"Application of the in situ recovery process to oil shale was tested during two field experiments near Rock Springs, Wyoming. The results of these tests demonstrate that a self-sustaining combustion zone can be created in an oil shale body, that this zone can be moved through the oil shale, and that the process will produce shale oil. Evaluation of the combustion process by monitoring produced fluids for physical and chemical properties and volumes is described. The material and energy balance obtained in compared with a second evaluation based on extensive coring of the test area after the test was terminated. Several side results of the research are noted such as ground surface heating by underground burning and production of low- to medium-Btu gas during retorting."