Wannagan Creek site

The Wannagan Creek site is a fossil site found just west of the South Unit of Theodore Roosevelt National Park of North Dakota, USA. The site is Paleocene in age, approximately 60 million years old. Paleontologists of the Science Museum of Minnesota have studied the site for nearly thirty years. The site is thought to represent a paleoenviroment of subtropical swampy lowland and forests. Preservation is excellent for both the flora and fauna of the site. Trace fossils of crocodilians and other vertebrates have also been discovered.

The topography of the site is that of a badland, due to the downcutting of the Little Missouri River. The rock units are likely sediments derived from the Laramide orogeny deposited in an ecosystem dominated by rivers, streams, ponds, lakes, and swamps.

The Wannagan Site is found in the upper portion of the Tongue River Formation (formerly Bullion Creek Formation). The rocks of this deposit, reaching a thickness of over 60 m, consist of yellow to tan, poorly lithified claystones, mudstones, and siltstones with a lesser amounts of interbedded fine-grained sandstones and lignite. The site is overlain by the Sentinel Butte Formation. This formation is generally gray to brown in color but is similar in lithology to the Tongue River. The Sentinel Butte is roughly 90 m thick. The between the two formations is roughly 6 m above the site. The Sentinel Butte contains an extensive stump-bearing petrified wood bed above the contact at the site.

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