The earliest known evidence of human presence in the area dates back to the Mesolithic period. The most important remaining settlement of this period is that at Star Carr, where archaeologists have found evidence of a permanent house 10,500 years ago on the shore of what was then a shallow lake, as well as "a wooden platform extending 18-20 feet over the surface of the lake itself near Scarborough, where, due to waterlogged conditions, a considerable quantity of organic remains as well as flint tools, have survived. This is Britain’s best-known Mesolithic site. The site, on the eastern shores of glacial Lake Pickering, was surrounded by birch trees, some of which had been cleared and used to construct a rough platform of branches and brushwood. Lumps of turf and stones had been thrown on top of this construction to make a village site. The site was probably visited from time to time by about four or five families who were engaged in hunting, fishing and gathering wild plants as well as manufacturing tools and weapons and working skins for clothes.