Quaternary Geology at Colby College
at the Department of Geology,
Colby College

GE372 Students: click HERE to download a pollen count sheet in Microsoft Excel, for use in the lab project in the latter part of the semester. (Note that there is a "1" for an unnamed taxon in this spread sheet; this is solely to avoid an error message in the percent column, generated by dividing by zero. It should be deleted from your counts.)

Studies of Quaternary environments, those of roughly the last two million years of Earth history, are increasingly important as we struggle to understand the scale and rapidity of climatic and environmental changes in the modern world. How can we say, for example, that human activities are having major impacts on global climates if we can't say for sure what the natural rate of variability in those climate systems is?

Colby students are introduced to techniques in Quaternary Paleoecology through a course (GE372) that is open to all students meeting the prerequisites. In this course, students learn to identify some of the more important non-marine fossil groups that provide useful data to help us re-create what past environments must have been like, and from that information to approximate what past climatic parameters must have determined that biological environment.

The study of palynomorphs (pollen grains) in sediments is one way that past vegetation changes can be assessed. Above, Colby students are shown preparing to study and sample a river-bluff exposure of sediments along the Sandy River, about a half-hour drive north of the campus; these samples will provide the basis for subsequent lab work during the semester, in which they'll be evaluating the pre-European forest composition and environment with that of the present day at this same site.

At left are pollen grains of bog laurel, a common Sphagnum bog plant in central Maine. The plant grows in abundance in the Colby Marston Bog in Belgrade, about a half-hour drive west of the Colby campus, where Assistant Professor Bruce Rueger and student Kaatje van der Hoeven '95 are shown taking a sediment core in the photo below.

Other organic remains are frequently found in sediments that can also be very useful in interpreting past environments. Seeds, needles, and other plant fragments (called plant macrofossils as a group) can provide additional information about what plant species were present in the past; pollen can rarely be told beyond the generic level (e.g., pine, but not what kind of pine).

Insect remains can also be helpful. The beetle parts shown here were recovered from the sediments exposed in bluffs along the Sandy River, a short distance upstream from the site shown at the top of this page; they are about 2000 years old. They are fragments (front wings, called elytra) of a single leaf-eating beetle species that feeds almost exclusively on willows. Plants like willows and the bog laurel mentioned above, like all plants with showy flowers, are mostly or entirely insect-pollinated, and as a result the plants produce very little pollen. This frequently results in their being under-represented in the pollen floras recovered from sediments, and they may not show up in the plant macrofossil record either. Use of beetle remains such as those shown here can help to provide such additional details on vegetation, as well as many other aspects of past environments, that help geologists to achieve accurate reconstructions.

Five students at Colby have completed Senior Scholars* theses in Quaternary studies in recent years. These students, and their theses, which are bound and housed in Special Collections in Miller Library at Colby, were:
*The Senior Scholars program is an all-campus honors program, typically with 8-12 students enrolled annually. Students must show excellent academic records, be supported by a faculty mentor, and petition for admission to the program. Normally, students enroll for 6 semester hours of Senior Scholar credit in each semester and will take only two additional courses.

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Last modified 20 September, 2006.