People first came to Scotland after the last ice age around 10,000 years ago. Mesolithic hunters and gatherers lived and moved around the area where they would catch fish and sea mammals as well as animals such as deer, and collect plant food and shellfish. These people may have affected their environment, for instance by burning woods to create more grassland, but they have left no visible monuments. They are recognized by their characteristic tiny chipped flints, used to arm arrowheads and knives. Examples have been found at Oliclett, the earliest examples from Caithness that date to about 6000 BC.