Description: Several authors indicated that the sands within the St. Peter Sandstone are continuous, especially in the middle portions of the unit (Kreutzfeld, 1982; Barnes and others, 1992). The St. Peter Sandstone is partially offset by a number of faults, and these faults can significantly affect sand-body continuity. Therefore, we chose to use the map of Collinson and others (1988), which shows the locations of major faults that offset the St. Peter Sandstone to characterize sand-body continuity, because faulting rather than lithology is the principal factor influencing sand-body continuity of the St. Peter in the central Illinois Basin.
Service Item Id: f64fb0bf2e0149dcab422ce830b63937
Copyright Text: Collinson, C., Sargent, M. L., and Jennings, J. R., 1988, Chapter 14: Illinois Basin region, in Sloss, L. L., ed., The Geology of North America, v. D-2, Sedimentary Cover—North American Craton: U.S.: Decade of North American Geology: Geological Society of America, p. 383–426.
Description: This line shapefile represents the major fault lines in the United States. A fault is a fracture or fracture zone in the Earth's crust along which rocks on one side have moved significantly with respect to those on the other side. This layer is part of the Geologic Map of the United States, originally published at a scale of 1:2,500,000 (King and Beikman, 1974b). It excludes Alaska and Hawaii. These data depict the geology of the bedrock that lies at or near the land surface, but not the distribution of surficial materials such as soils, alluvium, and glacial deposits. This is a revised version of the April 2004 data set. This map complements the Generalized Geologic Map of Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands by Reed and Bush. This layer is part of the 1997-2014 edition National Atlas of the United States.
Service Item Id: f64fb0bf2e0149dcab422ce830b63937
Copyright Text: National Atlas of the United States. (2005). Fault Lines: Geology of the Conterminous United States, 2005. National Atlas of the United States. Available at: http://purl.stanford.edu/tt369vk9000.
Copyright Text: Hoholick, D. J., 1980, Porosity, grain fabric, water chemistry, cement, and depth of the St. Peter Sandstone in the Illinois Basin: University of Cincinnati, Master's thesis, 72 p.
Description: We chose to use the map of Collinson and others (1988) because it shows thickness at 50 (rather than 100) ft intervals. Kreutzfeld (1982) pointed out that the thickness of the St. Peter Sandstone is much more variable than the formation-thickness map indicates. The variation in thickness is due to postdepositional erosion and its highly irregular lower boundary. The base of the St. Peter Sandstone is a major regional unconformity (Collinson and others, 1988; Young, 1992b).
Service Item Id: f64fb0bf2e0149dcab422ce830b63937
Copyright Text: Collinson, C., Sargent, M. L., and Jennings, J. R., 1988, Chapter 14: Illinois Basin region, in Sloss, L. L., ed., The Geology of North America, v. D-2, Sedimentary Cover—North American Craton: U.S.: Decade of North American Geology: Geological Society of America, p. 383–426.