Nature’s ditches
What parts of the earth’s surface have floors and walls?
Valleys. A valley is like a long ditch scooped out of the ground. The
bottom of the ditch is called the floor. The sides are called valley
walls.
Some valleys are places where the ground has sunk. But most valleys are
made by rivers and streams. As water flows along, it tears away bits of
the land. As years go by, more and more land is worn away. The river
sinks deeper and deeper. Steep walls form on both sides of it. Then wind
and rain begin to wear away the walls, making the valley wider. In time,
the valley becomes a long, V-shaped ditch, with the river or stream
flowing along the floor.
Some valleys have grown so wide that they are no longer V-shaped. Some
are U-shaped. Others have become deeper rather than wider. Very deep
valleys with steep walls are called canyons or gorges.
Oneonta Gorge, Oregon
A valley is like a long ditch scooped out of the ground. Most valleys
are made by rivers that carry away tons of rock and dirt every year.
During many thousands of years, the valley grows deeper and broader.
Valleys with very steep walls are called canyons or gorges.
Rhone Valley, Switzerland
