This chapter is a re-release of U.S. Geological Survey Bulletin 1839-K, of the same title, by Ryder and others (1992; online version 2.0 revised and digitized by Robert D. Crangle, Jr., 2003). It consists of one file of the report text as it appeared in USGS Bulletin 1839-K and a second file containing the cross section, figures 1 and 2, and tables 1 and 2 on one oversized sheet; the second file was digitized in 2003 as version 2.0 and also includes the gamma-ray well log traces.