Through My Eyes, In My Words:

Coral Reefs and Caves: The Geology of the Bahamas

Taught by Dru Germanoski, Dr. Ervin R. VanArtsdalen ’35 Professor of Geology and Environmental Geosciences, and Kathryn A. Schubel, assistant professor of geology and environmental geosciences

Michael Werner of Neenah, Wis., is a Marquis Scholar double majoring in biology and geology. A participant in the McKelvy House Scholars program and recipient of the Nalven Summer Scholarship, he researched the effect of RANTES on T-cell proliferation as an EXCEL Scholar working with Robert I. Kurt, assistant professor of biology. He plays trumpet in the Jazz Ensemble and Brass Ensemble and rows for Lafayette crew.

By Michael Werner’07

A student of any background would find this interim course very exciting. We spent two weeks in the field studying the geology of two fairly economically undeveloped Bahamian islands, San Salvador and Andros. On each island we stayed at rustic field station that housed groups of college undergraduates, graduate students, and professional researchers. These field stations exist because understanding the geology and ecology of the Bahamas is very important for the inhabitants. The people of the Bahamas depend on the brilliantly colored coral reefs and healthy fish populations to attract tourists and support local fisheries.

These islands are geologic trophies in that each is essentially an outdoor classroom with unique features, some of which can only be found a few places in the world. Our first week was on San Salvador, one of the smallest islands. After learning the basic concepts behind comparative sedimentology, we visited the island’s many different geologic subenvironments. We profiled various beach faces, climbed ancient sand dunes, snorkeled coral reefs, and explored intricate cave systems.

We spent the second week on Andros, the largest Bahamian island. Although part of the same geologic system, it was surprisingly different from San Salvador. Whereas the interior of San Salvador was uninhabited and consisted only of shrubs, the interior of Andros was rich in wildlife, pine forests, and Bahamian culture. In this setting, we continued our studies of coral reefs and carbonate platforms. We also learned about basic hydrology, resource management, and blue holes. Blue holes are large, deep, almost perfectly circular lakes that continue to mystify the native Bahamians. During periods of glaciation, sea level can drop to 400 feet below its current level. Then, as rain water percolates downward, it dissolves the limestone bedrock. When sea level rises to its current elevation, the holes are flooded.

As both a geology and biology major, I found this course especially fulfilling because of the close relationship between geochemical and biological processes that build carbonate platforms, including coral reefs and muddy tidal flats. I am always fascinated by the way biology and geology affect each other in many geologic environments. The Bahamian platform is a perfect example. In shallow water, a small plant-like organism called Penicillus precipitates calcium carbonate to stiffen itself against the continuous wave action above. When this green alga dies, it leaves behind mud-sized sediments consisting of calcium carbonate (the major mineral in limestone). For the most part, it is the accumulation of these sediments that have produced an entire chain of limestone islands!
One of the most memorable experiences of the trip was hiring boats to transport us to a tidal flat on the western side of the island. Here, our noble professors led us unknowingly into a large field of pure calcium carbonate mud that was 2-3 feet deep in some parts. Inevitiably, the situation escalated into class-wide mud fight that did not discriminate student from professor. On Andros we also had the privilege of visiting a few villages. We talked to local artists and even a renowned medicine woman.

The Bahamas is a unique geologic setting. There are few places in the world where one can study both ancient and modern depositional environments. The dominant concept of the sedimentary geology is that the present is the key to the past. On many occasions, we would visit a modern environment, like a sand dune, then walk a few feet, look at a rock formation, and see its ancient analogue. This is a concept that can only be understood so much through lectures. Going out in the field and actually seeing the concept at work adds a new level of understanding to geology.