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Ordovician rocks in Illinois are divided into three series, each separated by an unconformity; from oldest to youngest, these are the Canadian, Champlainian, and Cincinnatian series. Ordovician features in Illinois include the now-buried Glasford Structure in Peoria County , a crater caused by a meteorite impact roughly 455 million years ago.
The Illinois Basin is a Paleozoic depositional and structural basin in the United States, centered in and underlying most of the state of Illinois, and extending into southwestern Indiana and western Kentucky. The basin is elongate, extending approximately 400 miles (640 km) northwest-southeast, and 200 miles (320 km) southwest-northeast.
Locations of quakes magnitude 2.5 or greater in the Wabash Valley (upper right) and New Madrid (lower left) Seismic Zones. The Wabash Valley seismic zone (also known as the Wabash Valley fault system or fault zone) is a tectonic region located in the Midwestern United States, centered on the valley of the lower Wabash River, along the state line between southeastern Illinois and southwestern ...
What The USGS Earthquake Map Tells Us. The color-coded map shows a range of earthquake probability across the U.S. Well known high-risk areas, such as California and Alaska, are coded in dark red ...
Subsidence frequently causes major problems in karst terrains, where dissolution of limestone by fluid flow in the subsurface creates voids (i.e., caves).If the roof of a void becomes too weak, it can collapse and the overlying rock and earth will fall into the space, causing subsidence at the surface.
Land subsidence is a global issue and has different causes. Some are natural, like earthquakes , and some are caused by humans. In the United States, land subsidence from over pumping has affected 45 states and accounts for changes in over 17,000 square miles of land which is an area almost 10 times the size of Glacier National Park in Montana ...
In 2015, the USGS unveiled the topoView website, a new way to view their entire digitized collection of over 178,000 maps from 1884 to 2006. The site is an interactive map of the United States that allows users to search or move around the map to find the USGS collection of maps for a specific area.
Tectonic subsidence is the sinking of the Earth's crust on a large scale, relative to crustal-scale features or the geoid. [1] The movement of crustal plates and accommodation spaces produced by faulting [2] brought about subsidence on a large scale in a variety of environments, including passive margins, aulacogens, fore-arc basins, foreland basins, intercontinental basins and pull-apart basins.