To characterize the proposed Rocky Mountain 1 underground coal gasification test site near Hanna, Wyoming, 30 drill and/or core holes were completed and downhole geophysically logged during the summer of 1986. Core testing was conducted to identify coal quality and predict behavior during gasification. Data were then interpreted to provide information on process parameters and restoration to be used by process and environmental engineers. The coal seam at the Rocky Mountain 1 site dips to the northeast at 7/sup 0/ and shows only minor folding of strata. A fault with 30 feet of stratigraphic displacement is located approximately 300 feet northeast of the northern boundary of the proposed burn area. From core and outcrop observations, tectonic fracturing is predicted to be minor, although local areas of fracturing may exist. Overburden stratigraphy consists of interbedded sandstone, siltstone, and shale with minor coal. The Hanna No. 1 coal (target of the experiments) is approximately 30 feet thick. It contains an upper bench approximately 3 to 4 feet thick of lower quality (higher ash, lower Btu), a central bench about 20 feet thick of higher quality (lower ash, higher Btu), and a lower bench approximately 3 to 4 feet thick also of lower quality. The benches are separated by shaley zones approximately 1 to 2 feet thick, which are correlative across the site. Another shaley zone exists near the base of the central bench. The coal varies vertically and somewhat laterally across the site but averages at a high volatile C bituminous rank. Average-as-received proximate analysis values for the coal are 8.8 wt % moisture, 27.3 wt % ash, 32.0 wt % volatile matter, 31.9 wt % fixed carbon, and approximately 8600 Btu/lb heating value. Average-as-received sulfur content is 0.7 wt %. Site characteristics are very amenable to underground coal gasification, and no hindrances to the test due to geologic conditions are expected. 9 refs., 21 figs., 6 tabs.