The following activities demonstrate the formation of mineral deposits on the surface and in the interior of the earth.

a. Salt deposits can be found in various locations on the earth's surface. To show how they may be formed, put a small amount of salt into a jar of water and shake it. What happens to the salt? (It seems to disappear as it dissolves.)

Continue adding spoons of salt until some salt remains in the bottom of the jar even after a thorough shaking. Pour the water into a shallow pan, and set the pan in a sunny place to let the water evaporate naturally. Describe the results.

Where on the earth's surface have similar salt deposits been found? The Great Salt Lake in Utah is not the only salt deposit on the surface of the earth.

Salts in the earth are continually being dissolved by water. Where does the water usually take the salts?

Describe the ocean's taste and relate your description to this activity.

b. Stalactites and stalagmites build up in caves from the dissolving and depositing of minerals by water. To illustrate the formation of stalactites, which hang down from the ceilings of some caves, and stalagmites, which stand upright on the floors of some caves (usually under stalactites), dissolve as much Epsom salts as you can in a container of water.

Fill two smaller containers with this solution.

Set the containers on paper toweling, then put one end of a thick string in each container, and suspend the string between them. Candle-wick is good material for this.

Let the string remain in place for several days. You will see that water soaks the entire string and drips off of the string at the low point between the containers.

You will also see that deposits form where the water drips -- both from the string and on the toweling. The deposits are carried in solution to the drip point, and when the water in a solution evaporates, the mineral -- in this case, Epsom salts -- is left behind.

You will realize that this formation is similar to the slow formation of stalactites and stalagmites in caves.