Posts Tagged ‘Carolina Bays migrated’

Migrating Carolina Bays

December 21, 2019

Referenced within the study I wrote about last week was another interesting paper that determined some Carolina Bays migrated.  I’ve written about Carolina Bays previously (See: https://markgelbart.wordpress.com/2012/04/30/a-young-carolina-bay-in-north-carolina/ ), but I did not know this.  Carolina Bays are elliptically-shaped depressions found in the Carolinas and Georgia, mostly on the coastal plain.  Wind and water erosion during wildly fluctuating Ice Age climates created these fascinating geological features.  Some are in the process of originating now.  Wind during cold arid climate cycles blew out unconsolidated sediment, and wind-driven water during wetter warmer cycles shaped them.  They vary in size and water content.  Some hold water year round, while others are seasonally dry.  They provide important wetland habitat, especially for amphibians because frog and salamander-eating fish are often absent.  Like so many other natural features, a majority of them have been destroyed by development.  Farmers drain and plough over them.

Scientists studied Herndon Bay in North Carolina.  They used ground penetrating radar to find abandoned rims, also known as lips. The abandoned rims date to 36.7, 29.6, and 27.2 thousand years old, and these dates are associated with climate cycle transitions.  In between these dates Herndon Bay stabilized.  Apparently, Herndon Bay was pushed by wind and moved across the landscape in a process that was too slow for the human eye to follow.  It has stabilized at different locations, and one could say this is a kind of migration across the landscape.

Moore_Fig3

Ground Penetrating Radar Image from the below reference.  Note the former basins of Herndon Bay.  It has migrated across the landscape.

Image result for Carolina Bay

Carolina Bay located in Aiken, South Carolina.

Some crackpot scientists think Carolina Bays are craters formed by either comet impact ricochet or a comet striking a glacier, thus causing chunks of ice to fly thousands of miles before landing in southeastern North America.  A single fact debunks this idea–Carolina Bays originated at different times and some are still forming.  They are not the same age, ruling out a single extraterrestrial event.  There are 500,000 Carolina bays, yet less than 200 confirmed impact craters on earth, so this makes it seem highly unlikely as well that they result from multiple impacts.

Reference:

Moore, Christopher & Brooks, Mark & Mallinson, David & Parham, Peter & Ivester, Andrew & K. Feathers, James. (2016).

The Quaternary evolution of Herndon Bay, a Carolina Bay on the Coastal Plain of North Carolina (USA): implications for paleoclimate and oriented lake genesis.

Southeastern Geology. 51. 145-171.