MODERN – ANCIENT COMPARISON AS THE FOCUS FOR A FIRST COURSE IN SEDIMENTOLOGY

Sedimentologists compare modern and ancient environments to interpret depositional environments. This is the approach I used in teaching Sedimentology during fall 2003, alternating between field trips and data gathering in modern and ancient environments. In Connecticut we are fortunate to have excellent exposures of both a short distance from campus. The Mesozoic Rift Basin includes alluvial fans, river sequences, playas and lakes, as well as excellent exposures of sedimentary structures and some trace fossils (especially dinosaur tracks). Lacking exposure of an alluvial fan, I substituted glacial deltaic deposits, which also have outstanding examples of sedimentary features. The glacial connection also provided us with an opportunity to discuss orbital forcing as a cause of the recent glacial cycles. Similar cycles are seen in the Mesozoic lake sediments (East Berlin Formation). We cored a small lake with some anoxic sediments. This was done in conjunction with the geochemistry class, which many of the students were taking, and allowed the students to perform numerous chemical analyses. To interpret the river deposits (New Haven Formation, Portland Formation), we viewed aerial photographs, sampled river sediments, viewed flume studies and interpreted multibeam images of the Connecticut River. For each environment students were asked to draw comparisons between the modern and ancient sediments and discuss how the material was studied.

For a final project students addressed the question: Is the Hartford Basin a good analogue for the Rift Basins of East Africa? The results of their research were presented in a written paper and at an oral poster session. The author of numerous papers they had read, Paul Olsen, attended the poster session and commented on each students work. Students found the work “strenuous” and many commented that they would have preferred a more traditional, lecture-based course. They would also have liked exposure to other sedimentary environments. In the future, I will limit this portion of the course to about half to two-thirds of the course and incorporate a broader range of environments.