Near Pence in Iron County, Wisconsin — The American Midwest (Great Lakes)
Penokee Iron Range Trail - Plummer Mine Geologic Layer Cake
Iron County Heritage Area
Photographed By Paul Fehrenbach, July 21, 2011
1. Penokee Iron Range Trail - Plummer Mine Geologic Layer Cake Marker
Inscription.
Penokee Iron Range Trail - Plummer Mine Geologic Layer Cake. Iron County Heritage Area. Between 1 to 1 1/2 million years ago sediments of slate and cherty iron carbonates were laid down on top of the granite and greenstone bedrock covering this area. Molten lava flowed over the land, seeping into the great cracks on the surface creating “dikes.” Then the land was submerged under a great glacial sea and more layers, of sandstone and conglomerate rock, were deposited on top.
A catastrophe tilted this geologic layer cake, standing the rock layers almost on end, at a 65 degree angle to the northwest. At this steep pitch, the layers slipped apart. Rain water seeped between the cracks. Over eons the layers of iron carbonate rock oxidized creating a band of low phosphorus hematite, a highly prized form of iron ore used in making steel.
You are standing above the “footwall” – the geologic intersection of a dike and the southern most edge of the iron formation. Along this edge the greatest concentration of iron ore was found. This underground wealth, created eons ago, spurred the development of the Penokee Iron Range.
Between 1 to 1 1/2 million years ago sediments of slate and cherty iron carbonates were laid down on top of the granite and greenstone bedrock covering this area. Molten lava flowed over the land, seeping into the great cracks on the surface creating “dikes.” Then the land was submerged under a great glacial sea and more layers, of sandstone and conglomerate rock, were deposited on top.
A catastrophe tilted this geologic layer cake, standing the rock layers almost on end, at a 65 degree angle to the northwest. At this steep pitch, the layers slipped apart. Rain water seeped between the cracks. Over eons the layers of iron carbonate rock oxidized creating a band of low phosphorus hematite, a highly prized form of iron ore used in making steel.
You are standing above the “footwall” – the geologic intersection of a dike and the southern most edge of the iron formation. Along this edge the greatest concentration of iron ore was found. This underground wealth, created eons ago, spurred the development of the Penokee Iron Range.
Location. 46° 24.458′ N, 90° 17.581′ W. Marker is near Pence, Wisconsin, in
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Iron County. Marker can be reached from Plummer Road, ¼ mile south of Wisconsin Highway 77. Marker is located in the Plummer Mine Headframe Interpretive Park. Touch for map. Marker is in this post office area: Montreal WI 54550, United States of America. Touch for directions.
More about this marker. It appears some knucklehead decided to use the marker for shotgun practice.
Additional keywords. Mining
Photographed By Paul Fehrenbach, July 21, 2011
2. Penokee Iron Range Trail - Plummer Mine Geologic Layer Cake Marker
(Inset) Cross Section of a Typical Inclined Shaft Iron Ore Mine
Photographed By Paul Fehrenbach, July 21, 2011
3. Plummer Mine Headframe
Credits. This page was last revised on June 16, 2016. It was originally submitted on August 2, 2011, by Paul Fehrenbach of Germantown, Wisconsin. This page has been viewed 468 times since then and 11 times this year. Photos:1, 2, 3. submitted on August 2, 2011, by Paul Fehrenbach of Germantown, Wisconsin. • Bill Pfingsten was the editor who published this page.
