Late Pleistocene History of Northeastern New England and Adjacent Quebec
The Québec North Shore Moraine System: A major feature of Late Wisconsin deglaciation
Published:January 01, 1985
Jean-Marie M. Dubois, Jean-Claude Dionne, 1985. "The Québec North Shore Moraine System: A major feature of Late Wisconsin deglaciation", Late Pleistocene History of Northeastern New England and Adjacent Quebec, Harold W. Boms, Jr., Pierre LaSalle, Woodrow B. Thompson
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The Québec North Shore Moraine System, extending over 800 km between Manicouagan River and Kenamu River (Labrador), is the longest system known in that part of the Canadian Shield. It is lobated and well defined by a series of parallel till ridges, areas of hummocky ice-contact deposits, proglacial deltas and outwash plains. It is located inland from a few kilometers to about 200 km from the North Shore of the Gulf of St. Lawrence. Between the Manicouagan and Romaine Rivers, the front is at a distance of 25 to 40 km from the southern margin of the Shield except in the Sept-Iles area, where it is less than 10 km inland. From the Romaine River, the front curves northeastward to the Mecatina River, 160 km northwest from the coastline. From there, it trends to the north and then to the northwest at which point it is more than 180 km from the St. Lawrence and over 275 km from the Labrador coast. There is evidence of invasion by the Goldthwait Sea only in the Sept-Iles area and in the Manicouagan river valley. Short segments of two other frontal systems occur along the North Shore, one in the Baie-Trinité area emplaced approximately between 10,300 and 10,100 years B.P., the other in the vicinity of Blanc-Sablon, emplaced circa 11,000 years B.P. No frontal moraine has been mapped north of Québec North Shore Moraine System although there are several large areas occupied by dead-ice morainic deposits in central Québec. The age of the Québec North Shore Moraine System is estimated to be between 9,700 and 9,500 years B.P.
It is suggested that the ice retreated much earlier in eastern Quebec and southern Labrador than in central and western Québec. The Moraine was probably deposited during a cooler interval. As there is no evidence of any significant ice readvance, it is possible that the Laurentide ice sheet remained at that position for several decades. The system marks a well-defined position of the front of the Laurentide ice-sheet during the late Wisconsin déglaciation, and provides a basis for extrapolating other theoretical ice-frontal positions.