Lacy Lee Thomas, age 13, of Houston, Texas, for the question:

What is erosion?

Erosion is the wearing away of the earth's crust by wind and water. Running streams bite into soft soils, sandstones and limestones, creating canyons and steep sided gullies. Wind erodes the earth's surface by blowing dust and sand from one place to another. Strong desert winds blow sand on the face of sturdy boulders. This action may create mesas and work like emery board to polish the tops and sides of hard cliffs.

One of the farmer's worst enemies is erosion. It can strip away his best top soil and the eroded I‑and left is no use for growing crops. Nor will it recover in time for the present owner to use it, for it takes Nature about 100 years to form one inch of soil. For this reason the wise farmer prevents erosion with contour plowing and other tricks to save his soil from being stolen by the weather.