The earliest traces of humans in Schwyz are from the Upper Paleolithic and Early Mesolithic or about 12,500 BC. An excavation of the karst caves in the valley of the Muota river ("Muotatal") revealed numerous sites, some dating back to the Younger Dryas period (c. 10,000 BC). The alpine meadows at Bödmeren, Twärenen and Silberen were stone age hunter-gatherer camps. Ibex and red deer bones along with charcoal indicate that the animals were butchered and cooked in these camps. In 2009 the first stone age tool in the canton, a stone drill, was discovered.