As previously noted, some of the Paleo-Indian families, upon the retreat of the last glacier, settled in Illinois as they did in the neighboring states, adapted themselves to the changed surroundings, and in so doing developed the Archaic culture or way of life. This phase developed through a series of subcultures though not necessarily identical sequences in all the states or even within Illinois. In southern Illinois, Terminal Archaic seems to have persisted until about 2000 B.C. while in the north, it apparently had developed into Initial (early) Woodland a few centuries earlier. The Baumer subculture, probably arising from the Archaic of Tennessee, appears to have been carried by its bearers into southeastern Illinois along the Tennessee and Cumberland rivers. Although widespread in the Mississippi Valley, the Archaic population was thinly scattered. In northern Illinois and in Wisconsin the Black Sand-Red Ochre culture seems to have developed from the native Terminal Archaic (and Old Copper) possibly around 2500 B.C. The Morton (Central Basin) people appear to have had their cultural roots outside the state and to have combined with the native groups (Black Sand-Red Ochre) they found in the northern counties. Average populational distribution was still low with the small settlements perhaps somewhat more numerous though no more populous than during Archaic times. The early Woodland peoples differed from their predecessors mainly in being pottery-makers. In southern Illinois only they practiced storage of acorns and hickory nuts extensively. About 500 B.C. in northern Illinois the Morton people more or less contemporaneously with similarly advanced peoples in Iowa, Wisconsin, Indiana, Michigan and Ohio, passed into the Hopewellian civilization which was erected on the cultivation of maize, beans, squash and tobacco, and the technologies of the earlier Woodland period. In southern Illinois Baumer developed into the Crab Orchard culture whose people traded with the more northern Hopewellians, intermarried with them and finally adopted the Hopewellian way of life about 100 B.C. A century or two later, Hopewellian in the north of Illinois began to deteriorate and eventually broke up into a number of small subcultures, obviously closely related but still distinguishable archaeologically. The same disintegration of Hopewellian took place in southern Illinois a few centuries later, and by 400 or 450 B.C. Hopewellian had disappeared from all Illinois except possibly in Calhoun County in the west, while south of the Ohio River it still continued to spread and flourish in Mississippi and Louisiana for some centuries.