Detailed field work during the summer of 1938, and subsequent insoluble-residue studies, have yielded considerable additional data on the character of the Morrow group of rocks in Adair County, Oklahoma. Sufficient information is at hand to permit the recognition of the divisions of the Morrow group, the Hale sandstone at the base and the Bloyd shale above. In addition, the Brentwood and Kessler members of the Bloyd are developed in Adair County. The Brentwood can be recognized as an interval of alternating shale and limestone beds, and the westward extent of the Kessler has been determined to be about 4 miles west-southwest of Stilwell, Oklahoma. Only by insoluble-residue studies is it possible to differentiate between the limestone beds of the Hale formation, and the Br ntwood and Kessler limestone members. The Kessler member, in particular, has a diagnostic insoluble residue.

There is a marked disconformable contact between the Pitkin limestone and the Hale sandstone in almost every section measured and studied. In all but a very few cases this contact consists of a highly ferruginous, calcareous, conglomerate bed averaging less than a foot in thickness. It is invariably phosphatic.