MUD. BANKS

Let us throw two or three pailfuls of gravel
into the rapids. See what takes place.

The pebbles sink in the rapids, where
the water is swift. Some are rolling down
the slope under the water. Can you tell
what moves them ?

Here is the sand below the rapids.
Watch it spreading on the bottom. It
looks like a great leaf. Why does
the sand settle here? Why did it
not settle in the rapids?

Look into the ,
pond where the
water is still. The
muddy water is
flowing into it.
Let us wait a lit-
tle while and find
out where the fine
soil goes.

The part of the
brook that flows
out of the pond is
not muddy. It has
left the fine soil
under the still
water.

If there were no
pond, what would
become of the
muddy water ?

f

Il. Mud Banks ‘oF Deltas.

Look once more at the mud on the bottom
of the pond.

When it rains again, more soil will be
brought down by the rills and brook. In
time a little mud bank will form near the
place where the brook flows into the pond.

When the water is low the mud will stand
above it.

 
 
  
 
 
 

OR DELTAS. 5

&

After a long time the soil may fill the
whole pond, except where the brook keeps a
path or channel open. As the new bank of
soil grows, grass and flowers will cover it, and
make it look like other parts of the field.

Thus, water wears
down the high land
and so makes the
slopes more even...

Mud banks that
form where streams
flow into still water
are called deltas. A
delta cannot form
in water that moves
swiftly. The soil
is swept away and
cannot settle.

Most of the rivers
in the world flow
into a great body of salt water,
called the ocean or the sea. Rivers
make many deltas on the shores of
the ocean. Some deltas are so
, iarge that cities are built on them.
= a Let us next find out where the
water in brooks and rivers comes
from.

Rapids.

  

12. Water and Heat.

Put a few drops of water into a tin
cup, and heat it. Where does the water go ?

The water in the cup changes into vapor.
cannot see the vapor, but it is floating in the air.

Heat a small bottle of water over a lamp. What
takes place inside the bottle ? What comes from the
bottle ?

Hold a piece of cold glass in the cloud that you can
see coming from the bottle. Of what is the cloud
made ?

Breathe against a cold window.
breath ?

Have you ever seen your breath ?
cold day or on a.warm one ?

We

What is in the

Was it on a