Digital Data of Structural Contours from Previously Published USGS Mississippi Embayment Studies

This digital dataset is a result from the goal within the U.S. Geological Survey’s (USGS) National Cooperative Geologic Mapping Program to convert surficial data that were previously published in non-digital format to digital, vector-based data suitable for use by the public and in USGS studies. The objective of the data conversion is to reproduce the original published mapping with little to no added interpretation. This digital data release captures subsurface geologic data within the Mississippi Embayment region, using two publications focusing on water resources and general geology to fulfill missing pieces of a larger network of data. These two legacy publications, ‘Maps of upper Mississippi embayment Paleozoic and Precambrian rocks’ by Richard L. Dart, 1995 and ‘General Geology of the Mississippi Embayment’ By E. M. Cushing, E. H. Boswell, And R. L. Hosman, 1964- were chosen due the focus on structural and isopach data within their publications. There were six selected map figures with structural data digitized, two from Dart, 1995 and four from Cushing, 1964. This does not include any additional input data or speculative interpretations, strictly published structural contour features. While there were six identified maps, there are only five sets of vector data, this is due to combining both sets of Paleozoic features into one feature class- one can differentiate the two based on the listed source attribute. This geologic data set includes structure contour data for the top of the Eocene Sparta Sand, the base of Eocene Cane River Formation and stratigraphic equivalents, the top of Cretaceous rocks, the top of Paleozoic rocks, and the top of Precambrian basement rock. The Sparta Sand is identified as the middle part of the Eocene and is a formation within the Claiborne Group, the Cane River Formation underlies the Sparta Sand and includes all rock from the top of the Carrizo Sand to the base of the Sparta Sand. The Mississippi embayment is an extensive sediment-filled geologic structure underlying parts of eight states in the southcentral U.S. that provides large quantities of groundwater from numerous aquifers to residential and industrious areas. Due to the large size of the Mississippi Embayment and its cross-cutting political boundaries, the names given to the many geologic units may vary from region to region. It is common to call a unit by the name given by the local area, for example; west Tennessee terms the Memphis aquifer the Sparta Sand and Corrizo Sand aquifers, additionally the Sparta Sand is referred to as the Cane River in Arkansas and Louisiana and is the equivalent to the Mount Selma Formation of Texas and the Tallahatta Formation in Mississippi and Alabama.