Soils and Geology of Wisconsin Field Trip, May 2007
Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay
May 17, 2007

Irvine Park, Chippewa Falls
Amnicon Falls State Park
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Amnicon Falls is created by the Douglas Fault juxtaposing Keeweenawan volcanic rocks and sedimentary rocks. |
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The fault is in the gully. There are at least five fault strands where slivers of conglomerate alternate with sandstone and siltstone. The floor of the gully is a band of conglomerate. It is in fault contact on the right with volcanic rocks. On the left it is in fault contact with horizontally bedded sandstone. |
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Professor Luczaj points to a fault sliver of conglomerate, which is in fault contact with horizontally bedded sandstone. |
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View of one of the fault strands. |
Big Manitou Falls, Pattison State Park
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The Douglas Fault forms a prominent scarp because it juxtaposes hard volcanic rocks with soft sedimentary rocks. Since the scarp is erosional, not due to actual displacement, it is not a fault scarp. Such a scarp is sometimes called a fault-line scarp. |
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Approaching the Douglas Fault. |
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Big Manitou Falls, 50 meters high, is the highest waterfall in Wisconsin. |
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Looking into the gorge of Big Manitou Falls. |
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Downstream from the falls are pink Keeweenawan sandstone. The water was too high (not dangerous, just inconvenient) to allow us to get close to the contact (which is concealed anyway but with good enough exposures to interpret relationships.) |
May 18, 2007

Mesabi Range, Eveleth, Minnesota
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Middle Proterozoic iron formation on a highway cut on the outskirts of Eveleth. |
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In an active mine. The iron ore here has been excavated away. The smooth slope is the top of the next formation down, and the bank above it is waste rock used to backfill the pit. |
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Tire, $100,000. Chain to protect it from wear, $40,000. Group photo, priceless. |
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An overlook near Virginia offers views into a chain of abandoned pits. |
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My truck can eat your truck. |
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Lunch at the overlook. |
Soudan Iron Mine, Minnesota
Archean Graywacke Near Tower
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Near Tower are beautiful cleaned outcrops of Archean graywacke with some of the best graded bedding anywhere. Here we have some excellent load casts. But they're pointing in opposite directions! |
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And here's why: isoclinal folding. |
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Not far away at this dam are more Archean graywackes. These are not folded at all (suggesting that the folding only a few kilometers away is highly localized, possibly soft-sediment) but show wonderful examples of the evolution of brittle shear zones. |
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It's a ways yet to our camping stop at Tettegouche State Park on the lake, so we get pizza to go for supper in Ely. |
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It looks short on the map but it's a windy, hilly road. |
May 19, 2007

Tettegouche to Beaver Bay
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Rhyolite just off Highway 61. |
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Rhyolite cliffs on the lakeshore at Palisade Head. Shovel Point is in the distance. |
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Obvious fault a few kilometers south of Tettegouche State Park. |
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At Beaver Bay there are huge anorthosite inclusions in the gabbro. |
Gooseberry Falls State Park, Minnesota
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A wonderful waterfall right off Highway 61. |
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The several shelves that define the falls are formed by flow tops. Pahoehoe texture is visible here. |
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There are numerous small potholes in the basalt. |
Sedimentary Interbeds, Duluth, Minnesota
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Leif Erikson Park in Duluth has a nice small outcrop of Keeweenawan sedimentary interbeds within the volcanic rocks. |
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For those of you who didn't know Leif Erikson got as far as Duluth. |
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A bridge over the tracks leads to the beach. |
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The sedimentary outcrop is small but has excellent cross bedding. |
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May in Duluth. |
Interstate Park, Minnesota
Cambrian-Proterozoic Unconformity
May 20, 2007

Interstate Park, Wisconsin
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The Wisconsin side is less visited than the Minnesota side but still has lots of interesting geology. Here are the Dells from the Wisconsin side. |
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The most spectacular pothole on the Wisconsin side is this one. How you get a pothole on a knob like this is a mystery. |
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"His high exaltedness, the Great Jabba the Hutt, has decreed that you are to be terminated immediately. You will therefore be taken to the Dune Sea, and cast into the pit of Carkoon, the nesting place of the all-powerful Sarlaac. In his belly you will find a new definition of pain and suffering as you are slowly digested over a thousand years." |
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Water collects at the Cambrian-Keeweenawan unconformity and seeps out to create a small wetland floored by histosols, as Dr. Fermanich explains. |
Willow River State Park, Wisconsin
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Created 08 September 2006, Last Update 15 January 2020