Geological History
The Traverse Gap was cut at the end of the last ice age. The Laurentide Ice Sheet decayed and receded as the Wisconsonian glaciation drew to a close, and Glacial Lake Agassiz formed from its meltwaters. Outlets to the north were blocked by the glacier, and the outlet to the south was dammed by the Big Stone Moraine which had been left by the retreat of the ice sheet. Lake Agassiz filled until it overtopped the moraine about 11,700 years ago. The resulting enormous outflow of the lake carved a natural spillway through the moraine, through which cascaded Glacial River Warren. This great river not only created the gap, it also cut the valleys of the present-day Minnesota and Upper Mississippi Rivers. River Warren drained Agassiz in two or more intervals over the next 2300 years, separated by times when the ice sheet receded sufficiently to uncover other outlets for Lake Agassiz. About 9400 years ago, Agassiz found a permanent outlet to the north. With its former source now draining elsewhere, River Warren ceased to flow, and the spillway gorge became the Traverse Gap.
Read more about this topic: Traverse Gap
Famous quotes containing the words geological and/or history:
“The crystal sphere of thought is as concentrical as the geological structure of the globe. As our soils and rocks lie in strata, concentric strata, so do all men’s thinkings run laterally, never vertically.”
—Ralph Waldo Emerson (1803–1882)
“A man will not need to study history to find out what is best for his own culture.”
—Henry David Thoreau (1817–1862)