THE CASE OF THE MYSTERY CONGLOMERATE: SCIENTIFIC DISCOVERIES ON FIELD TRIPS

My type of field trip is not a canned field trip where I stand by the road and give a lecture on an outcrop of rocks. I want the students to learn the scientific process by doing real geology themselves. Students make observations in field books, test hypotheses, investigate the literature, and write mock grant proposals and detailed field trip reports. The field trips and reports are the key time in the semester when the students really become engaged with the course.

I teach Stratigraphy at California State University, Stanislaus, an upper division course for geology majors. During spring semester 2004, our first field trip was to Del Puerto Canyon, near Patterson in Central California. The objective of the trip was to teach the students how to measure and describe stratigraphic sections and how to interpret depositional environments. During this field trip, we discovered a 100-meter thick deposit of sandstones and conglomerates. Student opinions on the depositional environments ranged wildly, from a volcanic-related mudflow, a submarine canyon debris flow triggered by a canyon failure, to an alluvial fan! Lively class discussion after the field trip prompted me to add additional assignments. In order to focus their ideas on how the deposit formed, I had them write mock GSA grant proposals. They proposed investigations that would test their hypotheses on the depositional environments using appropriate sedimentological and stratigraphic methods. However, during their grant and report writing work, the students could find no mention of this deposit in the literature! Several students from class formed a research group to further the investigation; they have made additional field trips, have searched the literature, and plan to continue their research next year. Discovering the ‘mystery conglomerate’ showed the students, first hand, how exciting and rewarding making new scientific discoveries can be. For most of the students, this was their first scientific discovery, and their excitement made them more engaged in the class and in geology.