Contents
Animal Who's Who Animal Homes Feeding Time Resting Time When Winter Comes Animal Babies Plants That Make Seeds Trees Through the Year Plants Without Seeds Flowers How Seeds Travel Why the Wind Blows What Makes It Rain? Snow and Ice Rainbow Colors Light and Shadow The Big Round World Day and Night How Rocks Were Made What Is Inside t a h? , , Pebbles Sand and Soil Land and Sea 0
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A GOLDEN
EXPLORING EARTH BOOK
Animals, plants, rocks, gravity, day and night, rain and snow, the sky and the ocean-with many fascinating experiments and activities
By Rose Wyler Illustrations by Marjorie Hartwell and Valerie Swenson Cover by Rod Ruth
�
•
GOLDEN PRESS
Western Publishing Company, Inc.
Racine, Wisconsin
Copyright© 1973, 1957 by Western Publishing Company, Inc. All rights reserved, including the right of reproduction in whole or in part in any form. Printed in U.S.A. GOLDEN PRESS@, GOLDEN, and A GOLDEN EXPLORING EARTH BOOK are trademarks of Western Publishing Company, Inc.
ANIMAL
WHO' S WHO
How MANY kinds of animals do you
. snakes and toads and frogs and turtles
know? You can name more than you
have bones. But there are many animals
think. You can list many big animals of
which have no bones .
the farm and woods and the zoo . You
Worms have none. Neither do the
know the tallest animal, the giraffe.
insects, spiders, and thousand-leggers.
And the biggest animal, the whale.
Animals
But remember-there are tiny ani
that
live in shells--clams,
oysters, and snails-have no bones.
mals, too. You may not think of an ant
Then there are animals with hard,
as an animal. But it is one. It is called
tough skins-the crabs and lobsters .
an insect. All insects have six legs, and
They have no bones. And jellyfish and
that is how many an ant has. Count
starfish have none either .
them and see.
The smallest animals of all have no
Is a spider an insect? Count its legs.
bones . They can be seen only through
You will find it has eight. A spider is
a magnifying glass or a microscope.
not an insect. Neither is a thousand
These smallest animals have no faces,
legger. But both are animals .
no arms, no legs. They have no shells,
Some animals have no legs at all. Worms and snails are legless animals . So are fish and snakes.
no feathers, no fur, no skin. They are like tiny drops of jelly. Why are they all called animals?
Some animals have bones. Some do
All animals are alike in some ways.
not; You can think of many animals
They all breathe. They all eat. And
with bones . All the fur-bearing ani
they all have young that grow up to be
mals, all the birds and fish, all· the
like their parents.
ANIMAL HOMES A WILD animal's home is the place where it feeds and rests. This may be a field of grass or a patch of dirt under neath a big stone. It may be a pond or a desert, a hot jungle or the frozen northland. The animals that live in cold places have thick coats of fur or fluffy feath ers that keep them warm. In deserts, many animals have scaly skins which protect them from dryness. Most sea shore animals have shells which keep their bodies moist when the tide goes out.
In a field.
In the desert.
This field mouse lives among the tall grasses.
Here an owl lives in a cactus, a snake under
a rock, and prairie dogs in a burrow.
At the pond. Chipmunks have tunn eled among the tree roots, and a bird has nested on a branch. Fish and snails are at home near the bottom of the pond. The frog and
d
the turtle spen -time both in and out of the water. The dragonfly spends much of its time in the air.
Many animals spend some time in shelters. There they hide or rest or raise their young. Bears, coyotes, bobcats, and mountain lions use ready-made shel ters. These may be caves or tree hollows. Some animals, such as prairie dogs and ground squirrels, dig underground burrows. These may have several doors and rooms connected by t,unnels. The home of many spiders is a web. This web acts as a net to catch insects, which the spider eats. A clever digger.
The trapdoor spider lives in a silk-lined
room with a door that fits exactly.
Winter homes.
The bear sleeps in the tree, but the deer
and the wolf stay awake an d hunt food. a store of nuts in the tree.
Along the beach.
Here (left to right) are a turtle, fish,
shellfish, a starfish, and a crab-all at home along the sea shore.
Above fly their neighbors, the gulls.
The squirrel has
Nibblers. Squirrels, chipmunks, and field mice eat all day.
Big eaters. mals.
Mountain lions and coyotes hunt other ani
When they catch one, they eat all they can hold.
Days may pass before they eat again.
FEEDING
TIME
WILD ANIMALS do not eat three meals
like to eat both plant and animal food.
a day . Birds and many small furry ani
Some, such as the mountain lion, eat
mals, such as squirrels, feed nearly all
only meat. They have sharp teeth and
day long. Other animals, such as moun
claws for tearing their food.
tain lions and coyotes, eat only once in a while. Some animals, such as snakes, do not get hungry often. They eat about once
Others eat only plants. Deer and sheep could not easily eat raw meat if they tried. They have flat teeth that are good for grinding plants.
a week in warm weather, and in cold
Birds have no teeth at all. They
weather even less. They feed on in
swallow their food whole. Insects, too,
sects, worms, frogs, and mice.
get along without teeth.
No animal eats as many kinds of
Every animal must eat. And every
food as you do. Few types of animals
animal has some way of getting food. O nce-a-week eater. a snake's hunger for a
A mouse may be enough to satisfy
Mountain lion
Teeth
and claws.
Above
you
see
the
skull, head, and foot of a mountain lion. These show the teeth ar\d claws which this
animal uses to tear its food.
The same
parts of a deer's body (below) show that
this gentle animal is a vegetable eater, not
a hunter.
llnl WUs. lirdt with thick, short .,. are expert at pfddng seeds off plants. The duck's broad, ftat bill Is handy for scooping up weeds and Insects from the water. The long sharp biDs help
some
birds to catch Insects In the air.
Sucldng straw.
is a long tube.
of grasshoppers, bite off a piece of a leaf or stem.
hard
little jaws
of a butterfly this the Insect
The mouth Through
sucb nectar from flowers.
Mou ..
Cat
Ey..
That Stay Open
Fish
Insect
RESTING TIME FINDING FOOD is the main job of most
tom. Others rest in the water, moving
animals. When they are not eating,
their fins slightly to keep themselves
they rest.
steady. They do not even close their
Some animals, like people, sleep at night and eat during the day. Others do
eyes. They cannot, because they have no eyelids.
just the opposite. They rest during the
Many animals do not sleep. They just
day in a cool, dark place. At night they
rest without shutting their eyes. In fact,
go out for food. Field mice, kangaroo
only animals with fur have eyelids like
rats, and other small animals feel safer
yours. Birds, frogs, and turtles have a
in the dark.
third eyelid that is thin and transparent.
In the deep water there is little change from day to night. In the ocean' s depths,
These lids protect the eyes but do not keep out light.
it is always dark. The fish and other sea
Most animals lie down to rest if they
animals that live here do not have night
can. But birds can' t lie down. Most birds
and day. They just eat for a while, then
perch on branches of trees. They fluff
rest, and then eat again.
out their feathers. They tuck down
When fish rest, some go to the bot8
their heads. And they rest very well.
WHEN WINTER COMES W HEN
WINTER
c o m e s , p la n t s stop
growing. Most trees drop their leaves. Many flowers and grasses die, but their seeds �re under the leaves or snow. Animals, too, get ready for winter. In the fall, squirrels and chipmunks hide nuts to eat during the winter. Field mice store seeds. When deer can no longer find leaves, they will eat the bark and twigs of trees. Many animals do not hunt food in winter. They crawl into underground burrows, caves, or hollow tree trunks for their winter sleep. Insects may sleep in cracks in logs or rocks. Fish and some other water animals swim around all winter. Only the top of the water turns to ice. Under the ice, life goes on. In spring the ice melts. The frozen earth thaws. New plants grow from the hidden seeds. Trees send out new buds and leaves. Animals come out of their winter sleep, and, once again, they can find plenty of food. Winter homes. Deer search for food in the snow-covered
woods. Wh ile the bear sleeps in h is cave, the field mouse scam pers into a hole in a log. The beaver swims to the u nderwater entrance of h is lodge in the pond. The fish keep active near the bottom. Turtles a nd frogs, deep i n the mud, a r e in their winter sleep.
Baby grasshopper hatches from egg.
Mother gra.sshopper lays eggs.
ANIMAL
Young grasshopper and adult look for food.
BABIES
MANY ANIMAL babies grow up without
that shift for themselves. These ani
a mother's loving care. Many of them
mals, like fish, lay jelly-covered eggs
never even see their mothers.
on water plants. Then they leave them.
This is true of insects. If a baby
If you keep snails in an aquarium, you
grasshopper met its mother in a field,
will surely see their eggs. They look
it would not know her. In the fall, a
like dark dots in a drop of clear jelly.
mother grasshopper lays her eggs in a
In the spring, you may find some
tiny hole in the ground or in soft wood.
frogs' eggs near the edge of a quiet
Then off she goes.
pond. The eggs are ball shaped and -
·Months later, when the weather
covered with colorless jelly. Tiny tad
turns warm, the eggs hatch. The young
poles hatch from them. They look and
grasshoppers that come from the eggs
live like fish for a while.
can take care of themselves. They can
Eggs of land animals-mainly birds
jump around and get their own food.
and turtles-are covered with tough
They need no help.
skin or shell. This covering keeps the
Nearly all water animals have young Eggs of water animals.
inside of the eggs moist.
Under the goldfish (lower left) are some fish eggs. At center are some frogs
eggs. Notice the four stages that a frog goes through before it grows up. The snails (at right) also lay eggs.
Eggs a re laid by the mother bird in a
The mother sits on the eggs to keep them
Before leaving home, the
carefully built nest.
warm until they hatch.
must learn to perch, fly, and g et food.
baby bird
The mother turtle covers her round
Almost all fur-bearing animals do not
white eggs with leaves or dirt. Then
lay eggs. The mothers give birth to ba
W hen the young
bies and feed them milk. These babies
hatch, they waddle off to hunt for food.
get a lot of care and training. You may
Animals that do not take care of
have watched a mother cat with her
she leaves them.
their babies usually have a great many.
kittens or a dog with her puppies.
Fish lay hundreds of eggs, but most of
Just think how much care human
these or the little fish that hatch from
mothers must give their babies. They
eggs are eaten by other animals.
feed their babies and keep them warm
Birds lay their eggs in a nest and sit
and safe. Human mothers also train
on them. They keep the eggs warm
their babies for many years. That is
until they hatch. Then the parents feed
because human babies have so much to
the babies and teach them to fly.
learn!
EXPERIMENT
RAISE TADPOLES Find some frogs' eggs. Put them in a big glass jar or tank filled with water and plants from a pond. When the eggs hatch into tad poles, watch them care for themselves and grow!
II
Seeds of many kinds. An oak tree's seeds are acorns. An apple tree's seeds are in the core of the apple.
PLANTS
The seeds of grasses are very small, and you may need a magnifter to get a good look at them.
THAT MAKE SEEDS
THE PLANTS you know best have big,
not so big. Bite into the core of
bright flowers. You know many plants
apple and you will find some.
with small, dull flowers, too. Perhaps you never noticed their blossoms.
an
In each of these seeds, there is a baby plant. There also is food for it.
Grasses have flowers. They are tiny
Pine and fir trees make seeds, too.
and green. Most trees have flowers,
But they do not bloom. They make
too. You know apple blossoms and the
their seeds in cones. So they are called
flowers of other fruit trees. But do you
cone-bearing plants. The other kinds of
know the flowers of the oak? They are
plants that make seeds are called flow
small and green. They bloom in the
ering plants.
sprmg.
Both
-
cone-bearing
and
flowering
Little flowers as well as big flowers
plants have roots, stems, and leaves.
make seeds. Grass seeds are as small as
The root anchors the plant. It also
dust specks. Oak seeds are much big
takes in water and other needed things
ger. You have seen them many times
from the soil. The stem connects the
you call them acorns. Apple seeds are
root and leaves.
12
CONE-BEARING PLANT
FLOWERING PLANT
Air enters through
tiny holes
Leaves are like kitchens. Tiny pipes
sunlight, it turns air and water into a
in the stem bring the leaf water. In
sugary mixture. This is the plant's food.
stead of windows, tiny holes let in air
Leaves use some of the food they
and sunlight. The air is mixed with
make. The rest goes through veins into
water and other materials. The green
the stem. The stem uses some of the
coloring in the leaves-chlorophyll
food. All that is left goes to the roots.
acts as the cook. With the help of
They use some and store the rest.
EXPERIMENT
WATcH SEEDs FoRM Pick different kinds of flowers and put them in water. In each flower, find the place where the seeds are formed. LOOK INSIDE THE SEEDS Take some fairly big seeds and soak them overnight. Try beans, peas, and corn. Cut them in half and see the baby plant inside. LOOK AT A LEAF WITH A MAGNIFYING GLASS Try to find the tiny holes through which the leaf breathes. Look on the underside of the leaf for them. See how the leaf veins connect.
13
TREES THROUGH THE YEAR HAVE YOU ever tried to climb the stem
The bark p r o t e c t s t h e tru n k ,
of a tree? Of course you have. For a
branches, and twigs. Between the bark
tree's stem is its trunk.
and the wood is a green layer. Small
Trees are like other plants that grow
tubes ru n through it. These tubes carry
from seeds. They have roots, stems,
down to the root the food made by the
and leaves. But they are. different in
leaves. The food that is not used by the
that they may live for many years. No
root is stored. Other small tubes run
other plants are as hardy as trees.
through the wood and carry water from
Each of the main parts of a tree has some way of living through
the root to the leaves.
summer
Evergreen trees, such as pine and
heat and winter cold. The upper sec
spruce, have leaves shaped like needles.
tion of the root has a tough skin that
These are covered with an oily skin
keeps it from freezing or drying out.
which keeps them from freezing or
The root tips reach deep into the
drying. Crush some and they feel oily.
ground. There the soil does not freeze,
Notice their nice smell. That comes
and there they can find water all year.
from their oil.
ftowers
A MAPLE TREE
leaf
winged seeds
L�ln
Leaf In
Leaf In autumn, to fall
Other kinds of trees prepare for winter by shedding their leaves. Late in
summer,
the bottom of each leaf
stem begins to harden. Less and less water passes from the twig into the leaf. The leaf begins to lose its green color. While the leaves are drying, they tum yellow, red, purple, and brown.
Soon after these beautiful colors ap pear, winds tear the withered leaves from their twigs. Strong gusts blow them away.
Holly
Tulip
(tree) 15
•
Its buds ready, an apple tree waits for spring.
New leaves will be•ready to take the place of the old ones. They are hidden in buds, covered with thick coats. The buds were made in the
summer.
When spring comes, sap rises from the roots. It goes into the buds. They swell and grow. Suddenly they open. ·
Out come the new leaves.
Flowers come from. the buds too. Soon seeds start to form. But they ripen slowly. Many kinds fall to the ground in au tumn and lie there through the winter. When spring comes, they sprout. Some seeds do not get far from their parent trees. They become seedlings th�t live for just a few years. They die because they cannot get enough
sun
light. Other seedlings grow and grow. They live for many, many years and become great, beautiful trees. In
late
apples
summer are
leaves drop.
16
and
picked
fall,
the
and
the
EXPERIMENT
GRow YouR O wN TREES You can plant tree seedlings in flower pots and watch them grow. Spring is a good time to do this. In the fall you can plant grapefruit o r orange seeds i n a little flower pot. You will soon have seedlings of your own.
EXPERIMENTS
LEAF CoLLECTING Summer is the time to start a leaf collec tion. Place your leaves between sheets of newspaper. Pile heavy books on top of the sheets, to keep the leaves flat. When the leaves are dry, mount them on stiff paper.
TwiG CoLLECTING In autumn and winter, you can collect twigs. Look for scars along the sides of the twigs. They mark the places where leaves grew. The skin coveri ng the scars formed in the fall. It stopped water from reaching the leaves. Look for buds on twigs, too. They are at the tips and near the scars. In early spring, bring the twigs of differ ent trees indoors and keep them in water, in a warm place. Then watch the buds open. You will have many surprises.
17
PLANTS
WITHOUT
SEEDS
HAVE YOU ever seen some brown pow der on the underside of a fern leaf? Specks of this powder can start new plants. Each speck is a spore. There is no food in it-just the beginning of a new plant. Although ferns never make seeds, they are like flowering plants in many ways. They have roots, stems, and leaves. Some grow so tall they are called tree ferns.
Young ferns
Mosses grow from spores, too. But they have no roots. Instead they have tiny hairs which hold them in place. A little stalk serves as the stem. From it grow leaflets and tiny cases which hold the spores. Horsetail has spore case on sepa rate sta lk.
Seaweeds and pond scum belong in another group of plants that start from spores. These plants are called algae. They have no roots, stems, or leaves. Yet they can make food from air and water, for they have chlorophyll. Pond scums a re common kinds of a l g a e.
Some plants have no chlorophyll. So they cannot make food. They live on dead things--rotten wood, dried leaves, decaying fruit. These are fungus plants.
Each plant starts from a little spore. A mushroom is a big fungus. Molds are fungus plants, too. They dead plants and other wastes.
use
up
EXPERIMENTS
M AKE A SPORE PRINT Use a mushroom for this. First spread a thin coat of a glue and water mixture on a piece of cardboard. Remove the stem of the mushroom. Prop up the cap with toothpicks and set it on the cardboard. Cover the cap with a glass dish. Let it stand overnight. M illions of spores will fall and leave their prints on the sticky paper. GRow BREAD MoLD Set a piece of fresh bread on some alumi num foil. Let it stay in the open air for an hour. Some mold spores will fall on it. Then cover the bread and loo k at it every day. Soon one or more molds will be growing on It. MAKE A Moss G ARDEN Cover the bottom of a big glass jar with some sand. Then put moss and the soil in which it is growing on top. Plant several mosses in the garden. Moisten the soil. Cover the top of the jar with a piece of glass or foil. This will keep it from drying.
19
FLOWERS MorninSHIIory
BRIGHT-COLORED petals are the most beautiful parts of the flower. But the most useful and interesting parts are those that make seeds. The colored petals attract bees and other insects. The insects come to sip the sweet juice, called nectar. This is at the center of the flower. As insects come and go from flower to flower, they help make the seeds. Look inside a tulip or poppy flower. In the center there are many thin stalks with little cases at their tips. These cases hold a powder called pollen. Insects taking nectar
PARTS OF A FLOWER
I
petal
ripening fruit
20
At the center of the petals is a small
Some plants have two kinds of flow
green case with a sticky top. Within the
ers. One has pollen. The other has the
tiny green case are unripe seeds. Before
seed case. Nearly all of these plants
they grow, the seeds must be touched
depend on the wind to carry pollen to
by pollen grains from the same kind
the seed case. They do not have big,
of flower.
bright petals. After all, they do not
That is where insects help. As the
need to attract insects.
insect goes after the sweet juice, the
When pollen reaches the seed case,
powdery pollen sticks to its legs and
the seeds begin to ripen. Then the work
body. On goes the . bee to another
of the petals is done. The petals dry
flower. And there some pollen from
and drop off. But the seeds grow bigger
the first blossom rubs off onto the
in their seed case. You have seen the small seed pods of
sticky, green seed case. Insect visitors may stop at more than
some flowers. But do you know what
one kind of flower. So they often carry
the seed case of the apple flower looks
pollen from different kinds of flowers.
like? It is the whole apple. The seed
But only poppy pollen can ripen the
pod of the oak flower is the acorn
seeds in the poppy seed case. Only
shell. The nut inside is the seed.
tulip pollen can ripen the seeds in the
Inside every seed pod are seed� from which new plants can grow.
tulip seed case.
Apple seeds form in the center of a large fleshy fruit.
The nut meat in a walnut pod is stored The shell of an acorn is a seed case.
The nut inside is a seed.
food . It is used by the seed for growth.
HOW SEEDS TRAVEL SEEDS must be scattered. If they all Poppy seed case
just fell to the ground near the parent plant, there would be no room for them to grow. The poppy has a seed case that works like a salt shaker. It has many little holes under its cap. As the case sways in the wind, seeds are shaken out and blown away. The tulip seed case splits open. Then the seeds pop out. Many small seeds are scattered by
Tulip seed case
the wind. Grass seeds are so light that just a gentle breeze can lift and carry them a long way. Some heavier seeds are also spread by the wind. Milkweed and dandelion have tiny parachutes of fluff that keep them in the air for a while. Others sail through the air on wings. Maple, elm, and ash tree seeds do this.
Milkweed seeds ore like parachutes.
Many seeds ore carried off by birds.
Nuts ore carried away by squirrels.
But many of the heavier seeds are
Birds and other creatures that nibble
carried around by animals or people.
at fruits and berries help in scattering
Some have tiny hooks or burs which
their seeds. The seeds of water plants must be
stick to fur, feathers, and clothing. Nuts are carried away by squirrels or
chipmunks
who often b ury them
scattered too. Those of water lilies are b:uilt like little boats. They float away from their parents to find new homes.
and then forget about them. "EXPERIMENTS
CoLLECilNG SEEDS Look for seed pods in the summer and fall. Keep the seed pods in small bags or cel lophane envelopes. Otherwise the pod may pop open and you may lose the seeds. For a display, mount the seeds on card board. Cover them with cellophane. Then tape down the cellophane.
SPROUTING SEEDS
water. After the water has been soaked up, tum the glass upside down. Seedling stems will twist to reach up. Roots will reach down.
23
WHY
THE
WIND
BLOWS
TAKE a clean glass from the cupboard
But you cannot see air, because it is
shelf. Is it empty? It looks empty. You
made of tiny, tiny, colorless particles.
cannot see anything in it. But it is
The particles are not all alike. They
really full-full of air.
are bits of different gases. You know
Air is all around you. It is pressing
the name of one of these gases-oxy
on you right this minute. The reason
gen. We must breathe oxygen to keep
why you do not feel this pressure is
alive.
that air is inside you as well as outside.
Another gas in the air is water in the
The pressing from the outside balances
form of particles too small to see.
the pressing from the inside.
They are called water vapor. Hang
But there are times when you do feel
up some wet clothes and they dry. The
the air. W hen air moves gently against
water turns to water vapor and spreads
you, you feel a breeze. W hen it moves
through the air. It evaporates.
more strongly, you feel a wind.
When air moves from one place to
You can put air into things such as
another, there is a wind. Blow on
a balloon or a tire. You can let it out.
your hand, wave your arm, or turn on
24
a fan. As the air moves past you, you
than others. At a beach on a warm,
feel a small wind-a breeze.
sunny
day, the sand heats up. But the
You can also make air move if you
water stays cool. The sand acts like a
use heat. When air is heated, the par
stove, heating the air above it. Up goes
ticles move faster. They spread farther
this air, whil� cool air from over the
apart. And this makes the air thinner.
water moves in to take its place . And
The thin, warm air becomes lighter
this is what makes a wind start.
than cooler air around it. Up, up it goes, floating above the thick, cold air.
The warm air particles lose speed as they climb.
They draw closer to
The warm air above a hot stove or
gether, so the air becomes heavier.
radiator always rises. Then, as it cools
Down it goes, taking the place of
off, it comes down. The particles draw
cool air moving toward the beach.
together and the air becomes thicker.
But the hot sand heats the air again.
But how do winds start outdoors?
It rises. Up, down, and up it goes, over
Heat from the The
sun
sun
starts them.
warms some places more
and over again. And so the wind keeps on blowing. 25
EXPERIMENTS
A PINWHEEL Use square of fairly strong paper, 5 inch es each side. Mark as in picture. Cut along lines nearly to center. Without creasing paper, tum in to center the points which have dots. Run pin through center.
' �.... ---.. l6J lA!
Blow up a paper bag. Then hit it. Pop! The crowded air particles rush to spread out. They make the sound by hitting the air und the bag. 1f you want a louder noise, blow up a big balloon md tie the neck. Then stick a pin . . a.... .. r mto lt.�.
....�"""" .. "
•.,...�....•...,. t�
AN AIRPLANE 1. Get a piece of pa
per about 10 inches by 6 inches. Fold it the long way down the middle. 2. At one end, tum each comer outward. 3. Fold again on each side. 4. Fold once more on �ch side.
SEE WARM Am RisE Take a thin, soft paper napkin. Cut a strip about one inch wide and three inches long. Fringe one end. Stick the point of a
CoLD AIR MovEs, Too Place the little flag on the floor in front of the refrigerator door. When you open
pencil through the other end. Now you have
the door, cold air pours out. See how the
a little flag. Hold it over a hot toaster. Ris
flag flutters.
ing warm air pushes up the flag and makes it flutter. Set the flag near the bottom of the toaster and it stops fluttering.
.. •
t
t
t
t t
The rain. The water turns to vapor and rises to the sky, as the arrows show. Then the vapor becomes drops of cool rain.
WHAT MAKES IT RAIN? STRANGE though it may seem, the sun
On a warm day, air often rises. While
makes it rain. Water must first go up
rising, it cools. Its water vapor turns into
into the air before it can come down.
droplets. Puff y little clouds form. More
And it is warmth from the sun that
and more air rises and cools. The clouds
lifts water.
grow. Soon they cover the sky.
The sun shines on the oceans, on lakes,
The drops of water in the clouds grow
and on rivers. Water vapor forms and
bigger, too. When they are too big to
spreads through the air.
float in the air, down comes the rain. The
Warm air can hold a great deal of
big drops splash against the ground.
water vapor, but cold air cannot hold
The rain cools the air, and the air
so much. When warm, moist air cools,
stops rising. No more water vapor comes
some of its water vapor turns to liquid.
to the clouds, so they stop growing, and
Little droplets form and make clouds.
soon the storm is over. The sun comes
If the clouds are chilled, then rain may
out again and begins once more to warm
fall from them.
the air.
28
EXPERIMENTS
MAKE A LITTLE RAINSTORM Heat some water in an open pot. The water turns to gas and spreads through the warm air above the pot. When the warm air rises and cools, a cloud forms. Catch the cloud in a clean glass jar. Drops of water from the cloud settle on the cold glass. They run into each other and make bigger drops. Soon they drip down the jar like rain. PULL WATER FROM THE AIR Fill a tin cup with ice cubes. Soon the outside of the cup will be covered with drops of water. Dry the cup. More drops will form. But the cup does not leak. The water must come from the air. When water. vapor in the air is chilled, it turns into liquid water. This happens when water vapor touches the cold cup.
9 cans of snow
1 can of water
SNOW AND ICE SNOW comes from cold, moist air. The
Ice that covers the ground or a pond
snowflakes form when water vapor
is as hard as a rock. It forms when
turns into ice without first turning into
liquid water freezes. It also is made of
liquid. The snowflakes are really little
crystals. But the crystals are so close
ice crystals, each with six sides.
together that you can't tell where one
The smallest snowflakes are made of
ends and the next begins.
single crystals. Sometimes they fall.
Sometimes snow melts, then freezes
But if gusts of air hold them up, they
again as ice. This often happens on
grow into bigger flakes. The big flakes
snowy roads. Passing cars press on the
have six sides, too. They look like
snow and this makes it melt. If the air
dainty pieces of lace.
is cold enough, the water freezes again
Air fills the space between the cry stals of the bigger flakes. The air makes them light for their size. So
they fall slowly and land quietly.
when the car has passed by. Thus the road becomes icy. When you make a snowball, the
heat and pressure of your hands melt
A blanket of snow is really a blanket
some of the flakes. The water quickly
of fluff. There is more air in it than
freezes to ice, which acts like glue.
water. You must melt nine or ten cups
Then the flakes stick together and
of snow to get one cup of water.
make a firm ball.
30
In cold weather we sometimes have
In summer, ice may fall from the
sleet. It is made of solid ice-not fluffy
sky. This is hail. Hailstones form high
flakes. Sleet forms when rain drops
above the earth where there are cold
pass through cold air and freeze.
winds. First, a raindrop freezes. It is
Winter may bring glaze, too. Glaze is an icy covering that forms on very
tossed by the winds and splashed with more water. This also fJ,"eezes.
cold objects when rain falls on them.
In this way, layer upon layer of ice
Glaze can be beautiful, but it makes
is added, and the hailstone may become
streets
slippery.
Its
as big as an egg. Finally it falls to
weight also may damage trees
and
earth. Large hailstones may damage
and
sidewalks
telephone wires.
crops, trees, and greenhouses.
Snow crystals seen through a magnifier
Thousands of snow crystals packed together
WArca A NO UTDOOR TiHERMoM When th ETER e the ometer or lowe nn 3 2 rea ds r de er w outdoors.' s gr�es ill freeze. Loo fi. o a r lee . p n of Water o . k how ut J e, and s lckly it freezes. I � � ee Watc IO f the a r s r snow. J l cloud y,
EXPERf M
ENrs
:r�
��
CATCH s NowFLAKEs Whe . . n 1t 1S s nowin c1 oth or a p per on a g_, put a piece of bla ck wlfldow . at t h e fl Sl ll "T'L akes wit .t n en . h l o o k Wlll fin agn i fyin d each g glass is Yt ou lu eren t. some of Tiry to dr th em. aw
�. �
·
·
RAIN BOW
COLORS
NEAR the end of a rain shower, you
that are like the waves in a pond. But
sometimes see the
turn
light waves are not all the same. The
away from it, you may see a beautiful
longest waves are the ones we see as
rainbow in the sky.
red light. The next longest waves are
sun.
If you
Every rainbow has the same colors
orange.
Then come yellow, green,
in it: red, orange, yellow, green, blue,
blue, and violet. When all six kinds of
and violet. These colors are always in
waves mix, they make white. Other
sunlight. When they are mixed, they
mixtures make other colors.
do not show. But when sunlight goes
If an object looks red, it is giving off
into raindrops, the colors are sepa
waves of red light. It may make this
rated. They come out one at a time.
light or reflect it from something else.
Then you see them.
But most red objects do neither. When
Colors are made only when objects
white light shines on them, they soak
give off light. In the dark, there are no
up all but the red waves. They reflect
colors.
these and so they look red. Other col
Light is never still. It travels in waves A rainbow.
ors also form in these three ways.
The colors mad e by sunlight shining through raind rops are beautiful.
EXPERIMENT
M AKE A RAINBOW
Tum on a garden hose. Stand with your back to the sun. Hold the hose so that sun light goes through the spray. You will see the rainbow colors. Hold a cut-glass crystal in sunlight. The crystal will work as the raindrops do. It will sort out the colors in sunlight.
EXPERIMENT
M AKE
A
RAINBOW M IXER
If you mix light from rainbow colors, you will get white, the color of sunlight. Cut a cardboard circle five inches wide. Punch two holes near the center. Coat the edges of the holes with glue or shellac. Let this dry. Cut another circle the same size from white paper. Color this circle like the one in the picture. Paste it on the cardboard. Punch two holes in it by pushing a pencil point through the holes in the cardboard. Thread about four feet of string through each of the two holes. Tie the ends together as shown. Now place the wheel in the middle and hold the string by the ends. Twirl the wheel until the string is tightly twisted. Now pull the string. Watch the wheel spin. See what happens to the rainbow colors as they mix. They turn to gray-almost white. If the colors were pure, they would tum pure white.
Above the clouds and rain.
The airliner's shadow falls o n top o f the clouds. The underside o f the clouds i s dark.
LIGHT AND
SHADOW
THE SUN shines every day. But some
From the ground, you see only the
days you cannot see it. Thick clouds
bottom of the clouds. That part looks
hide the sun.
gray because sunlight can not reach it.
If you fly above those clouds in an
Sometimes clouds cast shadows on
airplane, you see the sun above them.
the ground. Anything that keeps light
Its light makes the top of the clouds
from going through it makes a shadow.
look pearly white.
On a sunny day, you find a shadow, or shade, under a leafy tree. The leaves and branches stop sunlight from reaching the ground. A house casts a shadow. In the morn ing, the sun is in the east. Its rays fall on the east side of the house. But they
cannot go through. So the west side is Welcome shadows. trees
on
a hot day.
We are glad for the shadows of
Shadows through the day.
Shadows are long at sunrise, short at noon, and long again when the sun sets.
in shadow. In the afternoon, the sun is in the western sky. Its rays fall on the west side of the house. But they cannot go through. So the east side is in shadow. People used to tell time by shadows. They would set up a stick and watch its shadow shorten and lengthen and move. The stick was called a shadow clock or sun dial.
CAST
A
SHADOw
Set a pencil in a box of sand. Turn out the lights. Use a flashlight as the sun . Have it rise from the floor on one side of the pencil. Have it climb high ovr e the pencil. Have it set on the other side. Watch the shadow
change.
Use a big lamp as the sun. Walk up close the lamp. Then walk away. Watch your shadow change.
to
MAD SHADOw FIGURES Set a lamp so that it shine s on a light wall. on the lamp, but darken the rest of the between the lamp and wall. sh-aP-es you can make on the wall.
Telling time. The moving shadow of a sundial tells the time.
THE
BIG
RO U N D WO R L D
IN THE sky is a great big ball of rock.
see a distant ship. Only the top shows.
Water, sand, and soil cover most of the
The lower part is hidden by the earth's
rock. Green plants grow in the soil .
curve. If the earth were flat, you could
And animals crawl among the plants .
see the whole ship. Anything
Some creatures walk about on two legs . They speak different languages . How can you see this wonderful
all around the world . No one ever falls off. A strong force pulls everyone and everything down
earth. From the ground, you cannot see how the earth is shaped . When you look across fields, the land seems flat.
toward the earth's center. This force .
IS
.
gravity. Anyone
who
jumps
must
work
When you look at the sea, the water
against gravity. Anyone who falls is
seems flat. You are looking at only a
pulled down by gravity .
small part of the big earth. And a small part of a big ball looks flat. Yet there is a way to tell the earth i s round. At the seashore, you often
Proving the world is round.
� .
But the
earth has no ends . People can travel
place? Just look around you. It is the
"'!.._
flat has ends .
--
This force holds down sand and soil . It keeps water from spilling out of the sea . Without gravity, everything would fly away .
As a ship sails away, more and more of it becomes hid den by the curve of the earth.
. _.. .
----� -. .........-----. -�"- - �=...... ....___ �_.... :::...36
Oop1--no gravity!
Without gravity, everything on the earth would be
thrown off into space, just as mud is thrown off a whirling wheel.
EXPERIMENTS
A SHIP AT SEA M ake a little paper boat. T hen ask a friend to move it on a globe. Stand on the opposite side of the globe. Watch the ship sail toward you. You see the top fi rst, just as you do when a distant ship sails into port.
WHY THE EARTH SEEMS FLAT Take three balls of different sizes. With a tape measure, mark off a one-inch line on each ball. Run your finger over the lines. Notice that the line on the biggest ball curves the least. On a huge ball, like the earth, a line a mile long has only a very slight curve-so slight that it doesn' t show.
D AY AN D
NI GHT
OuR EARTH is never still. It is always
Long ago, people thought something
spinning in the sky. Round and round
happened to the sun at night. People
it goes, like a top.
who lived near the sea thought the sun
The earth spins so steadily we never
fell into the water. Those who lived
feel it turn. Each spin takes the same
near hills thought the sun hid behind
time-24 hours. In that time, we have
the hills.
a day and a night. The earth turns us toward the sun, then away from it.
But now we know the sun is always in the sky. We see the sun rise as our
When our side of the earth is toward
part of the earth turns toward it. And
the sun, we get some of its light. We
we see the sun set as we turn away
have day. But the other side is dark.
from it. Sunlight cannot go through the
There it is night.
earth. So one part is always covered
We have night when our side of the
with a big shadow. This shadow makes
earth is away from the sun. Then the
night. The pictures above show how
other side has day.
the shadow travels around the world.
38
EXPERIMENT
SEE DAY
AND
NIGHT
Get a globe. Use a piece of tape to stick
See how the shadow of the marker moves.
a small marker on the land where you live.
It moves from side to side. It grows shorter
Get a flashlight. Then darken the room. Turn on the flashlight. Pretend it is the sun.
and longer again. That' s how shadows move on the spinning earth. When th e marker is
Now spin the globe.
in darkness, your home is having night.
Limestone
Gneiss Sandstone
Granite
Slate
Schist
H OW RO C KS W E R E
M AD E
RocK that is part of the earth's crust
Other kinds of rocks have no crystals.
has a special name . It is called bedrock .
You may find a speckled rock, made
Near your house, you may find only
of dark and light crystals . This is prob
one kind of bedrock . Perhaps you will
ably granite. Perhaps you will find
find some bedrock with a streak of dif
some gneiss (say it like "nice" ) . This
ferent rock running through it. Or you
rock is also made of dark and light
may see two kinds of bedrock side by
crystals. These form thick bands.
side . Along a cliff or canyon wall, you
Or you may discover a rock called
may see layers of different rock piled
schist. This is a flaky rock made of
one on top of the other.
little crystals in thin sheets. Some of
Stones are pieces of broken bedrock.
the crystals sparkle.
They are crumbs of the earth's crust.
A white, yellow, gray, or bluish
In most places, all the stones are made
rock without crystals may be lime
of the same kind of rock . They come
stone . Rock made of little sand grains
from the top layer of bedrock.
is sandstone.
It's fun to pick up stones and see if
Slate breaks into thin sheets. It is
they match the bedrock . In some kinds
gray, red, green, or purple. Another
of rock, you find pretty glassy crystals .
rock that breaks into thin sheets is
40
Fossils
These three pieces of rock have imprints of plants. The middle piece also has the shells of prehistoric shellfish.
shale. It is found in the same colors as
of the minerals filled little spaces left
slate. But it is softer. It may crumble
by the decayed plants and animals. In
in your hand.
time, minerals replaced every part of
Rocks such as sandstone, limestone,
their bodies. And so they became fossils.
and shale often have traces of strange
Rocks made of crystals have no fos
plants and animals in them. These
sils, for they formed in a different way.
traces are called fossils.
Some are parts of the earth's crust that
All rocks with fossils were made
were once very hot. In some places,
from sand, mud, or other soft, wet
the hot material spouted from vol
material. Dead plants and animals were
canoes as lava. In others, it cooled
covered by these materials and decayed
inside the earth before it could get out.
slowly. New layers of earth piled on
Most rocks that you see were under
top of old ones and pressed down on
ground for ages. Layers of soil covered
them. Slowly the lower layers turned
them. But rivers, rain, and wind slowly
to stone.
worked on the layers and wore them
Meanwhile, water, carrying miner als, dripped through the layers. Some
away. Now rock that was once buried is part of the earth's upper crust.
EXPERIMENTS
O PEN
UP
STONES
To s ee what is inside a s tone, break it. Put it in a paper bag. Then hit it with a hard stone or a heavy hammer. START A SToNE CoLLECTION Look for s tones wherever you go. Keep different kinds in an egg carton or in a tool box. Or s tick them on a board with a dab of glue.
41
T h e earth's crust.
WHAT
If you could dig deep enough, you would ftnd layers and layers of bedrock under the soil.
I S I N SID E
THE
EART H ?
DID YOU ever dig a deep hole? Perhaps
deep mines, they find the earth be
you tried to dig to China. But you
comes hotter and hotter. Way down, it
gave up, for digging is hard work.
-must be hot enough to melt rock. Prob
What would you find if you kept on digging? After the soil you might find sand. Sooner or later you would come to rock.
ably that's what is inside the earth melted rock. The deepest hole made so far is an oil well . It goes down about five miles.
Rock is always under you. Even
Five miles is only a small part of the
when you sail in a boat, rock is under
way to the earth's center. From the
you. The bottom of a river, a lake, or
outside to the center is 4,000 miles.
the sea may be covered with mud or
In the earth's crust there are many
sand . But under that lies hard rock.
deep cracks. Sometimes a big chunk of
A shell of hard rock covers the
the crust will sink a little and other
whole earth. We call this shell the
chunks around it will rise. The earth
earth's crust. In some places the crust
trembles. We feel an earthquake.
shows. Rock sticks out of the ground .
Volcanoes start when melted rock
It forms hills, cliffs, and mountains .
creeps up through cracks in the crust.
But most of the crust is hidden.
If the melted rock finds an opening in
The e a r t h ' s h a r d cru s t v a r i e s i n
the earth's surface, it will flow out. If
thickness, and no one really knows just
it finds no opening, it may burst out
what is under it. As men go down into
with a big explosion .
42
U nder the earth's crust.
basalt.
The outsid e shell of the ea rth is mostly granite.
Next is a shell of heavier, d a rker rock called
The core of the ea rth is proba bly melted nickel and iron, but no steam shovel can dig down far enough to g et it!
LooK FOR THE EARTH' s CRUST I f workmen are digging near your house, watch the hole grow. Maybe the workmen will strike rock. When y ou go for a walk, watch for places where the road cuts through the rock. Also look along the sides of cliffs, hills, and canyons for rock.
-
This great block of bedrock remained a fter softer bedrock
This cave formed a s water seeped through limestone and
a round it was worn away.
d issolved away some pa rts of it.
43
PEBBLES THE PEBBLES along a beach come from
It is fun to make a collection of
cliffs near the edge of the sea. Pieces
pebbles. In a short walk along the sea
of rock break off the cliffs and fall into
shore, you may find dozens of different
the water. Waves toss them about.
kinds. The big pebbles are very hand
The pieces break into smaller and
some, but smaller ones are better for a
smaller stones . The stones bash into
collection. Mount each pebble with a
each other. And they crash against the
dab of glue on a sheet of plywood.
cliffs. Their sharp edges are knocked
How can there be so many different
off. The waves pick up sand, and the
kinds of pebbles along a seashore? Here
sand rubs against the
there were once layers and layers of
stones.
This
makes them smooth. You can find pebbles in streams and along the banks of rivers, too. Running
rock containing many kinds of miner als. From those layers of rock came the many kinds of pebbles.
water often carries stones and sand.
When at the seashore, watch how the
The stones bounce against each other
waves keep washing the pebbles back
while sand scours them. The bouncing
and forth. This goes on for hundreds
and scouring turn them into smooth,
and thousands of years. The pebbles
round pebbles.
will some day be worn to sand.
44
EXPERIMENT
RuN A PEBBLE FAcTORY Get some small stones with sharp edges. Put them in a coffee can and cover them with water. Put the lid on the can. Shake it 1 00 times. Ask each of your friends to shake
it 1 00 times. Then see if rounder. It takes a l ong smooth pebbles from rough takes a long time outdoors,
the stones are time to make stones . B ut this too.
45
Beach sand.
As waves grind pebbles a g ainst each other, beach sand is made.
SA ND
AND
WHERE DOES all the sand on a beach come from? The sand grains are little pieces of rock. They are pieces that were chipped off larger pieces.
SOI L
eats into the rocks and makes· them crumble. Bit by bit, the rocks wear away. A little sand forms. Winds pick it up
Desert sand forms in a different way.
and hurl it against the rocks. Chips are
Very few plants grow in a desert. In
knocked off the rocks. These chips are
many places, big bare rocks rise above
sand grains. They help make more
the ground. Now and then, there is
sand as winds blow them about.
some rain. The water gathers in cracks
Nothing can grow in plain beach or
and hollows of the rocks. Gases of the
desert sand. The water runs
air mix with it. This mixture slowly
through it when there is rain. The
Desert sand.
Air, water, and wind-blown sand wea r away the rocks to ma ke the sands of the d esert.
right
Soil and water.
Form crops need plenty of water.
soil (upper drawing) stores water for crops.
Good
In sand (lower
drawing), water runs down between Iorge sand groins and is lost.
spaces between -the grains are too large
tiny. After a rain, water is trapped in
to store water . Also, pure sand does
the little spaces.
not contain any food for plants.
When seeds fall into soil, they sprout
Soil is different. It contains materials
and grow. When the plants die, their
that plants can use for food. It holds
dead leaves and stems drop into the
water like a sponge. Pick up a handful
soil. They rot and make the material
of soil and see how soft it is.
called humus. Humus, which gives the
Soil is mostly a mixture of tiny bits
soil a dark color, is a food for plants.
of rock. Some sand is in it. But most of
Thus the plants that die become food
the rock particles are smaller than sand
for living plants, and these in turn die
grains. The spaces between them are
and make food for still other plants.
47
LAN D
AN D
SE A
THE EARTH'S crust is very uneven. Some
filled with deep water. This water
parts rise higher than others. Some of
makes the oceans. The oceans run to
the higher parts form big bodies of land
gether, making one big sea.
that are called continents.
The crust at the bottom of the sea is
High mountains tower above the
rough. It is as uneven as the crust of
rest of the land in some places. These
the continents. There are canyons and
mountains run for miles. Between them
cliffs under the sea. Mountains rise
are long valleys. Big wrinkles in the crust make the mountains and valleys.
from its floor. Some rise so high their tops stick out above the water. The
The lower parts of the crust are
tops of these mountains make islands.
G o l d e n E X P L O R I N G E A R T H B O O K S t r a v e l f a r b e yo n d t h e b o u n d a r i e s of t h e p r i n t e d p a g e . T h ey l e ad r e a d e r s o n ex c i t i n g e x p e d i t i o n s - w h et h e r i n t h e m i n d o r o n foot - a n d o p e n t h e i r eyes t o t h e m a n y f a s c i n at i o n s o f t h e n at u ra l w o r l d . E a c h b o o k i n t h e s e r i e s i s a n a d ve n t u r e f o r t h e y o u n g n at u r e l ov e r o r b e g i n n i n g sc i e n t i st w h o w i s h es to b e b et t e r a c q u a i n t e d w i t h o u r earth and i t s many m arve l s .
G o l d e n E X P LO R I N G E A R T H B oo ks F LO W E R S , T R E E S, A N D G A R D E N I N G
O C EA N O G R A P H Y
ASTR O N O M Y
R E PT I L E S A N D A M P H I B I A N S
N AT U R E H I K E S
A N I M A LS
R O C K S A N D M I N E R ALS
D I N O SA U R S
I N S ECTS
O U R 50 U N I T E D STAT E S
SCI E N C E
B I R DS
T H E H U M A N B O DY
H-0 S E S
