The large block experiments were a series of five, medium-scale in situ coal gasification parameter study tests. Two injection flow rate schedules and two steam/oxygen ratios were used. The final experiment was a test of the effect of roof interaction and of the controlled retracting injection point (CRIP) system. At the conclusion of the test series, each burn cavity was carefully excavated. The burn cavities were filled mostly with rubble and thermally altered coal. Photographing, geologic examination, and chemical analysis of selected samples were used to document the excavation results.