SANDY FEET

Mention the word seashore and most people conjure up images of tranquility and the superb feeling of warm sand between the toes.

The fact is, the seashore is quite dynamic. It is always in a state of change brought about by the sand that makes up the beach, the energy forces driving against it (wind, waves and currents), the width and slope of the beach, and the constant changes in sea level.

Geologists say the barrier island known as Sand Key was formed about 3,500 years ago. It consists of thin layers of fine sand deposits (probably from the Ice Age) on bedrock which stretches 150 miles into the Gulf.

The sand you sit on today very likely will not be the same sand you'll sit on tomorrow. Studies have estimated that every year 100,000 tons of sand move by any given point on our beaches.

That's a lot of shifting sand. Some of this sand comes from offshore, brought in by waves. Other sand moves up and down the coast by currents, in what is called a littoral (or sideways) drift. Interestingly, near 7th Avenue in Indian Rocks Beach is the "headlands" - the part of Sand Key that juts furthest out into the Gulf. South of the headlands, sand has a net southerly movement; north of 7th Avenue, the net movement is northerly

Much of that white stuff we shake out of our shoes comes from inland, created by the action of rivers flowing to the sea. In our area, sand consists primarily of quartz and feldspar grains, derived from the weathering and erosion of rocks such as granite. It also contains fragments of clam shells, smoothed and rounded until they are the size of sand grains.

Sand is also loaded with the element silicon, which, next to oxygen, is one of the most abundant materials making up our planet. Silicon exists on earth only in combination with other elements, forming a wide range of silicate materials -- sand being a very familiar one. In recent years, silicon has become a household word because of its application in computers. Gee, just when you thought you could escape technology by going to the seashore, you find you're sitting right on top of its breeding ground!