Digital hydrogeologic surface of the Midway Confining Unit in Alabama, Arkansas, Illinois,
Kentucky, Missouri, Mississippi. The hydrogeologic unit dataset contains 414 rows and
394 columns representing 1-mile grid spacing. In general, limitations of data interpolation
included areas of sparse geophysical log control points, log datums not clearly defined
for some logs, unknown exact extent of each hydrogeologic unit in subcrop, interpolation
limitations, and values averaged over 1-mile grid spacing.