Paper No. 39-0
SLADE, Laura L., Department of Geological Sciences, Indiana Univ, 1001 East 10th St, Bloomington, IN 47405, and WATERS, Johnny A., Department of Geosciences, State Univ of West Georgia, Carrollton, GA 30118

In 1978 Dr. Johnny A. Waters analyzed an erosional outlier of the lower Bangor Limestone (Chesterian) in Fox Trap, Alabama for faunal composition and community evolution. Trophically, a single community was interpreted as a typical middle-upper Paleozoic suspension feeding association. In this study, Waters’ interpretation of a single community that indicates a change from nearshore to offshore environments is tested with a variety of multivariate techniques including cluster analysis, polar ordination, and correspondence analysis. The resulting clusters, ordinations, and plots of the fossil abundances from the sampled beds are hypothesized to represent actual faunal associations and environmental gradients. The specific purpose for using cluster analysis with this data set is to delineate distinct associations of taxa and identify stratigraphic beds correlating with the clusters of taxa. Groups from a cluster analysis of the same data were plotted on the polar ordination in order to define distinct associations of beds or taxa. The evaluation of this comparison revealed three groups of taxa and three groups of beds that are understood to represent nearshore, transitional, and offshore settings. The primary axis from the correspondence analysis is interpreted to represent an environmental gradient from nearshore to offshore conditions. Overall, the lithologies of the beds increase in grain size, the abundance of gastropods and bivalves decreases, the abundance of echinoderms and bryozoans increases through the section, and brachiopods are present throughout the section. The results of this study agree with Water's interpretation of a single but maturing community that represents a shift from a low-energy nearshore environment to a higher energy offshore environment.

North-Central Section (36th) and Southeastern Section (51st), GSA Joint Annual Meeting (April 3–5, 2002)
Session No. 39--Booth# 5
Paleontology (Posters)
Heritage Hall: East
8:00 AM-12:00 PM, Friday, April 5, 2002

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