Student Research Projects

Determining geologic formations by looking at riverbed sediments

Student Rebecca Hyman, '16
Faculty Mentor(s)
Department Earth and Environmental Sciences
Course Earth and Environmental Science 489: Research in the Natural Sciences


The Piedmont region of Virginia is a very difficult region to study due to the fact that it consists of a complex mixture of igneous and metamorphic rocks and there is hardly any exposure of underlying rocks in the region due to thick soils and vegetation. This study is part of a larger project to find out whether we can determine and characterize the geologic bed underneath by looking at the sediments in riverbeds. In this portion of the study I used ArcGIS to identify areas where a watershed lies completely within one geologic formation. Using published online data files, I found two areas that met that criteria. Most of the watersheds do not meet the criteria and so I used two separate methods to find my sampling locations. First, I used the querying method to select the criteria I wanted to examine. Through selecting by location and selecting various constituents, I found only two locations that fit. The next method I used was through the spatial analyst hydrology tools. Following the steps for delineating a stream network and watershed boundaries from a digital elevation model, I chose one stream to focus on, and determined a prime location for sampling. I mapped out the locations in order for sample collection by determining where a road intersects the stream of interest. Once sediments are collected, they will be taken back to the lab for further inspection to determine the composition of the collected sediment. We hope ultimately use sediment collected in this way to identify rocks underneath in certain areas anywhere in the Piedmont.