Comprehending the Cretaceous of the Western Interior Seaway
by Amalia Doebbert
At the beginning of June, a group of eight, led by Clay Kelly and Eric Williams embarked on a tour of rocks left behind by the Western Interior Cretaceous Seaway. Over the course of 10 days, we covered ~3000 freeway miles, camped in six different places, and looked at rocks in three states. At our first geological stops, we visited the Niobrara Formation at Castle Rock and Monument Rocks in Kansas (there IS topography there!). Leaving the plains behind us, we stopped to see carbonate mounds at Tepee Buttes near Colorado Springs, where we had our (thankfully) only rattlesnake encounter.
While in Colorado, we also checked out the Cenomanian-Turonian Boundary global stratotype section near Pueblo. An overnight stop at Black Canyon of the Gunnison provided us with spectacular views of Precambrian basement in one of the country’s best-hidden national parks, followed by a drive through the Mesozoic section at Colorado National Monument and moving on to our final destination in the Book Cliffs of Utah.
Having finally arrived, we set up camp at a wonderfully isolated spot on Blue Flat near Emery and set out to explore the classic outcrops of the Ferron Sandstone. Highlights in the Book Cliffs included rotated slump blocks and a hard hike at Muddy Creek, a beautifully preserved transgressive succession at Gentile Wash, and more hummocky cross-stratification than you can shake a stick at.
Discussions were focused around accommodation, sediment supply, and stratigraphic architecture in distributary systems. A brief visit to the prehistoric museum in Price, an ammonite-hunting stop in the Mancos Shale, and a short foray back into the Jurassic at an unconformity in the Morrison Formation were also part of our Utah adventures.
A night spent at the Little Grand Canyon (think gorgeous canyon, no people) and an impressive panel of petroglyphs and pictographs at Buckhorn Wash wrapped up our time in Utah. A great Mexican dinner in Gunnison, Colorado, provided a perfect conclusion to a great trip before one last night sleeping outdoors and the long drive home.
Originally published in The Outcrop for 2010, UW-Madison Department of Geoscience, p. 17.