Originally the Agate Springs Ranch, a working cattle ranch, was owned by Capt. James Cook. The monument's museum collection also contains more than 500 artifacts from the Cook Collection of Plains Indians artifacts.
The national monument was authorized on June 5, 1965, but was not established until June 14, 1997. The Harold J. Cook Homestead (Bone Cabin Complex) was listed on the National Register of Historic Places in 1977.[4] Agate Fossil Beds is maintained by the National Park Service.[5]
Paleontology
The site is best known for a large number of well-preserved Miocenefossils, many of which were found at dig sites on Carnegie and University Hills. Fossils from the Harrison Formation and Anderson Ranch Formation, which date to the Arikareean in the North American land mammal classification, about 20 to 16.3 million years ago, are among some of the best specimens of Miocene mammals.[6]