Excavations from cave sites, such as Wookey Hole and Creswell Crags, show butchered deer bones and other signs of human activity, dating to c. 16,000 BP. This is thought to be a temporary reoccupation, after the human population deserted England and northeastern Ireland for warmer climates during the glacial period. In the post-glacial Mesolithic period (c. 9000–6500 BCE) humans returned in large numbers, using a land bridge across the English Channel. In the rising temperatures England was blanketed with woodlands, with herds of reindeer and wild horse replaced by elk, red deer, roe deer, wild boar and wild cattle (aurochs). Mesolithic Britons established semi-permanent settlements, such as Star Carr, where a stag headdress is thought to be evidence of stag hunts or shamanism. There are also bones from early domesticated dogs. Barbed points of bone and antler found north and east of Broxbourne are thought to have been used for harpoons, lances or spears and arrowheads.