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Show Soil and Water Conservation Activities for " fourth I. Make Some Soil Artificially Students can show how some of the forces of nature break down rocks into soil material by several simple demonstrations: 1. Rub two pieces of limestone or fine sandstone together. If you do not have natural stone, pieces of building bricks or concrete will do. Notice how long it takes to rub off even a few fine particles. 2. Heat a small piece of limestone over a flame or on a hot plate. Drop it quickly into a pan of ice water. The rock should break or crack as it contracts after its expansion by heating. 3. Fill a small discarded glass jar with water and cap it tightly. Let it freeze outdoors or in the freezing compartment of a refrigerator. Note what happens to the jar. 32 X 4. Put some small pieces of limestone in a little vinegar. Heat the vinegar on a hot plate or over a burner and notice how bubbles form on the pieces of stone. These bubbles are carbon dioxide gas made from carbon and oxygen released from the limestone by a chemical change in the rock caused by the acid in the vinegar. If you continued this process long enough, all the limestone would gradually break down. |