Agate Fossil Beds National Monument

Agate Fossil Beds National Monument, national monument authorized in 1965. Located in northwestern Nebraska, the monument preserves fossil beds in the hills above the Niobrara River. The fossils, enclosed in sedimentary rock, are about 19 million years old and are from mammals that lived during the Miocene Epoch. The fossils include a previously unknown species of rhinoceros; the dinohyus, a pig-like creature; and the moropus, a large animal with a horselike head. The Fossil Hills Trail goes to Carnegie and University Hills, where most of the fossils are quarried. The Daemonelix Trail leads to the monument where exposed fossils can be seen. The park also includes Agate Springs Ranch, once owned by rancher James Cook. In the 1870s Cook was the first person to find the fossils, and he supported the study of fossils here. The Cook Collection of Indian Artifacts features items associated with Agate Springs Ranch visitors from 1890 to 1940, including Chief Red Cloud, a leader of the Oglala Sioux during the late 1800s. Administered by the National Park Service. Area, 1,236 hectares (3,055 acres).