Comparison of computer-based and manual coal resource estimation methods for the Cache coal bed, Recluse Geologic Model Area, Wyoming

Coal resources have been estimated, using both manual and computer methods, for the Cache coal bed in the Recluse Geologic Model Area, which covers the White Tail Butte, Pitch Draw, Recluse, and Homestead Draw SW 7?-minute quadrangles in Campbell County, Wyoming. Approximately 300 coal thickness measurements from drill-hole logs are distributed throughout the area The Cache coal bed and associated strata are in the Paleocene Tongue River Member of the Fort Union Formation. The depth to the Cache coal bed ranges from 269 to 1,257 feet. The coal bed is as much as 31 feet thick but is absent in places. Comparisons between hand-drawn and computer-generated isopach maps show minimal differences. Total coal resources estimated by hand show the bed to contain 2,228 million short tons or about 2.6 percent more than the computer-calculated figure of 2,169 million short tons.