He had investigated its Pleistocene-era deposits, documented evidence of the pygmy mammoths whose remains appeared in the island’s ancient sediments, and compiled a growing record of the island’s human prehistory.

The island had been occupied by Native people long before Europeans arrived, and Orr was assembling evidence of that long history.

The canyon where he found the bones in 1959 was called Arlington Canyon — a deep arroyo cutting through the island’s sedimentary layers in its western interior.

The canyon is fed by Arlington Springs, a water source that had supported life on the island across geological time.

Streams running through the canyon had, over millennia, deposited layered sediments recording climate changes, vegetation changes, and the biological history of the island.