The geology of the badlands area is significant not only for being a barrier to the pioneer wagon trains, but it is significant also for the fossils it contains. The majority of fossils found at Scotts Bluff National Monument are located in the Monument's badlands. Here the Orella Member of the Brule Formation is exposed. It consists of interbedded sandstone and siltstone layers that represent floodplain and channel deposits of ancient streams that flowed eastward from the uplifting Rocky Mountains. This is the oldest rock outcrop at the Monument. Fossils of horses, oreodonts (extinct, sheep-sized, four-toed mammals), prairie dogs, foxes, turtles, rodents, beavers, and cats have been found in the badlands. Some of the richest fossil-bearing strata in Nebraska are found here. The Monument's fossils have become type, or indicator, fossils for the Oligocene Epoch (40-25 million years before present) of the Cenozoic Era (65 million years to present). Most of these fossils were collected prior to the establishment of the Monument in 1919. Many other fossils could still exist within the Monument, so further paleontological research could be productive.
Fossil hunting in the badlands remains a real threat to the publicly owned paleontological resources of the Monument. Visitors must remember that the collection of natural features, including fossils, is strictly prohibited, and can result in a fine and/or imprisonment.