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

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 in a jar of water and shake it.

[What happens to the salt? Does it seem 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.

Discuss the results.

Where on the earth's surface have similar salt deposits been found? Is this how we got the Great Salt Lake in Utah? What about the Bonneville Salt Flats?

Salts in the earth are continually being dissolved by water. Where does the water usually take the salts? There is basically only one place that water can take salts: to a larger body of water.

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

What are some other materials that dissolve in water? What materials would dissolve, then crystalize in a deposit?

b. Stalactites and stalagmites build up in caves from the dissolving and depositing of minerals by water.

Here's a fun activity! We will actually make stalactites and stalagmites, just like the ones in caves. (Remember stalactites by thinking "up tight," because they hang down from the ceilings of caves. Stalagmites rise up from the floors of caves, usually directly underneath the stalactites.)

Dissolve as much Epsom salts as you can in a container of water. Pour this solution into two smaller containers. Set the containers on paper toweling, then put one end of
a thick string in each container, and suspend the string between them. 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.

You can infer that the deposits are carried in solution to the drip point and that when the water in a solution evaporates, the mineral -- in this case, Epsom salts -- is left behind. This formation is similar to the slow formation of stalactites and stalagmites in caves.

Now if we could just figure out how to make some bats to go with the mineral deposits, we would have a good start on making a cave!