Twenty thousand years ago, as the world's climate begins slowly to warm after the last major glaciation, and Asian peoples crossor continue to crossthe Bering Strait between Siberia and Alaska, these new Americans spread out through the two large continents. Reaching temperate environments, they begin to diversify. While continuing to hunt game for food, they also gather edible plants and shellfish. Shelter is found in caves or rocky outcroppings, or built in tentlike structures of wood and animal skin. Weapons and tools are fashioned from wood, stone, and bone. Cordage, netting, and basketry develop and fiber-tempered pottery is eventually fired. The practice of placing significant burials beneath earth-and-stone mounds is initiated.
ca. 8000 B.C. American Archaic cultures are those that occur between Paleoindian hunter groups and the peoples who have realized some combination of pottery making, burial mound construction, and garden technology. The combination varies from area to area.
ca. 5000 B.C. Indian Knoll and other shell-mound sites along the Green River, in Kentucky, begin to be occupied.
ca. 4000 B.C. Small conical burial mounds are the earliest earthworks along the Mississippi.
ca. 3500 B.C. People of the Old Copper culture around the Great Lakes use native copper for tools.
ca. 3000 B.C. Lovelock Cave, an open rock shelter in western Nevada, is inhabited, and remains in use until historic times. Large quantities of perishable materials such as bird decoys, baskets, basketry items, featherwork, and skin blankets have been discovered there.
ca. 2500 B.C. Pottery is made in the lower Savannah River valley of Georgia and South Carolina.