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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.
Lake Decatur is a 2,800-acre (11 km 2) reservoir located in the city of Decatur, Illinois, USA, east of downtown. The city and lake both share the name of U.S. Navy Commodore Stephen Decatur. The lake is 613 feet (187 m) above sea level and has a watershed of 925 square miles (2,400 km 2) or 592,000 acres (240,000 ha) reaching into parts of ...
Instead of being located in the relatively flat, rolling terrain characteristic of most of Illinois, the lake is located in an unglaciated zone of deep sandstone valleys and steep slopes. Devils Kitchen Lake is located in one of these valleys, and it is one of the deepest lakes in Illinois. Sections of the lake are as deep as 90 feet (27 m). [1]
Paleogeographic reconstruction showing the Illinois Basin area during the Middle Devonian period. [9] Almost all Silurian rocks in Illinois are deep-water limestone and dolomite deposits; reef habitats were common, and fossils of reef organisms are locally highly abundant, including corals, brachiopods, crinoids, stromatoporoids, and bryozoans. [6]
The Illinois side includes Henry County, Mercer County, and Rock Island County. [4] In extreme northwestern Illinois the Driftless Zone, a region of unglaciated and therefore higher and more rugged topography, occupies a small part of the state. Charles Mound, located in this region, is the state's highest elevation above sea level.
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 m (660 ft) or the point of transition from continental shelves to continental slopes. [ 1 ] [ 2 ] Conditions within the deep sea are a combination of low temperatures, darkness, and high pressure . [ 3 ]
A seafloor map captured by NASA. Bathymetry (/ b ə ˈ θ ɪ m ə t r i /; from Ancient Greek βαθύς (bathús) 'deep' and μέτρον (métron) 'measure') [1] [2] is the study of underwater depth of ocean floors (seabed topography), lake floors, or river floors.
Major fractures zones of the Atlantic can be seen on this ocean depth map Active Atlantic Ocean fracture zones are perpendicular to the mid-ocean ridges (black lines) in orange shaded region In the Atlantic Ocean most fracture zones originate from the Mid-Atlantic Ridge , which runs from north to south, and are therefore west to east oriented ...