The succeeding 18 feet consists of grayish sandy shale with layers of fine grained gray or yellow sandstone an inch thick. Above is 40 feet of purplish-black shale like that at the base, succeeded by 15 feet of drab clay. About 110 feet above the base is a bed of friable fine-grained, achre-stained sandstone 18 inches thick, overlain by a few feet of light brown clay. The uppermost 25 feet consists of paper-thin layers of purplish-black shale with gypsum filled cracks. The member attains its maximum thickness near Colorado City where it is 145 feet thick, but in the southern part of the quadrangle it is much thinner and in places measures less than 10 feet. Dakota - Shows Dry Creek Canyon member present in Bear Creek section - which must be good'. Richardson (1915) - Recognizes Purgatoire and its members in Perry Park. Does not separate members as 'exposure' too poor. Glencairn equivalent apparently chiefly shale as at type. Stose, (1912) Purgatoire formation. - The Purgatoire formation, (p. 3) which is composed largely of sandstone, was formerly regarded as part of the Dakota sandstone and is so 68