• The Agate Fossil Hills where mammal fossils were excavated in the early 1900's

    Agate Fossil Beds

    National Monument Nebraska

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Agate Bonebed

A worker building a crate around a bonebed slab in the early 1900's.

This worker is building a crate around an Agate Bonebed slab in the early 1900's.

Most of the fossils in the Agate Fossil Beds were found in a bonebed, some 2 ½ to 4 feet thick. Fossils from Menoceras as well as Dinohyus and Morophus were found together in the bonebed. This puzzle presented a question of how to take the fossils out of the fossil hills. Following is an explanation of that process.

The first stage of the operation was to cut down the overlying rock to about two feet above the bone layer. This is done by the methods of rock-cutting with drills, dynamite, and blasting powder, heavy picks and a team of horses and scraper to remove the debris.

Next the more careful work of removing the sediment down to the bone layer itself began. Different tools were used here: light hand picks, awls and whisks followed by soft brushes to clean dirt away as the bones were exposed. The bone surfaces were soaked with thinned shellac varnish, especially on parts that were cracked or shattered. When a large area had been exposed, the bones were studied and a decision made on how to take them out. If some of the lesser found Moropus or Dinohyus bones were lying with a mass of Menoceras bones, the latter may have been sacrificed in order to channel around the more valuable bones. The main intent was to reduce the size of the block of bonebed to a size that could be easily handled and transported; not over four or five feet square and one to two feet thick.

After a narrow channel had been cut all around the block through the bone layer, it was undercut a bit and then bandaged. Several coats of shellac were applied and thoroughly dried in the hot sun before the bandaging began. Strips of burlap dipped in plaster of Paris were applied to the surface and then kneaded down to stick to the surface. The strips were laid parallel until the entire surface was covered, then a second set of strips were laid at right angles to the first. This formed a rigid and tough casing over the block and around the edges.

The block was further undercut sometimes using barbed wire as a cutting tool until the block was loose and could be carefully turned over. The underside was trimmed smooth, soaked with shellac and bandaged. When thoroughly dry, the block was boxed with lumber brought to the site for that purpose. Using skids or levers the block was lifted onto a wagon and hauled to the railroad station. Heavy blocks called for the use of a tripod with differential pulley or ropes and chains.

This bonebed slab is on display at Agate Fossil Beds.

This slab of the Agate Bonebed is on display in the visitor center.

When the bone slab arrived at whichever museum or university the field crew worked for, the slab was opened in their lab and the fossils exposed. Many bone slabs were opened in this way and are still on display. Some of the institutions with slabs of Agate Fossils are: The Trailside Museum at Fort Robinson, NE; Museum of Geology, South Dakota School of Mines and Technology in Rapid City, SD; The Geological Museum at the University of Wyoming in Laramie, WY; University of Nebraska State Museum in Lincoln, NE; Field Museum of Natural History in Chicago, IL; The University of Michigan Exhibit Museum in Ann Arbor, MI; Carnegie Museum in Pittsburgh, PA; The American Museum of Natural History in New York, NY and the Museum of Comparative Zoology in Cambridge, MS.

Did You Know?

small Stenomylus camel

A very small camel, the Stenomylus camel, was found near the Agate Fossil Hills. This camel was about two feet tall at maturity. Although the quarry is not accessible, displays about this fragile-looking animal are available in the visitor center. More...