Formerly known as Menkenmaier Cave, Cow Cave, and Reub Long Cave, Fort Rock Cave is an archaeological site located near Fort Rock. In 1938, archaeologist Luther Cressman of the University of Oregon explored the cave and discovered several sandals made of sagebrush dating back more than 9,000 years—at the time, the oldest human artifacts found in North America. They were covered in volcanic ash from the eruption of Mt. Mazama, which formed Crater Lake. Fort Rock Cave was declared a National Historic Landmark in 1961; it is also a National Heritage site. Fort Rock Cave and the nearby land that is now Fort Rock State Natural Area were donated to the State Highway Commission in 1962 by ranchers Reuben and Norma Long, and subsequently transferred to OPRD from ODOT in 1996. In 2000, OPRD purchased an additional parcel of land around the cave from the Oregon Archaeological Conservancy for $12,000 with money donated by Cycle Oregon to the Oregon State Parks Trust, now the Oregon State Parks Foundation.