Two sections of sediments from a shallow lake on The Pas moraine gave a14C age of 7 220 ± 110 years, a likely minimum age for the recession of Glacial Lake Agassiz II. Three pollen zones are recognized as follows: Zone 1, from 7 300 to about 6 200 B.P., dominated by NAP(40-75%) with 6-22% spruce, 1-10% juniper and minor proportions of other trees, interpreted as a treeless vegetation, except for scattered spruce, dominated by juniper, grasses, sagebush and herbs. Zone 2, from 6 200 to 3 500 B.P., dominated by pine, with a mixed forest of poplar, pine and spruce. Zone 3, an assemblage occurring from 3 500 B.P. to the present, consisting of spruce, pine and birch, representing the modern mixed boreal forest. These findings agree with archaeological data suggesting a shift from a plains to a woodland culture. © 1975.
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