Discusses the mineral associations in shales from an alternating series of late Jurassic sandstones and shales containing several zones of bituminous schists. The fine fractions of 13 samples of shales from different lithologic subdivisions were found to be similar, being essentially montmorillonitic, with minor amounts of illite and occasionally kaolinite. Analcime was identified in several samples; its occurrence in a predominantly montmorillonitic rock suggests that the original rock was volcanic in origin.