Article written by Dr. E. A. Shinn, Ph.D., Courtesy Professor, University of South Florida, Marine Science Center:

West Florida beaches are blessed with especially clean sugar-white sand. Louisiana and Texas are not so blessed. There is a good reason for the difference. It’s all about geology, wind, and tide. Not all sand is created equal. The sugar-like beach sands east of the Mississippi have a distinctly different source than sand in Louisiana and Texas. Over millions of years, quartz, the mineral used to make glass, has been weathered from granite in the Appalachian Mountains. Streams and rivers wash the quartz sand grains to the shore, where they begin a long and torturous journey. The journey is mostly southward as sand grains are propelled along by a process called longshore drift. Speed and direction of this drift are controlled by wind, tide, and wave direction. When waves approach the beach at an angle, a slurry of sand and water sloshes up the beach at a slight angle. The waves set up a current that moves away from the wind. When the sand and water slosh back down after each wave, the slurry moves with the current. Some sand, seaweed, trash, and shells remain stranded on the beach. The repeated up-and-down zigzag movement over hundreds, thousands, and even millions of years inevitably transports vast amounts of sand. It took a long time, but sand at the south tip of Key Biscayne off Miami came all the way from Georgia!

Our white West Coast sand took a similar southward route after emerging from rivers and streams like the Suwannee and Apalachicola. In the end, size, composition, and color were determined both by the source and by abrasion that takes place during transport. During the countless zigs and zags, grains become smaller, and some are ground away to nothing or become mud and clay! Look at what happens around groins and jetties. Sand piles up on one side (the direction from which sand is moving) while being removed on the other side (the direction to which sand is moving). St. Petersburg and most of Pinellas County are actually an old barrier island that accumulated during the Ice Ages when sea level was higher than now. The building of beaches, barrier islands, and sand spits are the stuff of countless geological textbooks the world over.

Louisiana and Texas are another matter all together. Most of their sand came from the U.S. heartland via the mighty, and muddy, Mississippi. Their sand was washed from the gooey brown clay that is the Mississippi Delta. The delta sticks way out into the Gulf of Mexico, effectively blocking any westward transport of Appalachian sand.

Sand from the heartland contains quartz along with dark-colored mineral grains, charcoal, and other organic matter. This grey sand does become increasingly lighter in color as it zigzags toward Corpus Christi and the Mexican border beyond. This difference in source and impedance effect of the Mississippi Delta are the major reasons we have white sugar-like sand beaches while Texas and Louisiana have sand that looks more like brown sugar. The color of their sand has nothing to do with offshore drilling! Another factor is the miles and miles of muddy soft sediment off Texas and Louisiana. Storms stir that sediment into suspension, making beach water look like café-au-lait. Off west Florida, we have more than 100 miles of hard limestone and far less sediment to stir up. Even farther out into the Gulf, the limestone shelf drops abruptly into a totally different environment, the deep Gulf.

A gigantic blanket of thick salt underlies the deep Gulf. These vastly different terrains, created when dinosaurs roamed the Earth, were formed during the breakup of the giant continent to form the Americas and the Atlantic Ocean. Under the weight of mud and sand, salt under the deep Gulf is constantly being squeezed upward like thick molasses. Movement of salt is slow but relentless, creating underwater hills and valleys that geologists call salt domes. Salt domes come in many shapes and sizes but have one feature in common. They form an almost impenetrable seal that can trap oil and gas. Salt domes of various shapes and sizes are the major drilling targets in the deep Gulf. These features also tend to leak some of the oil and gas as hydrocarbons slowly ooze upward.

There are hundreds of documented salt domes that leak oil and gas off Texas and Louisiana. They have been leaking for millions of years. Several studies show that for the entire Gulf of Mexico, between 1,000 and 2,000 barrels leak to the surface each day! Native Americans were sealing canoes and pottery with tar from Texas beaches more than 1,000 years ago. We can be thankful that there are no active salt domes on our stable limestone shelf and that we are far enough away so bacteria can consume and degrade the crude before it reaches our beaches. Texas is not so lucky. Their beaches are closer to the natural seeps.

So, what does this geological information have to do with our decision to drill or not to drill? First, the decision makers need to know that at least 95% of all oil in the world oceans originates from a combination of tankers and cargo-ship bilges, tanker accidents (like the one we had in Tampa Bay in 1993), natural seeps, and runoff from land. About 6 billion gallons of various oils presently transit in ships through Tampa Bay each year, and our gas comes through Tampa Bay via a 580-mile-long offshore pipeline from Mississippi. So, a major question before us is, would oil and gas drilling be safer for our beaches and tourism than importing foreign oil in tankers? Hopefully, cool heads will prevail as this difficult political debate continues to simmer and boil.