Quarry A

Quarry A, behind this ridge at Agate, was the first scientific excavation conducted there. In 1904, Olaf Peterson of the Carnegie Museum of Pittsburgh found fossil bones of many rhinoceroses, most of them from the large, heavy-bodied Diceratherium niobrarense. A volcanic ash layer called the Agate Ash, found just above Quarry A, has been dated at 21.9 million years and provides evidence of the approximate age of the fossils. Quarry A is older than the waterhole bonebed at University and Carnegie Hills by an unknown interval, probably more than one million years. Diceratherium niobrarense was the most commonly found animal in Quarry A, while the smaller rhinoceros Menoceras was rare; in the main Agate bonebed, the opposite was true.

Nebraska · United States