Wyoming’s Bridger Basin Badlands

November 01, 2016

Wyoset88c_8oct16 (2)

Photographer: Ray Boren
Summary Author: Ray Boren

Autumn-tinted cottonwood trees cast goblin-like shadows on a high bluff’s sheer escarpment just before sunset on Oct. 8, 2016, near the community of Mountain View in southwestern Wyoming’s geologically and paleontologically significant Bridger Basin badlands. Besides their colorful topography, the Bridger Basin and the broader, stratified Bridger Formation (both named for 19th-century American fur trapper, explorer and trader Jim Bridger) are significant for the diverse remains of animals and plants found in their sedimentary beds, including limestone, mudstone, claystone, and volcanic ash.

The fossils help outline the evolution of modern mammalian orders in the middle Eocene Epoch, following the dinosaur extinction 65 million years ago. As the Rocky Mountains rose during North America’s mountain-building Laramide orogeny, sediments began to accumulate in intervening basins. Erosion, ash from volcanoes near and far, and organic matter, including plants (such as tree trunks), and bodies of animals (such as insects, fish, birds and turtles) began to accumulate. In the Bridger Formation they've been preserved as fossils in layer upon layer for millions of years.

In the 1860s, trapper John (Uncle Jack) Robertson found what he thought to be a petrified grizzly bear (perhaps a brontothere skull), and explorer-geologists like Ferdinand Vandeveer Hayden began collecting, reporting and distributing fossils. The Bridger Formation became a focus of rival paleontologists Othniel Charles Marsh and Edward Drinker Cope and their collecting expeditions, which resulted in the acrimonious yet scientifically productive Bone Wars and the related fossil hunts of the 1870s and beyond. [Revised November 2017]

Photo Details: Camera Model: NIKON D3200; Lens: AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED; Focal Length: 230mm (35mm equivalent: 345mm); Aperture: ƒ/10.0; Exposure Time: 0.0031 s (1/320); ISO equiv: 400.