Minnesota
River Valley
Geologic Markers
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Enrich your Minnesota River Valley Collection experience with a tour of the area that includes these three Geologic Markers.
(The red dots.)
Order Form
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Today’s Minnesota River is termed by geologists an underfit river, a small stream flowing in the great valley cut by the Glacial River Warren. Initially, the French called the Minnesota the Rivére St. Pierre. But after Jonathan Carver viewed the bountiful harvest from the adjoining forests and fields, the river was anglicized to St. Peter’s.
The specimens in this collection represent the most outstanding geologic features from the Minnesota River Valley, and may be placed in one or more of the following categories: 1) Precambrian rocks, 2) early Paleozoic sedimentary rocks, 3) Cretaceous clays, 4) glacial land forms, and 5) fossils.
Nice Old Rocks
Some of the oldest rocks in the world, formed more than 3 ½ billion years ago, can be found along the Upper Minnesota River where bedrock has been exposed by erosion. Recent road building that involved a touch of explosives gives a fresh-fracture face to the specimen of Morton Gneiss in this collection.
A roadcut through Morton gneiss
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Primitive Life Fossils In The Valley
Three members of the Ordovician-aged Prairie du Chien Formation are quarried in the Minnesota River Valley in the Metro area. They include the Shakopee Formation; made up of the Willow River and New Richmond Members, and the Oneota Dolomite Member. Preserved in the upper portion of the Oneota Dolomite is an abundance of fossil stromatolites. A specimen is included in The Minnesota Valley River Valley Collection as well in the Minnesota & More Fossil Collection. Individual specimens are available on the Minnesota Rock, Fossil & Mineral Specimens 1 & 2 pages.
A typical hardrock quarry in the Minnesota River Valley.
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Minneopa State Park
Established in 1905, this is Minnesota's third oldest state park. Visit twin waterfalls plunging 35 feet into the valley below. Hike on a glacial terrace overlooking the Minnesota River. Here is a link to Minneopa State Park Explore Minnesota
The entire park lies within the banks of the Glacial River Warren, which drained Glacial Lake Agassiz at the end of the last period of glaciation, some 15,000 years ago. These banks are easily viewed if a visitor looks north and south from the vantage point of Seppmann Mill. Also visible are the many large boulders scattered upon the prairie grassland, which lies in the bed of that ancient river. These boulders, known as "glacial erratics," are made of parent material entirely different than that commonly found in this area. They were transported from a region far to the north and were deposited here by the melting ice of the retreating glacier. The word Minneopa is derived from the Dakota language and is interpreted to mean "water falling twice." As the retreating glacier melted and drainage patterns emerged, the valley of Minneopa Creek was formed. "Downcutting" occurred until a more resistant layer of rock was encountered and this layer forms the ledge from which the twin waterfall drops.
Here is one more link: MN DNR State Parks.
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The Minnesota River Valley Collection is useful to non-professionals who simply wish to learn more about the geologic history of Minnesota. It is not intended to be a one-stop, comprehensive collection. It is useful to anyone with an interest in earth science or the geology of Minnesota.
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C'mon in and shop for rocks.
Click on the link below.
My Rock Shop Order Form
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If your are so inclined, explore the Minnesota River Watershed Alliance bulletin board and register to receive regular updates on what’s happening in the Minnesota River Watershed.
Here is one final link to another fine organization whose main concern is the Minnesota River Valley: CURE (Clean Up the River Environment).
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If you experience problems with this page, please contact me at the following address:bjgoetteman@att.net
Copyright © 2000-2008 Bruce Goetteman. All Rights Reserved. To obtain copies of images, select the Field Guide Album on the Order Form.
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