Friday, April 11, 2008
What primary geological processes or events shaped the land here? Q24 of The Big Here Quiz
In the beginning (about 2 billion years ago) "two tectonic plates fused and created the Midcontinent Rift, forming a valley that was the basis of Lake Superior. When a second fault line, the Saint Lawrence rift, formed approximately 570 million years ago, the basis for Lakes Ontario and Erie was created, along with what would become the St. Lawrence River." Molten magma caused "the highlands to sink and form a mammoth rock basin that would one day hold Lake Superior." Then the geological process of glaciation defined the area which we now know as the (Laurentian) Great Lakes.