Research
Summer 2009 |
Abstract
North America’s Laurentide Ice Sheet reached its maximum extent approximately 20,000 years ago when its south-easternmost margin reached present day New Brunswick in central New Jersey. There is no evidence that successive glaciations preceding the most recent episode penetrated much further south than the Mason-Dixon demarcation in the eastern United States. However, topographical changes attributed to the harsh weather during glacial intervals are purported to remain visible far to the South. Prominent among these features are numerous elliptically shaped, shallow depressions called collectively Carolina Bays, hypothesized to have been formed by “blow outs” of loose sediment by the strong, sustained winds characteristic of glacial epochs. Approximately13,000 years ago, the Laurentide Ice Sheet’s retreat was interrupted by a return to glacial climatic conditions that persisted for over 1,000 years. The events precipitating the dramatic, millennial long climatic cooling known as the Younger Dryas remain both a mystery and the subject of debate. Some proposed mechanisms for initiating the YD hypothesize that Carolina Bay formation might be have occurred as a consequence of an extraterrestrial impact although evidence has been reported indicative of an earlier genesis. While some research has indicated the bays were formed during prior glacial epochs, there are also indications the bays may be more recent features formed during the Younger Dryas. If earlier, the bays would have experienced successive periods of post formation modification due to alternating cold, dry and warm, moist climatic conditions. In this event, Carolina Bays would episodically be filled with wind blown sediment or water. During the more clement periods, archeological evidence reveals the bays frequently became shallow ponds whose micro-ecosystems supported transient paleo-indian populations, camped on bay rims. Core samples and carbon 14 dating indicates Rockyhock Carolina Bay, north of Edenton, NC is far older than YD onset. Its proximity to ECSU makes it a candidate for application of Ground penetrating RADAR to determine if its physical structure is consistent with an pre-YD formation date. Therefore, to obtain a clearer understanding of the processes that shaped the coastal topography of North Carolina during the Younger Dryas or previous glaciations, Ground Penetrating RADAR (GPR) and coring to extract subsurface deposits of selected deposits of selected depressions were used as the sources of data.
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