Two field tests were conducted in the G seam of the Fort Union Formation on the North Knobs track near the eastern rim of the Continental Divide Basin near Rawlins, Wyoming. The test site was selected in 1978. An environmental assessment and a general test plan were prepared. The first US test of underground coal gasification for steeply dipping beds (UCG/SDB) was conducted from October to December 1979. Test 1 was considered to be successful, as essentially all test objectives were met or exceeded. The thick middle member (7.0 m) of the G seam was gasified. The burn was accomplished using both air injection and steam/oxygen injection. Product gas quality varied from 4.7 to 7.1 MJ/m/sup 3/ with air injection, and from 8.3 to 11.4 MJ/m/sup 3/ with steam/oxygen injection. The post-burn cavity definition study showed that the burn zone was partly filled with thermally altered rubble, with a water-filled void space at the top of the burn zone. Test 2 was conducted from August to November 1981. The burn was made in a longer and deeper module than that used in the first test; the base of the Test 2 module was at approximately 188 m true vertical depth. The total energy produced was approximately 1.6 x 10/sup 14/ J, from gas of an average heating value of 13.2 MJ/m/sup 3/. Data from the post-burn study, as well as data from the test, indicated that the ''firepit''mechanism, or coal falling from the upper face and walls of the burn zone into a firepit area near the injection well, occurred in the test. The test site was deactivated in 1982. By the end of Phase IV on September 30, 1982, no measurable subsidence over either burn site had been observed. Tests of groundwater quality showed only minor changes in composition. Monitoring of the groundwater and overburden were scheduled to continue for 4 to 5 years. Appendices A and B containing test data are available on microfiche only. 17 refs., 18 figs., 12 tabs.