Faunal Comparison and Analysis of the Blufftown Formation-Cusseta Sand Contact at Hannahatchee Creek, Georgia
Date of Award
Honors College Thesis
Geography and Geology
Alyson A. Brink, Ph.D.
Geography and Geology
The origin of fossil material in the highly fossiliferous bed above the Upper Cretaceous (Campanian) Blufftown Formation-Cusseta Sand contact at Hannahatchee Creek, Georgia, has long been a subject of scientific curiosity; however, no research has yet been conducted to specifically investigate discrepancies between the fossil assemblages of the upper Blufftown Formation and the basal Cusseta Sand, which overlies it unconformably. In the most recent published hypothesis, Case and Schwimmer (1988) propose that the basal Cusseta Sand contains a mixture of original fauna as well as material reworked and redeposited from the underlying Blufftown Formation, resulting in a lag deposit above the contact. Analysis of fossils discovered in 294 g of concentrate samples collected from the upper Blufftown Formation and basal Cusseta Sand reveals distinct incongruities between the fossil assemblages. Fossils from the Cusseta Sand range in quality from well preserved or angularly fractured to heavily fragmented and rounded, whereas fossils from the Blufftown Formation are consistently and extremely weathered, with highly fragmentary and pitted specimens and invertebrate internal molds devoid of original shell material. The degree of weathering observed on the Blufftown Formation specimens is inconsistent with a majority of specimens from the Cusseta Sand sample. The Cusseta Sand sample also contains a more diverse fossil assemblage compared to the Blufftown Formation. The higher diversity characteristics of the Cusseta may be related to the presence of a Crassostrea cusseta oyster bioherm found in the same horizon as the Cusseta Sand assemblage at the locality, as contemporary oyster reefs provide a habitat for a diverse array of fauna. It is likely that some specimens original to the Blufftown v
Formation were reworked and deposited into the Cusseta Sand, but a majority of the fossil material present in the basal Cusseta assemblage is likely original to the Cusseta Sand.
Keywords: Blufftown Formation, Cusseta Sand, Hannahatchee Creek, Late Cretaceous, vertebrate paleontology, Georgia
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Fradella, Seth, "Faunal Comparison and Analysis of the Blufftown Formation-Cusseta Sand Contact at Hannahatchee Creek, Georgia" (2022). Honors Theses. 873.