Date of this Version
Contributions to Geology, University of Wyoming, v. 30, no. 2, p. 137-147.6 figs., December 1994
The digital shaded-relief map of the United States and the synthetic-aperture radar map of the Alliance Nebraska 1º x 2º area prepared by the U.S. Geological Survey (USGS) in the former case and for the USGS in the latter show oriented landforms and lineaments in northwest Nebraska. Parallel and subparallel hills and valleys developed on different geologic materials ranging from shales through sandstones to loess and eolian sand appear to be wind erosional features subsequently modified by running water. The long axes of these hills and valleys generally trend between N40"W and N50"W. Similar features also occur across major areas of the Great Plains from Montana southeast at least to Kansas. Most of the lineaments are in two sets, one trending northeast, the other northwest. There are some east-west and north-south trending lineaments in the western part of the quadrangle, some circular features in the northwest, and some chevronlike lineaments in the north-central part. Some lineaments appear to coincide wholly or in part with known faults in western Nebraska or with extensions of faults in east-central Wyoming into northwest Nebraska. All other lineaments are probably reflections of either jointing or, more likely, of faulting. Additional field work will be needed to verify which of these two, if either, is responsible for any particular lineament.