During continental glaciation, the tremendous weight of the glacier depressed the area of the St . Lawrence so much that a lower point of drainage was established eastward through the present river system.
12.
The relative warmth of the Pacific Ocean due to the shutting down of the Oyashio Current and the presence of large'east-west'mountain ranges were secondary factors preventing continental glaciation in Asia.
13.
Stratigraphic and geomorphic relationships indicate that this impact structure formed sometime after Middle Ordovician, about 470 million years ago, and before the first continental glaciations of North America at the beginning of the Quaternary, about 2.6 million years ago.
14.
He graduated from special school No . 49 in Moscow in 1970, the Faculty of Geography of Moscow State University in 1975, and received Ph . D . from the Institute of Geography of the Soviet Academy of Sciences in 1979, ( the thesis is devoted to the ancient continental glaciations ).
