Sequences of preceramic cultures or well-defined artifact assemblages are now known for the Ecuadorian highlands, the central and southern highlands of Peru, the entire coast of Peru, western and southwestern Bolivia, northern Chile, highland Argentina, Patagonia, and Tierra del Fuego. The known lithic industries of the area can be organized into a scheme of five periods, based on the long sequence at Lauricocha in the central Peruvian highlands and defined by the occurrence of widely diffused artifact types. Periods I and II, estimated at 10,000-8000 B.C. and 8000-6000 B.C., are known only from scattered finds of hunting camps. The earliest evidence of seed-grinding tools and field-stone house foundations is found in central Argentina and north Chile during Period III, 6000-3000 B.C. While nomadic hunters continued to occupy the southern part of the continent until historic times, agriculture was well established in Peru during Period IV (3000-1200 B.C.). Period V, from 1200 B.C. until the extinction of the stone-using Indians of Patagonia and Tierra del Fuego in the 20th century, saw the introduction of ceramics to Peru and the southward spread of agriculture, pottery-making, and related activities to Chile and Argentina.