Geology of Minnesota: Mississippi River – Minnesota City, MN
N 44° 09.040 W 091° 48.039
15T E 595913 N 4889306
This historical marker tells about the geology of the land through which the Mississippi River flows.
Waymark Code: WMRKXR
Location: Minnesota, United States
Date Posted: 07/05/2016
Views: 3
This historical marker tells about the geology of the land through which the Mississippi River flows. It is located at Lock & Dam #5 ten miles north of Winona. The text reads:
Geology of Minnesota: Mississippi River
In its traverse of 2400 miles from Lake Itasca to the Gulf of Mexico, the Mississippi River falls 1475 feet, nearly two-thirds of which is within or along the eastern side of Minnesota. For 300 miles from Minneapolis, its course lies between rocky bluffs bounding a valley from one to six miles in width. The gorge has existed throughout the Pleistocene period of geologic time, during which it has severed as a drainage channel for meltwaters from the glaciers of the Great Ice Ages.
The melting of the ice at the end of each glacial epoch produced torrential floods which scoured the valley 200 feet below the present river surface. During the inter-glacial stages, after the ice had melted, the river, greatly reduced in volume and no longer able to transport sand and gravel, filled its valley to the present level.
The history of the Mississippi River during the last million years, while Minnesota and Wisconsin were undergoing repeated glaciation, is characterized by corresponding cycles of erosion and channel filling, the latter being the phase in which it is now engaged.
Erected by the Geological Society of Minnesota in cooperation with the Department of Highways State of Minnesota. 1960
Marker Type:: Roadside
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Visit Instructions:
A photo of the 'Marker' or 'Plaque' is required to identify the location, plus a picture of the 'Historic Site'.
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