10 BEDS OF STREAMS.

 

 

 

21. Beds of Streams.

The bottom
of a stream is
called the bed
of the stream.

We have
seen how rills
and brooks
carry away
soil. Swift
rivers often
wash tons and
tons of sand, pebbles,
and even large stones
down the slopes.

This rocky matter
grinds the beds and
thus helps to wear
them away.

In some rivers,
floating ice cuts the
banks and beds. Mud, sand and stones
are held by ice, and are carried down
the streams. Where does the ice leave
its load?

With a hammer break a stone imto
small pieces. What is the shape of the
pieces? Are they rough or smooth?

Put the pieces into a bottle and
shake it very hard. See the grains of
rock on the bottom of the bottle.

Most of the stones in river beds are round and smooth. Can you
tell what rounded them ?

A part of the sand in river beds is worn from these stones.

What becomes of the fine particles that are worn off the rocks by
rivers? After long ages what will become of the rocks that are
now in river beds?

Rivers often wear steep places in their beds. The water leaps
down, forming waterfalls. A great fall of water over a steep bank is
called a cataract. A little fall is a cascade.

Some of the pictures show water phmging over steep rocks. One
shows the rocks back of the falls.