The Bighorn Basin is a large intermontane basin in the Rocky
Mountain foreland (Blackstone, 1986). The Bighorn Basin includes
parts of Big Horn, Park, Washakie, and Hot Springs Counties.
Like the other major sedimentary basins of Wyoming, such as the
Shirley Basin, the Laramie Basin, and the Powder River Basin,
the Big Horn Basin is bound by significant mountain uplifts:
the Beartooth Mountains on the Northwest, the Pryor Mountains
to the North, the Bighorn Mountains on the East, and the Owl
Creek Mountains on the South (Heasler and Hinckley, 1985). The
basin is composed of approximately 10,000 square miles of dominantly
Cretaceous rocks in addition to localized outcrops of Triassic,
Jurassic, and Tertiary stratigraphy. |
Prior to the Laramide orogenic event, the Bighorn Basin was not
a sedimentary or structural basin. Rather, the Paleozoic and
Mesozoic formations were deposited in a setting of a large platform
area that saw repeated transgressions and regressions of the
epicontinental seas. Of interest to the study of the fossil material
on the Warm Springs Ranch are Mesozoic
strata, in particular, the formations deposited from the
Triassic through the Cretaceous. |