CGRG Bibliography of Canadian Geomorphology
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Author : Fisher, T.G.
Date : 2002.
Title : Recent chronological investigations of Lake Agassiz’s southern outlet.
Publication : 45th Conference of the International Association of Great Lake Research, Winnipeg, Manitoba.
Issue :
Page(s) : 126.
Abstract
Two cores from the southern outlet of glacial Lake Agassiz indicate a minimum of two outlet occupations. A rotosonic core through the Browns Valley alluvial fan recovered 33m of sediment and bedrock. Mud interbedded with two gravel units record lake environments subsequent to two episodes of spillway occupation. Two AMS-14C ages on wood of 10,675±60 (AA37029) and 10,870±170 (AA37030) from the lower gravel and mud overlying bedrock indicate a change from spillway to lake at ~10.7 ka, the transition from the Lockhart to Moorhead phase. This data also implies that the southern outlet was cut to the Campbell level at the end of the Lockhart rather than Emerson phase. A 24m sediment and bedrock core from Big Stone Lake was recovered from a lake-ice platform. Above the Cretaceous shale is 3.5m of fossiliferous, fine-pebble gravel that passes upward into sand-mud rhythmites. Wood fragments or seeds within the gravel range from 9894±61 (AA41886) to 9459±71 (AA38302) 14C BP. A Carex and Scirpus seed date of 9394±76 (AA40114) 14C BP in the lowermost sand-mud rhythmites above the gravel indicate that the final abandonment of the southern outlet of Lake Agassiz had occurred by 9400 14C BP.
Bibliography of Canadian Geomorphology