America's Volcanic Past
|"Though few people in the United States may actually experience an erupting volcano, the evidence for earlier volcanism is preserved in many rocks of North America. Features seen in volcanic rocks only hours old are also present in ancient volcanic rocks, both at the surface and buried beneath younger deposits." -- Excerpt from: Brantley, 1994|
Volcanic Highlights and Features:
|[NOTE: This list is just a sample of various Wisconsin features or events and is by no means inclusive. All information presented here was gathered from other online websites and each excerpt is attributed back to the original source. Please use those sources in referencing any information on this webpage, and please visit those websites for more information on the Geology of Wisconsin.]|
Although many people know that glaciers
once covered much of the State, few realize that there were
once volcanoes, lofty mountains, and
tropical coral reefs in Wisconsin at various times in the distant past.
Superior Upland Province:1
The Interior Plains:1
The Interior Plains is a vast region that spreads across the stable core (craton) of North America. This area had formed when several small continents collided and welded together well over a billion years ago, during the Precambrian. Precambrian metamorphic and igneous rocks now form the basement of the Interior Plains and make up the stable nucleus of North America. With the exception of the Black Hills of South Dakota, the entire region has low relief, reflecting more than 500 million years of relative tectonic stability.
Made up mostly of resistant quartzite or granite.
1) USGS/NPS Geology of the Parks Website, 2001
2) Wisconsin Geological and Natural History Survey Website, 2002, Bedrock Geology of Wisconsin Map (1981, revised 1995)
America's Volcanic Past - States and Regions]
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