Gordon Cameron

M. Sc. Thesis

Seismostratigraphy of Late Quaternary Sediments and Lake Level History, Eastern Lake Erie

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Seismo- and lithostratigraphic analysis of unconsolidated sediments in the Long Point area of eastern Lake Erie reveals two stratigraphic sequences.

The lower sequence forms a wedge of material, thickest in the centre of the basin (ca 50 m), which thins shoreward where it commonly pinches out against an overlying regional unconformity. This lower sequence comprises glacial drift and stratified proglacial and postglacial sediments. The upper sequence forms a continuous wedge-like cover, up to 40 m thick in the centre of the basin, which thins shoreward. The upper sequence (Holocene in age) consists of laminated or massive muds, muddy sandy lag and contains, in places, relict brown and gray beach sand at ca 20 to 30 meters below datum (m.b.d.).

Port Huron Ice reached Long Point Bay between 12.5 and 13 ka depositing glacial drift on the basin flanks and bedrock highs while delivering fine-grained sediments to deeper portions of the basin. Ice retreat about 12.5 ka lowered lake levels and allowed drainage over the Niagara escarpment. Lake levels were probably maintained above present lake level by high volume flow over moraine crests on the escarpment until 10.5 ka when Upper Great Lakes waters were diverted away from the Erie basin. Lake levels rose (from a low of 30 m.b.d.) throughout much of the Holocene Epoch. The Nipissing flood (ca 5 ka) renewed Upper Great Lakes flow and temporarily raised lake levels ca 5 meters above datum (m.a.d.). Water levels continued on an upward trend after falling ca 10 m.b.d. (ca 3.9 ka).

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Pages: 173
Supervisor: David Scott