As time went on, the Archaic way of life slowly changed and finally disappeared, but probably not so suddenly as might at first appear; for many Archaic customs, tools, and weapons continued to be made and used in the “new” culture by the descendants of rugged earlier people or were adopted by newcomers to the region. Other changes were added through new inventions and incoming people from other regions producing a new culture now generally known as Woodland. THE INITIAL WOODLAND CULTURES[9] (2500-500 B.C.) After 5000 B.C. the temperatures continued to rise producing a climatic interval known as the Thermal Maximum when it was warmer and drier than at the present time. After reaching its high point, the temperature gradually declined and probably ended in southern Illinois about 2100 B.C. or later in a climate much like that of today. By projecting the rate of deposit from the eight- to the eleven-foot level of the Modoc Rock Shelter up to the five-foot level where the Archaic remains appear to end, we secure a date for its upper limit of about 2100 B.C. (Deuel 1957, p. 2). The remains between the five- and eight-foot depths are scantier and less varied than in the earlier (lower) layers and may indicate a cultural group in a losing struggle to maintain itself under changing conditions. [Illustration: Fig. 11. Potsherds from the Lake Baikal in southern Siberia resemble those of Initial and Classic Woodland (Hopewellian) in Illinois. The letters with subscripts refer to Siberian pottery. A-E, reduced to ½ actual size; F-H, reduced to ¹/₁₆ actual size. (Siberian pottery from Richthofen in ANTHROPOS, 1932: 128, 129, 130; Illinois pottery from Illinois State Museum collections.)] In northern Illinois, similar climatic conditions were developing. There, possibly as early as 2500 B.C., a new culture, the Initial (early) Woodland, was coming into existence. At any rate, groups living there some time prior to 1000 B.C. made pottery, placed their dead in cemeteries and in low burial mounds in a flexed or “doubled-up” position, occasionally with food, personal ornaments and other funeral offerings. [Illustration: Fig. 12. A flint dagger or hunting knife from “Red Ochre subculture” of Initial Woodland. (B.B.)]