TRACE FOSSILS ON CAMPUS: AN EXERCISE IN ENVIRONMENTAL INTERPRETATION FOR HISTORICAL GEOLOGY

Using macrofossils and trace fossils to interpret depositional environments is a subject commonly first presented to undergraduate geology students in Historical Geology (or similar courses). This subject is often presented in an abstract fashion, with numerous fossil lists associated with specific rock units. To make this sort of analysis more tangible students are assigned a project using trace fossil-bearing sandstone that has been used as flagstone for several patios on the campus of Concord University.

To complete the assignment students are divided into teams (2-4 students), and have one 3-hour lab period to complete the exercise. Each team must describe and sketch as many different types of trace fossils as they can (actual identification is not required). Most of the fossils are either trails or burrows, students are encouraged to define Trail #1, Trail #2, etc. Each team must construct a sketch map of each patio showing the positions of all the different types of trace fossils and make a population estimate (very rare, rare, uncommon, common, ubiquitous) for each fossil type.

Using their collected data they must make an interpretation of depositional environment. Students are provided with a standard trace fossil assemblage diagram, showing the different assemblages commonly associated with various sedimentary environments. The advantages of this exercise include the ability to take a field trip without leaving campus, allowing students to collect a suite of data and make a simple environmental interpretation. It also requires that students continue to develop more generalized observation and map sketching skills that they will need in later classes. Unfortunately, some of the fossils are best observed early or late in the day, when lower angle light makes the fossils more pronounced. Students completing the exercise in the middle of the day often miss the ubiquitous vertical burrows.