Introductory Geology Field trip to Arbuckle Mountains, OK:John Wickham, Department of Earth & Environmental Sciences, University of Texas at Arlington
The audience is undergraduate, non-science majors taking an introductory Geology course for their university science requirement.
Arbuckle Mountains, near Interstate 35 north of Ardmore, OK.
The field trip is part of the required lab associated with an introductory geology course for undergraduate students. Students are familiar with rocks and minerals, but not much else. We have had people in wheelchairs on the trip, but that is not generally recommended. All stops have public access. One stop along the interstate requires parking on the dirt shoulder; this may be problematic during wet weather. The highway patrol generally does not bother people parked well off the interstate, but we limit the number of cars to six to avoid problems.
Goals include reinforcing concepts or introducing new ones such as: identification of rocks and minerals in the field; grouping rocks into formations; structural strike and dip; constructing qualitative cross sections; recognizing simple structures such as anticlines, synclines and faults; reading topographic maps; reading geologic maps; recognizing and interpreting angular unconformities; recognizing river features and processes such as flood plains, point bars, cut banks, oxbow lakes and cutoffs; understanding groundwater, water table and interaction with rivers.
The road cuts and outcrops near Interstate 35 North of Ardmore, OK, have been used by universities within driving distance ever since the interstate was completed in 1970. The outcrops illustrate most of the basic geological concepts related to structure and stratigraphy, and they match the goals of an introductory course. However, no igneous or metamorphic rocks are visible along this particular transect. The Washita River, showing most of the geomorphic features of a typical meandering stream, is an added bonus.
The only pedagogical decision was whether to make the field trip a "show and tell" or an active learning experience. In choosing the latter, the field trip was designed around questions about the outcrop and maps, concluding with a qualitative constructioin of a cross section using data collected from outcrops.
Notes and Tips:
All localities have public access. Two of the stops are on interstate roadcuts, but there is plenty of room on the dirt shoulder for groups of up to 40 people to be safely away from the traffic (except in the unlikely event of an out-of-control vehicle completely off the paved shoulder). Only one interstate stop requires parking along the dirt shoulder so the number of vehicles should be limited to 5 or 6. However there is overlook parking about 1/2 mile away if people want to be ultra-safe and walk. The other interstate stop has overlook parking. While the interstate stops are geologic classics and should not be missed, the highway noise can drown out any discussion among larger groups. This can be overcome by using a bull horn and having a student/instructor ratio around 15.
The interstate roadcuts illustrate an angular unconformity and an outcrop sized faulted anticline-syncline. I take along a whiteboard and have students draw the outcrop; this immediately gets their attention.
At each outcrop, I have students estimate dip and dip direction. I bring along a brunton to see who makes the best guess which usually piques their interest.
Assessment and Evaluation:
Assessment is based on student evaluations of the lab and field trip. Many say the field trip was the best part of the course.
Materials and Handouts:
Materials used in preparation for the trip include those in the references plus my own specific observations at the outcrops.
Equipment that I use on the field trip includes a brunton compass; acid; whiteboard to make drawings of the outcrop; and the Geological Map of the Arbuckle Mountains (Ham and McKinley in the references).
Fay, Robert, 1989, Geology of the Arbuckle Mountains along Interstate 35, Carter and Murray Counties, Oklahoma. Oklahoma Geologycal Survey Guidebook 26.
Wickham, John & Rodger Dennison, 1978, Structural Style of the Arbuckle Region. Geological Society of American, Souther Central Section Field Trip #3.
Ham, William, 1973, Regional Geology of the Arbuckle Mountains, Oklahoma. Reprinted, 1978, as Oklahome Geological Survey Special Publication 73-3.
Ham, William and Myron McKinley, 1954, Geological Map and Sections of the Arbuckle Mountains, Oklahoma. Revised by Kenneth Johnson, 1990, as Oklahoma Geological Survey Map GM-31.
Fay, Robert, 1981, The Southwest Davis Zinc Field, with Geologic Map of Southwest Davis Zinc Field, Arbuckle Mountains, Oklahoma, compiled by Robert Fay. Oklahoma Geological Survey Map GM-20