STUDENT ANALYSIS OF QUATERNARY CLIMATE CHANGE AND PALEOECOLOGY ON THE NORTH CAROLINA COASTAL PLAIN

My paleontology classes are populated mostly with science education students who will teach earth science on the North Carolina coastal plain. The preponderance of Quaternary literature on glaciated areas or the pelagic ocean seems remote and not relevant. What is local and relevant are David Frey’s papers on the Quaternary pollen record from Carolina Bays, oval depressions of enigmatic origin common in southeastern North Carolina. This record shows significant changes in the local vegetation in a record that stretches back to at least the previous interglacial. The base of the record begins with a diverse pollen assemblage, similar to today, representing a previous interglacial. Then most of the angiosperm trees (e.g., Carya, Nyssa, Liquidambar) and Taxodium disappear. Pinus becomes much more abundant and Isoetes (quillwort) appears during the glacial. Then a deglaciation sequence occurs marked by re-appearance of the angiosperm trees and Taxodium with an increase in Compositae near the surface marking European settlement.

Students analyze basic taphonomy for pollen accumulation in lakes without significant fluvial input. They then divide the record into major intervals, compare their vegetation record, and make climate interpretations. They are also asked to determine the cause of the Compositae increase at the top. Students interpret lithological changes in the core (silt becomes more abundant in the glacial). Finally, they are asked to think about whether vegetation ever reaches equilibrium.

The origin of Carolina Bays has been attributed to a number of causes, some far-fetched. The exact cause is not well understood. Recently, it was suggested that an extraterrestrial impact about 12,900 years ago had effects across North America including megafaunal extinctions and, in early versions, ejecta that produced the Carolina Bays. I ask students to determine, even without radiocarbon dates, how this aspect of the impact hypothesis can’t be correct based on the pollen record of the Bay fill.

This exercise provides an opportunity for students to analyze a local multivariate dataset that changes complexly and place changing vegetation in a larger climate change context, even in an unglaciated region.