This map shows the structural configuration of the top of the Travis Peak or Hosston Formations in feet below sea level. The map was produced by calculating the difference between a datum at the land surface (either the Kelly bushing elevation or the ground surface elevation) and the reported depth of the Travis Peak or Hosston. This resulted in 18,941 wells for which locations were available. After deleting the wells with obvious data problems, a total of 18,933 wells were used for the map. The data are provided as both lines and polygons, and the proprietary wells that penetrate the top of the Travis Peak or Hosston Formations are graphically displayed as quarter-mile cells. The well information was initially retrieved from the IHS Energy Group, PI/Dwights PLUS Well Data on CD-ROM, which is a proprietary, commercial database containing information for most oil and gas wells in the U.S. Cells were developed as a graphic solution to overcome the problem of displaying proprietary PI/Dwights PLUS Well Data. No proprietary data are displayed or included in the cell maps. The data from PI/Dwights PLUS Well Data are current as of April 2001.