The Mesolithic Age refers to the period between the Palaeolithic Age and the Neolithic Age. Archaeologically, these ages are relative. Geologically, the Mesolithic Age covers the Late Pleistocene and Early Holocene, and it extends from 10,000 to 20,000 years ago. The raw materials for the microliths from this period are mainly agate, chert, quartz (vein quartz) and chalcedony. Tools include pointed tools, scrapers, end cutters, stone knives, carving tools, stone cores, stone drills and stone clusters. Composite tools, arrows and bows were also used. The Mesolithic Age was a transitional period. Microliths have been found in the Late Palaeolithic Zhiyu and Xujiayao cultural relic sites.