Basic Facts About The Agate Fossil Beds National Monument

A US national monument situated in northwestern Nebraska, the Agate Fossil Beds National Monument protects a massive amount of well-preserved Miocene fossils. The area is also composed of grassy plains and a valley of the Niobrara River.


In the 1890s, scientists discovered the incredibly-well preserved bones of Miocene Epoch mammals, making the Agate Fossil Beds one of the most significant sites of its kind. The High Plains were once home to these ancient mammals and tribal nations like the Lakota Sioux before becoming inhabited by settlers moving west across America. The fossils found here date back to 20 to 16.3 million years ago, and are some of the best examples of Miocene mammals in existence today.

The site’s Agate Springs Ranch was originally owned by Captain James Cook, and is currently a working cattle ranch. The Agate Fossil Beds National Monument includes a museum that houses many artifacts from the Plains Indians. The national monument was officially established in 1997.


The main features of the park include the grassy plains, the Niobrara River valley, and the Carnegie Hill and University Hill fossils. There are a variety of plants and wildflowers found on the plains, some of which include prairie sandreed, blue grama, little bluestem, sunflowers, and western wallflowers.