David Harbor

Landscape evolution at the margin of the Basin and Range

Streams erode new basins in extensional mountain ranges where tectonic asymmetry facilitates divide migration. Ranges in the northern Basin and Range of the United States form a space-for-time series that illustrates stream incision and divide migration following footwall uplift, accelerating basin growth, and changes in the amount and direction of volume loss. During basin expansion, stream erosion exceeds hillslope retreat, which elevates summit plateaus.

Field-based Instruction as Part of a Balanced Geoscience Curriculum at Washington and Lee University

Traditionally at Washington and Lee University teaching in the field has been the core of our geology curriculum. We emphasize fieldwork at all levels of our instruction from the field-based introductory courses to our senior theses. We are fortunate to be located in a geologically diverse location (in the Valley and Ridge of Virginia and within minutes of the Blue Ridge Mountains). The close proximity of geologic variety allows us to spend nearly every class or laboratory period outside. We view fieldwork, however, as just the beginning of geoscience education. A crucial aspect of field geology is making observations and synthesizing the data collected. It is equally important for students to have well-developed skills in field methods, in analytical techniques, in computation and modeling, and in synthesis and presentation. To emphasize all of these aspects, our coursework is largely focused on emulating the process of research. Because we have had such a strong field emphasis, we are striving to strike a balance in our curriculum. We will present 3 examples of integrated exercises in our geology courses (including introductory geology, sedimentary geology, and geochemistry).

Reading Virginia's Paleoclimate From The Geochemistry And Sedimentology Of Clastic Cave Sediments

Clastic sediments in Bathers Cave, Virginia, are divided into distinct packages that reflect changes in water velocity, sediment source, surficial weathering conditions, and the cave depositional setting that are a function of Quaternary climate change. These packages are found in the same stratigraphic order at various levels on ledges within passages of elliptical cross section in the upper part of the cave system. Sediment extractions performed on separate fractions from each layer indicate changes in oxide mineralogy and clay mineralogy through the sedimentary sequence. Additional samples from a nearby flood plain, a terrace soil, and a sinkhole pond also show mineralogical and geochemical changes. Goethite is abundant in the lower layers of the cave sequence, while the upper layers have mostly ferrihydrite and abundant kaolinite.

Testing the Waters: Can You Involove Community Action in your College Curriculum?

The Maury River Alliance (MRA) was developed at Washington and Lee University (W&L) as a cooperative program involving local colleges, high schools, government agencies, and conservation groups. The MRA is a mostly volunteer organization (42 volunteers currently) that samples the Maury River and its tributaries, including the urban stream flowing through campus. Its purpose is both to serve the community and to provide students and faculty with research opportunities. We are addressing the connection between land use and water quality with a creative merging of technical, social and educational aspects of local watershed management. During the first year and a half of the program we have developed a baseline water quality for low flow conditions. We have observed that water quality degrades as the river passes through the county, especially with the addition of urban and agricultural tributaries. Nutrients and bacteria are of greatest concern, with storm water high in heavy metal concentrations. In addition to exposing students to a community effort, the ultimate interest for the faculty is to focus on the scientific results. The proximity of the study site to the school and the large numbers of volunteers involved in the project contribute to the success of the project. These numbers facilitate the collection of large data sets and a plethora of research possibilities yet also present a challenge of organization and management. While professors focus on data analysis, students (and now a recent graduate as director) have acted as managers of the program, thus furthering the educational opportunities.