Date of this Version
Geologic Map GMC-34
School of Natural Resources, Conservation and Survey Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln. http://nebraskamaps.unl.edu
This map is necessarily generalized. It is based primarily on data from 7.5’ surficial geologic quadrangle maps of the map area prepared by the authors principally from 1991 to 2000, from Voorhies (unpub. data, 1974), as well as data from test-hole drilling done across the quadrangle by the Conservation and Survey Division, University of Nebraska, and its cooperators over many years since the 1930s. For more detailed information, consult the geologic data files of the Conservation and Survey Division, School of Natural Resources, University of Nebraska-Lincoln. The quadrangle is mostly covered by vegetation and Holocene sediments. Limited good exposures of older sediments and bedrock occur usually in road cuts, in quarry and pit excavations, on valley sides, on stream and river cut banks, and in isolated erosional remnants on uplands. Users of this map should remember that the scale of the map is small and allows only a general picture of the geology of the quadrangle to be depicted. Users should check with the authors regarding specific sites and, if necessary, do field checks of these sites. As new data become available the authors intend to update the data sets used in preparation of this quadrangle text and maps and to issue refined versions, if necessary. The earliest geologic map that included part of the study area was published by Charles Lyell in 1845 (Diffendal, 1993). Other geologic maps at different scales that include all or parts of the map area are by Darton (1899, 1905), Condra (1908), Schulte (1952), Mendenhall (1953), Lampshire (1956), Burchett (1986), Weeks and Gutentag, (1981), Weeks and others (1988), Swinehart and others (1994), and Diffendal and Voorhies (1994). Geologic maps of adjacent areas in Nebraska and South Dakota include Burchett and others (1975), Burchett and others (1988), Diffendal (1991), and Souders (2000) for Nebraska and Stevenson and Carlson (1950, 1951), Baker and others (1952), Collins and French (1958), Schoon and Sevon (1958), Stevenson and others (1958), and Stevenson and others (1959) for parts of South Dakota. Detailed groundwater investigations and associated stratigraphic test drilling (of parts or all of the map area) were done by Darton (1905), Condra (1908), Reed (1944), Keech and Schreurs (1953, 1954), Cronin and Newport (1956), Reed (1957), Smith (1958), Newport (1959), Souders and Shaffer (1969), Souders (1976), Gutentag and Weeks (1980), Luckey and others (1981), Lawton and Hiergesell (1988), Weeks and others (1988), Pierce (1989), Rahn and David (1989), Burchett and Smith (1992), and Lackey and others (1995, 1998a, 1998b, 2000).