The fossilized tracks are believed to have been made during the Middle Jurassic Period, 160-180 million years b.p., on what was then a shore of the Sundance Sea.Theropod tracks are thought to be among those discovered, but evidence suggests that the tracks were made by a large, diverse group of dinosaurs. Due to a rarity of Middle Jurassic theropods, the species that made the tracks is currently unknown. The majority of the footprints are in the area dubbed "the ballroom".
Besides the trackways, a variety of fossils can be found, including belemnites, crinoids, and shrimp burrows.
The tracksite is in a limestone layer in the lower part of the Sundance Formation. Its discovery was somewhat surprising, since the Sundance was historically considered to be marine in nature. Indeed, the layer just above the tracksite contains abundant marine fossils including numerous Gryphaea nebrascensis, indicating that later in the Jurassic it was once again submerged.