16

are narrower than the bodies of water which
they connect.

In many places arms of water reach into
the land. Some of these are called bays,
some are called guifs, and others, seas.

_ There are bays, gulfs and seas so wide that
swift steamers cannot cross them in a day.

How does a bay differ from a peninsula ?

Turn to the picture’on page 9. If the tide
were to rise into these low valleys, where
~ would it first form islands? Where would it
form peninsulas ?

Can you find a place where there would be
first an island and then a strait? In what
parts of the valleys would there be the great-
est number of little bays?

26. Work of Water on Shores.

Let us visit the seashore and watch the
great waves roll in. How they roar as they
tumble over and over!’ Have you ever bathed
in the surf?

What is gravel? Which bank in the picture
is made of gravel ?

Waves often strike against this bank, and
wear parts of it away. Why does the water
not make the bank as steep as the rocky cliff?

Where do the pebbles and larger stones on
the beach come from ?

What becomes of the sand that falls with
the pebbles from the gravel cliff?

Find the clay cliff. Where do the large

stones on this shore come from? Find a

stone on the face of the cliff. When will —

it fall?

In some places ice rubs Deiat shores and
helps to cut and wear them away. Many
tons of sand, pebbles and even large stones
are held by the ice, and are carried out to sea
by it. What becomes of them when the ice
melts ?

WATER ON SHORES.

Waves often wash gravel against cliffs, and
thus slowly cut them away. Frost splits and
loosens the rocks. ae

Can you see the place where a part. of a
cliff has lately fallen? What will become
of the loose earth at the foot of the cliff?

Can you tell what made the caves in the
middle cliff?

Find the picture which shows surf breaking
over rocks. This rocky ledge was once a part
of the main shore. After a long time the
waves may wear away the whole ledge.

The island in the calm sea is like a low hill
round which water has flowed.

Have you ever seen seaweed growing on
rocks? Which do water and gravel wear away
more quickly, bare rocks or those which are
under seaweed ?

In some places the sand and pebbles that
are worn from soft cliffs and beaches spread
out and make the water shallow along the
shores. .

Great waves that roll in from the sea often
strike upon shallow bottoms, and wash sand
and pebbles up onto the beaches. In some
places the wind then blows the sand into
drifts, like snow, and carries it far mland.

Plants sometimes grow in beach sand, and
keep it from drifting. Which picture shows
a low, grassy shore ?

An arm of the sea, or of any other body

of water, in which ships find shelter from

storms, is called a harbor.

Some harbors are made by building long

walls out into the water. These walls break
the force of the waves.
- The best harbors have deep water and
high shores. Can you tell why deep water
is needed? Of what use are the. high
shores ?

Should you expect to find the best harbors
on rocky coasts, or on sandy ones ?