Northeastern Section - 40th Annual Meeting (March 14–16, 2005)

Paper No. 8
Presentation Time: 3:40 PM


RUEGER, Bruce F., Colby College, Department of Geology, 5806 Mayflower Hill, Waterville, ME 04901-8858,

The aerially exposed portions of Bermuda represent predominantly eolian carbonates derived from organisms living on the Bermuda Platform. Bermuda, therefore, offers a prime location for the observation of sediment-organism interactions and carbonate production and deposition. To consider these relationships, a January-term course was designed with an initial indoor laboratory component followed with an intensive field experience on Bermuda.

The laboratory component involved an introduction to the carbonate classification schemes of Folk and Dunham and students were given a suite of rocks to classify using both methods. Students were each given a different beach sand sample from the coast of Bermuda to analyze. Grain-size distribution and identification of the organisms that produced the sediment was a significant portion of the analysis. From these data they predicted the depositional energy for each beach, related it to geographical location on Bermuda and determined species diversity using a variety of statistical techniques. Thin sections were analyzed petrographically and components were identified. During these observations, amount and type of cement and porosity was noted. Reef structures on Bermuda were discussed. Additionally, students selected a topic related to the geology of Bermuda to study and results were presented in a day-long symposium.

The field component on Bermuda included a variety of observational and practical applications. Caves, both commercial and non-commercial were visited. Snorkeling trips visited both algal cup reefs and platform margin reefs to observe differences in organism composition and reef structure. Modern carbonate depositional environments were compared to rock and fossil examples. Organic sediments from ponds were cored to compare terrestrial sediments with marine. Students were also introduced to environmental issues related to island existence.

The laboratory component provided a strong foundation on which the field component could build. This format was extremely successful and produced favorable comments from student participants.