The lack of rapid, but geochemically sound, methods for identifying organic-rich rocks in small samples (potential petroleum source rocks) was a major obstacle to the application of petroleum origin and migration concepts in oil and gas exploration. More than 4,000 ft of near-surface stratigraphically continuous core, primarily shales, was obtained from the marine Cretaceous of central Wyoming by use of a variety of geologic,

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mineralogic, paleontologic, petrophysical, and geochemical techniques. Extractable heavy hydrocarbon and organic carbon contents were used as standards to which the other techniques were compared. It was found that lithic characteristics, particularly sedimentary structures and thin-section properties, correlate quite well with the standards. Test-tube pyrolysis, followed by careful measurement of the amount of fluorescence produced by the condensed liquids, was the most useful method developed.

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