Solving an Earth Mystery Not So Far From Home
From my virtual vantage point thirty miles above the swamp forests and sandy flats of the South Carolina coastal plain, I navigated Google Earth along and well to either side of our anticipated travels from Goose Creek to the doorstep of some Floyd friends who still live part time in Conway near Myrtle Beach.
For me, getting map routes ready for a trip like this is about as much of the joy of the journey as the travel itself. And here, I was exploring both new and known country.
Below me was a landscape familiar and comfortable, little different from the coastal plain of Mississippi where my wife grew up and where we often visited after the kids came along. The land I watched passing below me would have been saturated for a good bit of the year, the water table very close to the surface.
So it surprised me to see to what extent coastal Carolina had turned the too-wet pine pocosins and savannahs into tract housing and strip malls, apparent even from many miles in space.
But what puzzled me most in “flying” over this area for the first time were the oblong shapes imprinted in the ground. The ones I noticed first were labeled on the map as “Pee Dee Islands”. Though the Pee Dee is a river, these so-called islands were high and dry, egg-shaped, the largest a mile long and three fourths as wide.
The more I explored along the coastal plane of both South and North Carolina, the more of these odd rimmed areas I could clearly see. Some cover only a few acres, most green with vegetation. Some (the largest being 7-mile-long Lake Waccamaw in North Carolina) are filled with water.
A great many of the larger ones are oval in shape, slightly elongated along a North-west to South-east axis. In places, they partially or almost completely overlap each other, splattered across the land like so many giant droplets blown by an invisible wind against cypress swamp or lowland forest. What is going on here?
I am by no means the first to wonder about this. The elliptical shapes and vast distribution of these earth forms, now known as “Carolina Bays”, were not appreciated until 1933 when the first aerial photos of the area brought this oddity back for study.
Extending from southern New Jersey to northern Florida, there are at least 500,000 such ellipical depressions– called bays because of the shrub and tree species that typically fill them, and so distinctive from surrounding land that they are indeed often called “islands.” You can download a Google Earth overlay that outlines vast numbers of them from several counties in North Carolina, but they are clearly visible without such assistance. Just look south of Fayetteville on Google Earth (free download). There are also some more recently discovered bays near Midlothian in Virginia.
So surely, seventy five years after their discovery, we must know why they exist and how and when they were formed. No, as a matter of fact, we don’t. The explanations fall into two main camps: terrestrial causes and extra-terrestrial. Both have arguments in favor, both lack the “smoking gun” to say with certainty that the case is closed.
While the theory isn’t fully substantiated by any means, I find most interesting the explanation that an air-burst cometary explosion splashed these half million bays onto the landscape, but no meteorite fragments are found below the bays.
The closest and most notable air-burst event in historical times is the Tunguska phenomenon over Siberia in 1908. Trees were scorched and blown down over a 30 mile radius, but as with the Carolina bays, no meteor material was ever found. A similar mid-air explosion or earth impact may explain the geologically sudden Ice Age disappearance (about 13,000 years ago) of previously abundant large mammals like the mammoth (some instantly freeze-dried with food still in their mouths.)
Based on dating of the sediments in some of them, the Carolina Bays may have been formed at this time of world-wide cataclysm. Or they might have formed more gradually from natural processes of wind and groundwater, dune and ocean currents. The jury is very much undecided, while anyone can now see the evidence.
While the Phoenix lander probes the Angry Red Planet for answers, I encourage you to take a look for yourself at a mystery a little closer to home.