CGRG Bibliography of Canadian Geomorphology
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Author : Driver, J.C.; Hills, L.V.; and Reeves, B.O.K.
Date : 1985
Title : Postglacial pollen and paleoclimate in southwestern Alberta and southeastern British Columbia. part 3: Holocene palynology of Crowsnest Lake, Alberta with comments on Holocene paleoenvironments of the southern Alberta Rockies and surrounding areas
Publication : Climatic Change in Canada 5, Critical Periods in the Quaternary Climatic History of Northern North America. Edited by: C.R. Harington. National Museums of Canada, National Museum of Natural Sciences, Syllogeus Series
Issue : 55:
Page(s) : 370-396
Abstract
In the preceding sections we show that the sequence of environmental events postulated for Crowsnest Pass can be equated with similar developments in other areas of Alberta and northwest North America. A generalized postglacial climate consists of an early warming trend, culminating in the Altithermal, with warmer temperatures and lower rainfall than today. Following this, two cold periods are readily documented, but the situation after 2000yr B.P. is less certain. Major changes affecting the prehistoric inhabitants of the Crowsnest Pass were probably few. After 10,500 yr B.P., grasslands were almost certainly established in Crowsnest Pass,and must have provided good grazing for ungulates. Forest zones gained elevation, perhaps reaching modern limits at about 9000 yr B.P. A brief decline in elevation may have occurred from 8500 to 8000 yr B.P., but the extent of the grasslands cannot have been seriously affected. Expansion of the grassland zone started shortly after this, and by 7500 or 7000 yr B.P., the area had increased considerably. Then, subalpine forest moved up the valley sides,and increased herds occupied the grasslands and montane forest. Between 6000 and 5000 yr B.P., a change took place. Temperatures dropped, precipitation increased, and less productive subalpine forest expanded into the valley grasslands, reducing montane forest to a thin strip. At that time, vegetation zones may still have been somewhat higher in elevation than today. Following a second grassland expansion, cool, wet conditions reappeared, possibly reducing grasslands to an area approximately the same as today. with minor fluctuations in climate, this situation continued until today. We emphasize that changes in the Crowsnest Pass have been largely quantitative. Undoubtedly the main factor in assessing the effects of environment on prehistoric man is the extent of the grasslands, because these provided habitat for the ungulates which were the subsistence base. Grasslands have not disappeared from the Crowsnest Pass at any time in the Holocene. Thus, there has always been a potential for a population of ungulates in the area - a potential probably unrivalled by any other valley in Alberta within the mountain front.
Bibliography of Canadian Geomorphology