From rift to drift then back again—undergraduate majors head for the hills
by Shanan Peters
Although a long history of past field trips have left many GeoBadgers in the know, few are aware of the fact that Oklahoma boasts three, yes THREE, mountain ranges: the western Wichitas, the eastern Ouachitas, and the mighty Arbuckles in between. During Spring Break 2009 (March 14-22), thirteen more undergraduate GeoBadgers got to know these OK ranges and the excellent geology they expose.
Led by Shanan Peters, fly-boy Alan Carroll, and a fearless, but all-too-patient TA Chloë Bonamici, the crew left Madison, caravan style. After a missed turn by the cargo van while still on Madison’s beltline, we reached the edge of Oklahoma without further incident. A fuel-up and cultural experience at Okie Burger in the little burb of Miami left everyone ready to crash at a nearby state park in preparation for the next day’s much shorter drive.
After an early reveille and Shanan’s call to identify the rocks that you slept on (it’s kind of an unspoken requirement on the field trips), we loaded ‘em up and headed to the Wichitas. Holding our breath as we passed over the fault that bounds the southern edge of the deep Anadarko Basin, our first goal was to find scrappy exposures of the contact between the Meers Quartzite and the Wichita Granite Group. Although we could pin down the area of the contact fairly precisely, the only good exposures were of each unit individually. After giving up on that, we climbed Mt. Scott, made up of the Cambrian Mount Scott Granite, and scanned the horizon for Alan’s self-built plane. Having met up with Alan, we returned to camp and planned our trek through the igneous rocks that record the rifting of the continent.
Another day or two spent hiking on a layered mafic intrusion at the Peterson Ranch and the volcanics and sediments of the Kimball Ranch, we were ready to head upward and into the Paleozoic, to the drift phase of the trip. The trek to the Arbuckles wasn’t without trouble.
Our trusty cargo van “Garnet” decided to become untrustworthy and broke down along the road. But guess what? It did so right beside a beautiful Permian outcrop, one of the only exposures for miles! This was, ironically, a very positive turning point for the trip. Shanan, Chloë, Boomer Bain, Brian Boston, Angeline Catena, Aaron Firnstahl, Jordan Gonnering, Ben Gottsacker, Sam Hayes, Reba Heiden, Dylan Loss, Hana Millen, Lynsey Spaeth, and Carolyn Streiff all bonded over the experience by geologizing, frisbee throwing, and other shenanigans. Jim Senn and Alan were absent from that experience for aerial reasons.
The rest of the trip was excellent. We spent time on Paleozoic carbonates deposited on the passive margin and then watched the siliciclastics and too-many (according to some) turbidites of the Ouachitas give testament to the collision of Laurentia and Gondwanaland. The Cretaceous coastal plain seds told us the tale of the final rift-to-drift phase and, our story complete, we headed north.
To see the trip virtually in Google Earth, visit http://strata.geology.wisc.edu/home/geo737.html
Originally published in The Outcrop for 2009, UW-Madison Department of Geoscience, p. 18.