ultin ting g ac acce cele lera ratio tion n of  stream stre am flo fl ow in inte terr rrup upte ted d the th e nort rthh-so sout uth h dra rain inag age e syst sy stem em in inhe herit rited ed fro from m th the e Cre reta tace ceou ous s perio pe riod. d. The readju ad just stm men entt of the st stre ream ams re resu sult lte ed in the their gen ener eral al dire di rect ctio ion n of flow flow be bein ing g fin final ally ly ch chan ange ged d fr from om no nort rth h an and d sou so uth tr tre end nds s to a wes este terl rly y cou ours rse, e, so som mewhat as it is tod to day. The lo lon ngest of th the ese known str tre eams even head he aded ed fa farr to the ea east st in into to wha hatt is no now w Nev Nevad ada a. Har ardl dly y ha had d th the e Eoc ocen ene e co com me to a close close whe hen n muc uch h rhyo rh yolit lite e as ash, h, th thro row wn in into to th the e ai airr fro from m vo volc lcan anoe oes, s, setse ttle tl ed ov over er th the e re reg gio ion. n. By Oli Olig goce cen ne ti tim me, rh rhy yol olit ite e as ash h had co cove vere red d much of th the e nort rthe hern rn Si Sier erra ra Neva vad da, dam da mmin ing g ri riv ver ers s and fo form rmin ing g la lak kes es,, the th e bott tto om se sed dimen ents ts of whi which ch ar are e no now w repre represe sent nted ed by thin thinly ly la laye yere red d pip ipe e-c -cla lay y immedia iate tely ly overl rly yin ing g the th e ri ric cher gold ld-bearing grav bearing gravel el.. The ne new wly de deve velo lope ped d riv river ers s, flowing dir irec ectl tly y down th the e west ste ern rn-t -til ilte ted d slo sl ope of th the e Sie ierr rra a, over ov er a vo volc lca ani nic c co cove ver, r, as co cons nse equ quen entt dra rain inag age, e, wer ere e repe re peat ated edly ly in inte terr rrup upte ted d by co cont ntin inue ued d ej ec ectio tions ns of la lava va and a fu furt rth her ti tilt ltin ing g of th the e re reg gio ion n. Not unti till th the e la late te Pli lio oce cen ne or earl early y Ple leis isto toc cen ene e did di d th the e con onst sta ant out ut-pourin pour ing g of lava lava ce cea ase se.. Then en,, by a seri series es of vio viole len nt earth ea rth mov ovem emen ents ts,, the th e Si Sier erra ra Nev evad ada a br brok oke e away fro from m the th e re regi gion on to the the ea east st al alon ong g hu huge ge fa fau ult lt-s -sca carp rps, s, whic ich h are fo form rmed at th the e fo foo ot of th the e pre res sent ste tee ep easte tern rn slo lop pe, where dis isp pla lac cements are now mea measure red d in thousa tho san nds of fe feet et.. Wit ith hin th the e Sie ierr rran an sl slop ope, e, small lle er adju jus stment fau fa ult lts s als lso o bro rok ke th the e conti tin nuit ity y of the the olde ol derr buri ried ed Ter erti tiar ary y st stre ream am gra rad des es.. Some of th the e an an-cie ien nt st stre ream ams, th the e co cour urse ses s of whi which ch hea ead ded fa fart rthe herr to the th e ea east st,, were vi virt rtu ual ally ly 'c 'cho hop ppe ped' d' into in to man any y pie iece ces; s; som so me wer ere e el elev evat ate ed an and d oth ther ers s de dep pre ress sse ed, and ma many were we re warpe warped d to va vario rious us pe pecu culia liarr po posit sition ions. s. Und ndou oubte btedly dly ther th ere e are so som me se segm gmen ents ts of th thes ese e ol old d ch chan anne nels ls whi hich ch now lie deeply buri rie ed beneath gre rea at th thic ick kness of  allu al luv viu ium m in dow down-d -dro ropp pped ed faul fa ultt-b blo lock cks s east ea st of th the e Sierran Sie rran esc escarp arpme ment. nt. I n th the e Gre rea at

Struct Stru ctur ural al co cont ntro roll of th the e dr drai aina nage ge,, fu fully lly de deve velo lope ped d duri rin ng tb tbe e Cre reta tac ceo~s, was th thu us inh inheri rite ted d by the the

Bas asin in an and d th the e Moj ojav ave e Des ese ert re regi gion on of Cali Califo forn rnia ia and an d Neva vada da are re rem mnant nants s of Tert rtia iary ry stre st ream am dep epos osit its, s, inte in terb rbed edd ded wit ith h or lyin lying g ben enea eath th

lavas lav as,, alll of whic al ich h and warp warping. ing.

have

suff su ffer ere ed

muc uch h

by fau fault ltin ing g

In thes these e reg re gio ion ns, however er,, the th e mos ostt im imp por orta tant nt period peri od of pl plac ac;e ;err fo form rmat atio ion n wa wass in th the e ea earl rly y Pl Plei eist stoocene ne,, ra rath ther er th than an in the the Te Tert rtia iary ry.. Two ty typ pes of lo lode de gold su sup ppli lied ed th the e so sou urc rce. e. One ty typ pe was fo form rme ed in muc uch h th the e sa same me man anne nerr ,a ,ass th the e Si Sier erra ra Nev evad ada a lo lode des. s. The Th e ot othe herr co cons nsis iste ted d of mi mine nera rali lize zed d zone zo ness in rh rhyo yoli lite te of ear early ly an and d mi midd ddle le Te Terti rtiar ary y tim time. e. In the the Pl Plei eist stoc ocen ene e ther th ere e we were re no norm rmal al st stre ream amss flo flowi wing ng th thro roug ugh h th the e de dese sert rt,, fed fe d by me melt ltin ing g gl glac acie iers rs of the the hi high gher er mo moun unta tain ins. s. Pl Plaacers ce rs th that at we were re fo form rmed ed by the these se Pl Plei eist stoc ocen ene e stre st ream amss have si sin nce been la larg rge ely co cov vere red d by dese sert rt al allu luv via iall fan fa ns. Some hav have been ele lev vate ted d and an d are cu cutt by mo more rec re cen entt st stre rea ams, when pre prese sen nt in this this ari rid d re reg gio ion n, so that th at re rece cent nt co conc ncen entr trat atio ions ns from fr om ol olde derr ri rive verr gr grav avel elss prov pr ovid ide e on one e so sour urce ce fo forr the the de dese sert rt dr dry y plac placer er.. In the the Kla lama math th Mou ount ntai ains ns,, thou th ough gh th the e ea earl rly y ge geoologic logi c hi hist stor ory y wa wass much much like th that at of the the Si Sier erra ra Ne Neva vada da,, ther th ere e were no lava lavas to fil filll th the e val alle ley ys in whi whic ch th the e stre st ream am gr grav avel elss we were re depo deposi site ted. d. Uplif Up lifts ts,, acco ac comp mpan anie ied d by ren renew ewed ed str tre eam am-c -cu utt ttin ing g, cause sed d terr te rra ace cess to be left le ft on the the vall valley ey si side des, s, wh wher ere e th the e ri rich ch gr grav avel elss ha have ve given give n up thei theirr go gold ld to hyd hydra raul ulic ic mi mini ning ng.. So Som me of th the e fine fi nerr go gold ld part partic icle less were we re washe washed d by th the e river riverss to th the e sea and have sea have fo form rmed ed de depo posi sits ts kn know own n as be beac ach h pl plac acer erss alon al ong g th the e no nort rthe hern rn sh shor ore e of Califo Californ rnia ia.. Down Do wn-f -fau ault ltin ing g of vari variou ouss de degr gree eess of mag magni nitu tude de in places caused accumula lattio ion ns of gravels to fo form rm,, espe es peci cial ally ly on the the down down-t -thr hrow ow si side dess of fau fault lts. s. A nu nummber of such faults are locate ted d in both th the e Sie ierrra Nevada and Klamath Mounta taiins, and may hold a reserve of gold not yet entir ire ely recove red. In th the Sier Si erra ra mos ostt of thes these e min inor or displ displac acem emen ents ts show sh ow th that at the east side of the fault-pla lan ne has been dro dropped down do wn,, so so·· th that at wh wher ere e fa faul ults ts cr cros osss wes estw twar ard d fl flow owin ing g rive ri vers rs,, ac accu cumu mula lati tion onss of grav gravel elss ha have ve ta take ken n pl plac ace e in pock po cket etss th thus us fo form rmed ed,, ea east st of the the faul faultt-pl plan ane e and an d upupstream. The whole Ple leis isto toce cen ne per erio iod d even ev ents ts for for Cali Califo forn rnia ia.. The Th e east easter ern n

was one of gre grea at side si de of the the Sier Sierra ra

Nevada Neva da wa wass ra rais ised ed to ver very y lo lofty fty he heig ight hts. s. Th The e westw westwar arddflow fl owin ing g st stre ream ams, s, as a con conse seq que uenc nce, e, were we re so gre great atly ly acce ac cele lera rate ted d that th at th they ey cu cutt de deep ep an and d ru rugg gged ed ca cany nyon ons. s. The upri risse, acc cco ompanie ied d by fau fault ltin ing g, cause sed d su such ch vio iole len nt eart rth hquake kess tha th at en eno orm rmo ous mass sse es of ro rock  were we re sh shl1 l1ke ken n fro from m the the mo moun unta tain in si side des, s, in many many place placess to form form loca locall la lak kes whic ich h wer ere e la late terr to be dra drain ine ed and an d dest destro roye yed d by ac acti tive ve er eros osio ion. n. Gl Glac acie iers rs de deve velo lope ped d in the hi high gher er mou ount ntai ains ns an and d cr crep eptt do down wn th the e ca cany nyon ons, s, car arv vin ing g them th em wid ide er and le leav avin ing g the th em U-s -sh hap ape ed in form. Their mel rin ing g suppli lie ed much water to the str tre eam ams. s. Some lo loc ca I volc lca anic cone ness were buil iltt up here he re an and d th ther ere e ne near ar or ove overr th the e fa faul ultt pl plan anes es.. The Th e Tert Tertia iary ry st stre ream am grav gravel els, s, wh whic ich h ha had d lo long ng been been buri bu rie ed deep eply ly benea eath th la lav vas, wer ere e expose sed d by th the

Pleist Plei stoc ocen ene e cany ca nyon on-c -cut uttin ting g rive ri vers rs.. Fr From om th the e diss dissec ecte ted d port po rtio ions ns of the the old old ch chan anne nels ls,, gold go ld was re remo move ved d an and d was ashe hed d in into to th the e ne newe werr st stre ream ams, s, whic wh ich h co conc ncen entr trat ated ed it on the their ir be bedr droc ock k ri riff ffle les. s. Th The e re rema main inin ing g po port rtio ions ns of  the th e Te Tert rtia iary ry deposi sits ts were le left ft wit ith h th thei eirr stu tub bs exposed pose d hi high gh up on the the in inte terv rven enin ing g ridg ri dges es.. In pl plac aces es,, ero er osio ion n mere rely ly st stri rip pped the th e coveri rin ng of volc lca ani nic c tuff tu ffs, s, sa san nds and gra rav vels fr fro om the the be bed dro rock ck,, le lea avin ing g the th e chann channel el wi with th its ric rich h go gold ld depos deposits its la laid id pr prac actic tical ally ly bar are e fo forr th the e lu luck cky y ear arly ly min ine er to win win. Some of the the fin fi ner part rtic icle less of gold gold wer ere e sw swep eptt cl cle ear out to the the Grea Gr eatt Val alle ley y wh wher ere e th they ey wer ere e dr drop oppe ped d on the the ed edge ge of  the th e plain plain.. Th Thes ese e ar area eass ar are e no now w the dredg dredge e gr grou ound nds. s.

Ideal cross-section of a r iv iver in t he he Sierra Nevada, the bed of whi which ch ha hass su suff ffer ered ed dow do wnn-fa faul ulti ting ng on th the e up upst stre ream am sid ide, e, ca cau usi sin ng grav avel el s, san and d, and sil iltt to acc accumulat ate e in th the pock po cket et th thus us fo form rmed. ed.

The ge The gene nera rall we west ster ern n ti tilt lt of the the Sierr Sierra a Ne Neva vada da ha hass been be en fo foun und d to cont contin inue ue al alon ong g th the e sa sam me sl slop ope e (a (abo bout ut two tw o degr degree ees) s) fa farr be bene neat ath h th the e al allu luvi vium um an and d se sedi dime ment ntss of the the Grea Greatt Val alle ley. y. Ar Area eass dr dred edge ged d fo forr gold gold va valu lues es in the th e gr grav avel elss th thro rown wn do down wn by the gr grea eatt ca cany nyon on-c -cut uttin ting g riv ri vers of th the e ra ran nge li lie e alo lon ng th the e ex extr trem eme e west ste ern marg ma rgin in of the the fo foot othi hill llss ne near ar th the e pl plac ace e wh wher ere e be bedr droc ock  k  pass pa sses es be bene neat ath h th the e al allu luvi vium um,, an and d al alig igne ned d in a di dire recction ti on N. N.20 20o o W. Th The e gr grav avel elss dr dred edge ged d do not not lie di dire rect ctly ly on bed bedro rock ck bu butt on tuff tuffac aceo eous us cl clay ay la laye yers rs,, spre sp read ad ou outt abov ab ove e th the e detrit detritus us-c -cov over ered ed down do wn-w -war arpe ped d Sier Si erra ran n su surrface fa ce.. Be Bene neat ath h th the e 'f 'fal alse se-b -bed edro rock ck'' and an d cut in th the e true true bedr be droc ock k su surf rfac ace e is a stre stream am pa patte ttern rn wi with th go gold ld-b -bea eari ring ng gra rav vel fi fill lle ed ch cha annel els, s, now re rea ach che ed only in one one or two tw o pl plac aces es.. This Th is bu buri ried ed ch chan anne nell sy syst stem em un undo doub ubt-e t-edl dly y hold ho ldss in rese reserv rve e a grea greatt we weal alth th fo forr fu futu ture re im impr prov oved ed expl ex plor orat atio ion n and an d devel develop opme ment nt.. Exce Ex cess ssiv ive e unde un derg rgro roun und d wate terr is alw lway ayss enco cou unte tere red d in thes these e min ine es whic ich h are ar e lo loca cate ted d be bene neat ath h th the e le leve vell of the the allu alluvi vial al pl plai ain. n. The Th e gr grea eatt di diff ffer eren ence cess betw be twee een n th the e ge geol olog ogy y of the the Coastt Ra Coas Rang nges es an and d th that at of the the Sie ierr rra a an and d Kl Klam amat ath h re re-gion gi onss ar are e fund fundam amen enta tall in that that th the e we west ster ern n ar area ea se serv rved ed freq fr eque uent ntly ly as a basin basin fo forr dep depos osit itio ion n du duri ring ng th the e Tertia Tertiary ry and Cre reta tace ceo ous, whil ile e th the e la latt tte er rep re pre rese sen nte ted d lan la nd are rea as thro th rou ugho hou ut tha th at ti tim me. Th The e Coas astt Ran ang ges to to-geth ge ther er wit ith h th the e Gr Grea eatt Val alle ley y no now w co cont ntai ain n en enor orm mou ouss accu ac cumu mula lati tion onss of mari marine ne Te Tert rtia iary ry and an d Cr Cret etac aceo eous us

sed se dim imen ents ts whi hile le the Sie ierrra Neva vada da and K Kla lam math Mou ount ntai ains ns ar are e not so cover covered ed.. Cr Cret etac aceo eous us an and d Terti Tertiar ary y stre st ream amss cour co ursi sing ng do dow wn th the e mou ount ntai ain n fl flan anks ks br brou ough ghtt grav gr avel el,, sa sand nds, s, an and d clay clayss in into to a mar argi gina nall se sea. a. The Th e ve very ry fa fact ct th that at st stre ream amss ar are e co conv nvey eyor orss of mat mateerials, rial s, in con contr tras astt to the the basin basinss of dep depos osit itio ion n tow to war ard d whi hich ch th they ey fl flow ow,, ac acco coun unts ts fo forr the the ve very ry di diff ffer eren entt ge geoologi lo gic c co cond ndit itio ions ns on the the tw two o si side dess of the the Gr Grea eatt Va Vall lley ey.. Cer erta tain in ge geol olog ogic ic tim ti me di divi visi sion onss of th the e Cre reta tace ceou ouss and an d Tert Tertia iary ry of the the Coas Coastt Ra Rang nges es ar are e re repr pres esen ente ted d by stra st rata ta mea easu sure red d in man many y th thou ousa sand ndss of fee feet, t, whi hile le in the th e Sierr Sierra a me mere re fi film lmss of Ter Terti tiar ary y gr grav avel els, s, or de depo posi sits ts of no greater thickness than a few hundred feet, tra tr app pped ed by volc lca ani nic c cove co veri rin ngs gs,, rep eprres ese ent som so me of  thes th ese e sa sam me la latter per erio iod ds. Par arti ticl cle es of go gold ld,, rec recurrent re ntly ly wa wash shed ed f ro rom m th the e mi mine nera rali lize zed d rock ro ckss of the mo moun un-tain ta in ra rang nge e wer ere e dr drop oppe ped d by rea reaso son n of thei theirr hi high gh sp speecifi ci fic c grav avir iry y, and reta taiined in the bed edrroc ock k rif ifffle less of  both bo th th the e an anci cien entt an and d moder modern n st stre ream ams, s, wh whil ile e th the e light lighter er detr de triitu tuss was car arrrie ied d to the the br bro oad se sea a bas asin inss to fo forrm stra st rata ta co cove veri ring ng hu hund ndre reds ds of sq squa uare re mil iles es..

The dep eple leti tion on of the mor ore e ac acce cess ssib ible le and an d mor more e easily easi ly di disc scov over ered ed gold go ld plac placer ers, s, foll fo llow owed ed by lo loss sses es due du e to poo poorl rly y di dire rect cted ed ex expl plor orat atio ion, n, call ca llss fo forr a mor more e effe ef fect ctiv ive e te tech chni niqu que e to br brin ing g fu furt rthe herr su succ cces esss to pl plac acer er min inin ing. g. The te tech chni niq que is av avai aila labl ble; e; the th e next next th thin ing g to do is is to ap appl ply y it it.. First, there is aerial photography which may spee sp eedi dily ly an and d accur accurat atel ely y give gi ve a wea wealt lth h of va valu luab able le in in-for orm mat atio ion n as reg egar ard ds geol ge olog ogy y, and an d in addi additi tion on,, the th e finest sort of a map showing surface features in great gr eatest est det detail ail.. Sec econ ond, d, the here re is ge geop oph hys ysiica call surrvey su eyin ing g whi hich ch,, whe hen n co coor ordi dina nate ted d with wi th ge geol olog ogy, y, may grea greatl tly y ai aid d un un-derg de rgro roun und d pr pros ospe pect ctin ing g in ma maki king ng new disc discov over erie iess and an d in redu reduci cing ng it itss co cost st by mor more e in inte tell llig igen entl tly y dire di rect ctin ing g itss co it cour urse se of acti action on.. Thir Th ird, d, ph phys ysio iogr grap aphi hic c geol ge olog ogy, y, ad adva vanc nced ed to a mor more e system syst emat atic ic scie sc ienc nce e than th an ev ever er befor before, e, may be be used used in unra rave vell llin ing g the th e his isttor ory y of the an anci cie ent stre st ream amss and thei th eirr co corr rres espo pond ndin ing g topo to pogr grap aphy hy.. Cont Co ntou ouri ring ng th the e preprelav la va su surrfac ace e is fo fou und to be an ex exce cellle lent nt met etho hod d of  sho sh owin ing g grap aphi hica call lly y this th is an anci cie ent top opo ogr grap aph hy, and an d especially the old valleys in which lay the early gold-b gol d-bear earing ing str stream eamss. Four Fo urth th,, a bet bette terr un unde ders rsta tand ndin ing g of des deser ertt pr proc oces esse sess in gen ener era al and an d de dese serrt pla lac cer erss in par partic icul ular ar sho sh oul uld d hel elp p to dev evel elop op a gold gold res ese erve whic ich h ha hass so far far not not rece re ceiv ived ed th the e at atte tent ntio ion n it dese deserv rves es.. Fift Fi fth, h, th the e te tech chni niq que re rece cent ntly ly de deve velo lope ped d In th the e ex ex-aminat amin atio ion n of stra strati tifi fied ed sedi se dim men ents ts,, thei th eirr st stru ruct ctur ure, e, text te xtur ure, e, mi mine nera rall-gr grai ain n comp co mpos osit itio ion, n, etc. et c.,, may be be apt aptly ly

app ppli lied ed to pl plac ace ers rs,, to ai aid in tra traci cin ng ou outt the heir ir OrIgIn and th the e co cour urse sess of the the olde olderr dr dra ain inag age e syst sy stem emss now extinct. In tak takin ing g st stoc ock k of the the poss possib ible le re rese serv rves es of pl plac acer er gold go ld in Cali Califo forn rnia ia,, seve se vera rall so sour urce cess wou ould ld se seem em wor orth th invest inv estiga igatin ting. g. Alll of the Al these se re requ quire ire det detail ailed ed exp explor lorati ation on pri rior or to an any y at atte tem mpt at mini ning ng.. For the most par art, t, thes th ese e re rese serv rves es ar are e bu buri ried ed or con conce ceal aled ed in such such a way way that th at th they ey ha have ve ei eith ther er be been en ov over erlo look oked ed or cons consid ider ered ed too to o re rem mot ote e or too too muc uch h of a sp spec ecul ulat atio ion n forr a mini fo mining ng vent ve ntur ure. e. Su Such ch fac facto tors rs as invo involv lved ed wa wate terr-ri righ ghts ts,, liti li tiga ga-tion ti on,, di diff ffic icul ulry ry in gai gaini ning ng ti titl tle, e, la laws ws un unfa favo vora rabl bly y af-af fect fe ctin ing g hy hydr drau auli lic c min inin ing, g, la lack ck of suffi suffici cien entt capi ca pita tal, l, and an d man any y ot othe herr st stum umbl blin ing g bl bloc ocks ks no now w pr prev even entt go good od placer pla cer gro ground und fr from om bei being ng wo work rked. ed. The po poss ssib iblle rese serrve vess dis isc cus usse sed d in this this repo reporrt may ma y be sum summa mariz rized ed as fo follo llows ws:: Plei Pl eist stoc ocen ene e

and  an d  Recent

Placers.

1. Dee eep p ri rive verr gr grav avel el de depo posi sits ts,, over ov er whi hich ch th the e pr pres esen entt large larg er riv ri vers are no now w flo low wing ng.. Recent and Ple leis isto toc cene faulting caused gravel to be accumulated on the downthr hro ow sid ide e of faul faultts, whi hille th the e ri rive vers rs hav ave e cont ntin inu ued to flow fl ow ov over er th the e gr grav avel elss wit itho hout ut was ashi hing ng th them em co com mpl plet etel ely y out. 2. Pl Plei eist stoc ocen ene e stre st ream am pl plac acer ers, s, buri bu ried ed be bene neat ath h al allu luvi vial al fans fa ns of the the Gre reat at Ba Basi sin n an and d Moj ojav ave e De Dese sert rt.. 3. Recent eph phe emera rall str tre eam dep epo osit itss and allu alluv via iall fans or 'bajada placers' of the Great Basin and M oj ojave Dese De sert rt reg region ions. s. 4. Marine or beach placers along the coast, for th the most mo st pa part rt lo loca cate ted d in nor north ther ern n Ca Cali lifo forn rnia ia.. 5. Isolated high terraces or b en ench gravels, such as thos th ose e wh whic ich h oc occu curr in the the Kl Klam amat ath h Mo Moun unta tain ins. s. Terti Te rtiar ary y

Stre St ream am

Plac Pl acer ers s

6. Gol old d-b -bea eari rin ng chan ann nel elss cut in bed edro rock ck whic ich h li lie e beneat ath h the fa fals lse e bedr droc ock k laye la yers rs of th the e dre redg dge ed are rea as alo long ng the th e we west ster ern n foot fo ot of th the e Si Sier erra ra Ne Neva vada da.. 7. Buri rie ed Tert rtia iary ry cha ch ann nne els and as asssoci ciat ated ed cove vere red d benc be nche hess loca lo cate ted d in the the well well-k -kno now wn gold go ld-b -bea eari ring ng dist di stri rict ctss of th the e sta tate te.. Larg rge e ar are eas sti II li lie e buri rie ed and un une exp xplo lore red d in some so me of the ol olde derr mi mini ning ng di dist stri rict cts. s. 8. Bur urie ied d Tert rtiiar ary y cha ch ann nne els and benc bench hes in th the e la lava va-cove co vere red d di dist stri rict ct whi hich ch li lies es be betw twee een n the th e Si Sier erra ra Nev evad ada a an and d Klamath Mountains. Most of this area is probably too, deep de eply ly co cove vere red d to be rea reach ched ed by min minin ing, g, bu butt th the e so sout uthe herr rr margi ma rginal nal are area a ma may y have have so some me po possi ssibil biliti ities es.. 9. Ter erttia iary ry cha han nne nels ls of th the e Gre rea at Basi sin n and Moja Mojav ve Des ese ert are reas as,, int nte erb rbe edd dde ed wit ith h vo volc lca ani nic c rock ro ckss or lyi lyin ng bene be neat ath h them th em.. 10.. Te 10 Tert rtia iary ry mar arin ine e pl plac acer ers. s. Fin inel ely y di divi vide ded d gold go ld part partiicles in the lone formation at the point where the correspon sp ondi ding ng Eo Eoce cene ne st stre ream amss en ente tere red d th the e lo lone ne se sea. a. Cretaceous

Marine Ma rine

Placer Pla cers. s.

11.. Cre 11 reta tace ceo ous mari rin ne pla lac cer erss, larrge la gely ly in th the Chic ico o conglo cong lom mer erat ate e (Upp (U pper er Cr Cret etac aceo eous us)) beds be ds of no nort rthe hern rn Cali Ca li-forn fo rnia ia.. The Lower Cre reta tac ceou ouss beds ar are e als lso o re rep por ortted to cont co ntai ain n so some me gold gold-b -bea eari ring ng laye la yers rs.. Larg arges estt

Reser Re serve ve..

The larg larges estt of the these po posssib ible le resserv re rve es the remai the remaini ning ng buri buried ed Te Tert rtia iary ry st stre ream am pl plac acer erss Sierra Sier ra Nev Nevada. ada.

pro roba bab bly lie li e in of th the e north norther ern n