Who doesn't like a mystery? Geologists and natural history enthusiasts have been trying to solve one for decades - the origin of an ancient collection of elliptical features called Carolina Bays, scattered over the Lowcountry coastal plain. The nearest to us is one in Francis Marion Forest, one of an estimated 4,000 such features throughout the state, according to the South Carolina DNR, ranging in size from just a few hundred feet across to the size of a small lake. No one knows where they came from.
They all share some intriguing similarities. They're all oriented along a northwest/southeast axis, and most have sand banks built up on their northeast and southeast edges. Erosion on the northwest and southeast edges have caused a general migration to the northwest. When supplied with water from underground aquifers, Carolina Bays support a plentiful array of wildlife and rare plant species along with loblollies, cypresses and sweet bay trees; drier bays have allowed geologists to date their formation through bedrock samples to as early as 20,000 years ago.
They remain mysterious even though they were first described in the late 17th century by a European explorer, John Lawson, during a months-long trek with Native American guides that took him from Charleston as far north as present-day Washington DC. Traveling up the Santee River, Lawson noted what his guides called "pocosins", swampy areas that, he wrote, were always studded with huge bay trees. The association eventually gave the features the common name we use today.
Theories abound about the origins of Carolina Bays. The most popular current theory is that they were created by the southwesterly winds of the late Pleistocene era that swept and buffeted left-over water from receding seas into the shapes we see today. Until recently, though, the bays were thought to have been created by a meteor impact somewhere near the Great Lakes, spewing debris south and east and creating depressions that retained water from the retreating ocean. Or they may be glacial in origin, gouged out of the earth as glaciers retreated at the end of the last Ice Age. But no one really knows, and the mystery remains.