When the glaciers finally retreated around 10,000 BC, a bleak wilderness slowly became covered in forest and people evolved new technologies to deal with their surroundings. The Mesolithic or Middle Stone Age describes this period when hafted axes and 'composite' tools like harpoons and spears made from several tiny razor-sharp microliths appear for the first time. These sophisticated hunters and fishers used fire and axes to make clearings in the forest and developed complex tools and equipment, though rarely does anything other than flint or stone survive.