over, again and again, the substance of
the earth's crust. Chemical and physical changes constantly tear down
some portions of the earth to build up others. The constant, combined
effort of wind and water is to level the earth and fill up the ocean
bed. Rocks are constantly being formed; the changes that have been going
on since the world began are still in progress. We can see them all
about us on any and every day of our lives.

GETTING ACQUAINTED WITH A RIVER

I have two friends whose childhood was spent in a home on the banks of a
noble eastern river. Their father taught the boy and the girl to row a
boat, and later each learned the more difficult art of managing a canoe.
On holidays they enjoyed no pleasure so much as a picnic on the
river-bank at some point that could be reached by rowing. As they grew
older, longer trips were planned, and the river was explored as far as
it was navigable by boat or canoe. Last summer when vacation came, these
two carried out a long-cherished plan to find the beginning of the
river--to follow it to its source. So they left home, and canoed
up-stream, until the stream became a brook, so shallow they could go no
farther. Then they followed it on foot--wading, climbing, making little
detours, but never losing the little river. At last they came to the
beginning of it--a tiny rivulet trickled out of the side of a hill,
filling a wooden keg that formed a basin, where thirsty passers-by could
stoop and drink. They decided to mark the spring, so that people who
found it later, and were refreshed by its clear water, might know that
here was born the greatest river of a great state. But they were not the
original discoverers. Above the spring, a board was nailed to a tree,
saying that this is the headwater of the river with the beautiful Indian
name, Susquehanna.

It was a dry summer, and the overflow of the basin was almost all drunk
up by the thirsty ground. They could scarcely follow it, except by the
groove cut by the rivulet in seasons when the flow was greater. They
followed the runaway brook, through the grass roots, that almost hid it.
As the ground grew steeper, it hurried faster. Soon it gathered the
water of other springs, which hurried toward it in small rivulets,
because its level was lower. Water always seeks the lowest level it can
find. Sometimes marshy spots were reached where water stood in the holes
made by the feet of cattle that came there to drink. The water