geologists and astronomers... please take a look at the coastline configuration of the NC/SC border, on...?

Question

a map or on Google Earth... There are two very prominent, roughly circle-shaped arcs of coastline, one in Horry County, South Carolina, and the other just north of it in Brunswick County, North Carolina. These are smooth, sandy beach areas. The coastlines to the north and to the south of these two arcs are very irregular and marshy.

There are also numerous "carolina bays" in both counties, which are unexplained, oval shaped indentations in the earth, ringed by sand ridges approximately 3-10 feet in height, and all oriented in a southeast to northwest direction.

I've heard that the two coastal arcs are merely tidally shaped features, but this strikes me as odd. Could the explanation be that they are really ancient impact craters from a meteor strike, wherein the meteor broke up into two large pieces and several hundred smaller pieces before striking the area? The smaller pieces might explain the carolina bays, and the two larger pieces might explain the two large beach arcs.

What do you think? Is my explanation possible, impossible, likely, unlikely?

The southernmost arc does extend a little bit into NC, up to Smith Island, which divides it from the northernmost of the two arcs.

Answer 1

You are not the first to think so:

"William F. Prouty's contention (1952) that the Carolina Bays were formed by impact has not been refuted by direct evidence nor has it been tested by more modern methods. Recently, however, several papers have been published which relate evidence that could be viewed as supportive of Prouty's hypothesis. For instance, P.S. Martin's "over-kill" scenario is in trouble due to finds of mammoths in Europe which date 5,000 years younger than earlier discovered specimens. This closes the gap between the youngest date for mammoths in America (10,500 B.P.) and for Europe (12,000 B.P.) to 1,500 years (see G.R. Coope and A.M. Lister, Nature Vol. 330, 3 Dec. 87, pp. 472-474)"

On the other hand (playing devil's advocate):

"Bays persistently turn up on amateur lists of meteor impact craters, but they are definitely not due to impact.

> There is no meteoritic material associated with them.
> The elliptical shape invites speculation about oblique impact. In fact, only the most grazing impacts produce elliptical craters. A crater is due to the instantaneous release of a meteorite's kinetic energy as heat, and that process will not depend on trajectory. Oblique impacts do produce a distinctive ejecta pattern. Ejecta is not thrown backwards toward the direction of approach, and ejecta thrown in the direction of travel will be flung upward. The only places ejecta will be hurled around the crater rim will be off to the sides, producing a two-lobed "butterfly" pattern. The bays show no hint of such a pattern.
> Impacts melt the target material, and impacts large enough to create these bays should have penetrated the soil, excavated bedrock, and produced distinctive signs of intense disturbance in the bedrock. There should also be plenty of bedrock ejecta around the bays. None of these features are present.

The formation mechanism of the bays is still imperfectly known but most geologists suspect they are the result of chemical weathering in a warm, moist climate with poor drainage."