Oil yields, lithology, and stratigraphy have been evaluated for 15 cored wells and two sampled wells representing 10 square miles of the Tipton member of the Green River Formation near Green River, Wyoming. The area evaluated is being used by the Bureau of Mines for experimental production of oil from the oil shales in place. Lithology and oil yields were correlated to produce a stratigraphy diagram for the in situ study area, permitting precise designation of comparable sections. Oil yields from eight cores and two sets of drill-cutting samples within a quarter section show the range of variation in average oil yield arising from experimental error. No difference in oil-shale richness across the study area is indicated. Average oil yields for three Tipton sections in the study area were determined as follows: (1) the entire Tipton member oil shale (about 145 feet thick), 13.3 gallons per ton; (2) the 40-foot upper rich zone, 21.0 Gallons per ton; and (3) the 21-foot zone in which the Laramie Energy Research Center is conducting in situ experiments, 22.4 gallons per ton. One acre of the 21-foot experimental section represents 34,300 barrels of oil in place, and 1 acre of the Tipton's 40-foot rich upper layer represents 62,000 barrels.