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U.S. Geological Survey aerial resistivity map of the Decorah, Iowa area, showing the Decorah crater.. A much older meteorite strike created the Decorah crater during the Middle Ordovician Period, 470 million years ago.
Iowa Geographical Map Server; U.S. Geological Survey Iowa Overview; Geological Society of Iowa This page was last edited on 10 July 2024, at 09:16 (UTC). Text is ...
A well-defined band of pahas runs between Mount Vernon and Martelle, Iowa and is crossed by Iowa Highway 1. Most are in Benton, Linn, Johnson and Jones counties. [citation needed] Casey's Paha State Preserve in Hickory Hills County Park, Tama County, Iowa preserves the southeast end of a 2-mile (3.2 km) long paha. [12]
The Decorah crater, also called the Decorah impact structure, is a possible impact crater located on the east side of the city of Decorah in Iowa, United States. It is thought to have been caused by a meteor about 200 metres (660 ft) wide which struck during the Middle Ordovician Period, circa 470 million years ago.
In 1991 and 1992 the U.S. Geological Survey along with others including the Iowa Geological Survey conducted detailed research in part to test the possible connection of the Manson impact structure with the Cretaceous–Paleogene extinction event. The 40 Ar / 39
Map of the Prairie Pothole Region of North America (U.S. Geological Survey, Northern Prairie Wildlife Research Center) Barringer Slough in Iowa, a remnant of the extensive prairie wetlands that once covered the region.
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Samuel Calvin (February 2, 1840 – April 17, 1911) was Iowa's first systematic geologist, helping to make the first bedrock and landform maps of Iowa, as well as leading geological research throughout the state. He was born in Scotland, attended Lenox College (now defunct) in Hopkinton, Iowa, where he later taught.