Geology of the Hastings County Region
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GT.US
N 44° 44.150 W 092° 51.478
15T E 511245 N 4953614
This marker was found in a small park near the junction of US-61 and US-55 in Hastings.
Waymark Code: WM7P5Q
Location: Minnesota, United States
Date Posted: 11/16/2009
Views: 16
"Hasting lies just south and East of the last glaciation. About 20,000 years ago, a lobe of ice, called the Superior lobe, advanced from the Lake Superior basin and crossed the ancient bedrock valley of the Mississippi river between St. Paul and Hastings. There it filled the valley with ice and sediment (silt, sand, gravel and boulders). Glacial ice trapped in the valley was then covered by more sediment as the ice lobe slowly receded. The melting lobe then deposited a large amount of sediment along its edge creating a swath of hills of which a portion curves around the twin cities on the south and west. This deposit of glacial sediment is called the St. Croix moraine. Melt water streams flowed out from the Superior lobe, breached the moraine, and built a large outwash plane of sand and gravel. This outwash deposit buried the Mississippi River Valley south of the moraine as far as Hastings.
About 16000 years ago, another lobe of ice, the Des Moines lobe, advanced from the northwest, through central Minnesota, and eventually extended as far south as Des Moines Iowa. Locally, melt water from its eastern margin drained eastward and carved a river valley to the Mississippi river at the present site of Hastings. The modern Vermillion River is but a shrunken remnant of that stream.
Ice block buried within the ST. Charles moraine and filling the ancient bedrock valley of the Mississippi River were insulated by sediment and melted very slowly. Eventually, their melting collapsed the moraine and reestablished the Mississippi River valley for drainage. As the glacial lobes continued to recede, large volumes of melt water flowed through the Mississippi again, forming numerous terraces and exposing the bedrock valley. When the influx of glacial melt water ended, the volume of water in the Mississippi decreased greatly to what we see today.
Erected by the geological society of Minnesota in partnership with the Minnesota department of transportation and the Minnesota Geological Survey 1998."
This marker is also referenced in Minnesota history along the highways: a guide to historic markers and sites By Sarah P. Rubinstein
Marker Type:: City
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