When he excavated Gypsum Cave (Nevada, USA) in the 1930s, archeologist Mark Harrington concluded that humans and Late Pleistocene animals used the cave around the same time. It was an astounding theory, because it would have made the cave, which is in the Frenchman Mountains east of Las Vegas, one of the oldest human habitation sites in North America. More recently technology indicates the humans came much later than Harrington supposed, but the cave is still an important archeological and paleontological site.
     Amy Gilreath of Far West Anthropological Research Group recently made a speech about the research she and colleague D. Craig Young carried out in 2004. Gypsum Cave, divided into several rooms, is 300 feet long and 120 feet wide. The front part of the cave contained rich evidence of being occupied by humans and prehistoric animals. Harrington spent about a year excavating the cave in 1930-31. The archeologist mapped the strata of the cave and found various ages of occupation by people and animals. One of the prominent features of the cave is a thick layer of ground sloth dung. Harrington found claws and other remains of the ground sloth, as well as evidence of prehistoric horses and camels. Gilreath said the material found in the cave was remarkably well preserved.
     Harrington's surprise discovery was darts and other human artifacts below the ground sloth layer. Since the Shasta ground sloth became extinct about 9,000 years ago, the evidence seemed to indicate human habitation before that, But Gilreath said when radiocarbon dating technology became available, tests showed the human evidence was not much older than 4,000 years. When she and her colleagues were studying the cave, they noticed a number of packrats scurrying through the jumbled rock, and concluded the rodents moved material from the upper layers to lower layers.
     "Harrington found an extraordinary amount of perishable material," she said, such as cordage, wood, cane and fibers. The dry climate preserved the archeological material, as well as the material from the Pleistocene age, she said. Gilreath said research throughout the Great Basin region shows the climate was much harsher and drier before 4,000 years ago. Then the climate moderated, and human habitation increased in the Middle Archaic age, from 2,250 to 4,000 years ago. "Gympsum Cave fits that profile," she said.
     Gilreath said the process has been started to have the cave listed on the National Register of Historic Places. "It has tremendous value to native Americans, archeologists, paleontologists and geologists," she said. Because of the unstable geology, the BLM strongly recommends people do not go into the cave, she said.

Source: DVT Online (26 May 2009)