Judith River Formation

In 1855, geologist Ferdinand V. Hayden explored the upper Missouri River for the United States Geological Service. At that time, the area was the hunting ground of the Lakota, Blackfeet, Atsina, and River Crow Indians. A lone white man in Indian Country was often fair game to the tribes, but Hayden’s passion for rocks and fossils earned him the name “He Who Picks Up Stones While Running” and a reputation for madness. The Indians left him alone. Hayden explored what would later become known as the Judith River Formation, a large area of sedimentary materials deposited in the lowland areas bordering the Colorado Sea during the Late Cretaceous Period 78 to 74 million years ago. During his exploration near the mouth of the Judith River, Hayden collected many fossilized teeth, bones, and shells from the Judith River Formation. He took them to anatomy Professor Joseph Leidy in Philadelphia for identification, who classified the teeth as belonging to a new species of hadrosaur. The teeth and bones were the first dinosaur fossils found in North America. Hayden’s discovery drew paleontologists to Montana in search of dinosaur fossils and to the Judith River Formation making it a significant paleontological destination.