The Emerson Phase of Lake Agassiz, independently registered in northwestern Minnesota and northwestern Ontario
Two stratigraphically different sites have been analyzed in different ways, but the results may be interpreted as reflecting a common event: the transgressive Emerson Phase of Lake Agassiz. The southern site at Swift, Minnesota exposes a beach ridge underlain by lakeshore deposits and peat that have been 14C-dated from 10 050 to 9350 years BP. At the other site, a small pond 32 km southeast of Sioux Lookout in northwestern Ontario, lithologic, diatom, and pollen analyses and a radiocarbon age of 9740 years reveal the history of the pond and its basin in relation to Lake Agassiz. Despite more than 300 km of separation it seems probable that the two sites were influenced by the same transgression of Lake Agassiz. The effect and duration differ, however, perhaps because of isostatic adjustments within the Lake Agassiz basin.