FLAT ROCKS, ZERO OUTCROP: INTRODUCING A LARGE, LECTURE-STYLE, INTRO-LEVEL EARTH SCIENCE COURSE TO ACTUAL GEOLOGICAL MAPPING IN A GEOLOGICALLY WANTING AREA

Many an earth science department is located in an area with extremely limited local rock outcrops, often of units with little to no structural complexity. Travel to geologically richer areas is often prohibitive due to budgetary concerns. Furthermore, large lecture-style introductory courses do not lend themselves easily to individual-based field exercises due to logistical constraints. As a result, few intro-level students ever learn and apply actual geological mapping skills in the field. This is unfortunate as field-mapping is not only fundamental to various branches of the earth sciences but also provides ample means to teach about hypothesis testing, inference making, and scientific uncertainty.

The exercise presented here is rooted in traditional laboratory approaches to geological maps and structures. However, whereas these are typically limited to diagrams or table top “outcrops”, often consisting of boards, rock slabs, or books placed at various dip angles, the approach here significantly expands the scale of the exercise to closely mimic the real world. 60 “outcrop” stations were constructed using wooden boards. Each station models the strike and dip of a virtual sedimentary layer. Stations are constructed to be accurate to within one degree and are collapsible for easy storage. Each station also contains a matching rock sample to be identified and described by the students. These stations are placed, anchored by stakes, across the university campus (~0.25 mi²) to form a particular geological structure (i.e. a structural dome). Students use hand-held GPS units to map the station’s distributions relative to one another, and a compass and protractor to measure their strike and dip. Using this information, students construct a geological map and cross-section.

Students work in pairs and spend 2-3 hours in the field, depending on the number of stations analyzed. This allows for a total of ~220 students to participate in the exercise throughout the course of a week. Students are briefed before the exercise using an online presentation that uses custom-made animations to introduce geologic mapping and to demonstrate how to measure strike and dip, infer unit contacts, and construct geological cross-sections. A post-exercise survey was used to collect data on the effectiveness of the exercise.