Nebraska Academy of Sciences


Date of this Version



Published in Transactions of the Nebraska Academy of Sciences, Volume 1 (1972).


Copyright 1972 by the author(s).


It has been postulated that some cultural movements or conditions may be correlated with climatic episodes. One area where such correlations can be attempted lies in the Dakotas along the Missouri River mainstem where there is an apparent correspondence between dates of certain widespread climatic events and sequential episodes of native cultural history. During the period ranging from A.D. 700-1200 and from A.D. 1300 on into the nineteenth century significant changes of a climatic nature may have affected Indian societies.

The correlation of some climatic episodes or conditions with cultural movements is being attempted in an area of the Dakotas along the Missouri River mainstream.

The close correspondence between the dates of certain widespread climatic events defined by Reid A. Bryson and a sequence of episodes in the history of the native cultures of the Missouri Valley in the Dakotas (Fig. 1) suggest a close correlation between climatic and cultural changes (Lehmer, 1969).

The correspondence between a sequence of native cultures in the Missouri Valley and certain climatic episodes may have begun as early as A.D. 900 with the climatic episode known as the Neo-Atlantic. This period is characterized as one of warm moist conditions due to influxes of moist tropical air. It was a period which produced favorable conditions for maize horticulture and correlates with the first appearance of horticultural villages in South Dakota (Caldwell, 1968, p. 108-109; Lehmer, 1968, p. 12). Griffin (1967) mentions that agricultural societies in the Missouri and Upper Mississippi Valleys and in the Great Lakes northeastern United States had their primary growth and development during the A.D. 700-1200 period. During this time open water appeared in the Canadian Arctic, summer rains extended further into the southwest, the raising of maize would have been possible in the plains area (Bryson and Julian, 1963). Approximately A.D. 1200 the increasing flow of the westerlies (Bryson and Baerreis, 1968, p. 29) terminated the Neo-Atlantic and initiated the period designated the Pacific I. From A.D. 1200 to about A.D. 1450 the westerlies continued to increase; temperatures were lowered; and there was a decrease in precipitation. Between A.D. 1300 and continuing up into the 1800's, there were significant climatic changes which influenced Indian societies (Griffin, 1967, p. 171). The Pacific I (Baerreis and Bryson, 1965) correlates with the noticeable reduction of the extent of area occupied by the Missouri Valley cultures.