On Plate XX of Bulletin 46 of the Oklahoma Geological Survey,(FOOTNOTE 1) broken lines indicate the supposed course (inferred from reconnaissance observations) of the outcrop of various resistant members of the Hoxbar formation from the vicinity of Ardmore southeastward to the type locality of the formation. Later, more complete mapping has revealed some errors in that map, particularly with respect to the lower members of the formation, which through a considerable portion of that distance are concealed by alluvium of the West Fork of Anadarche Creek and of tributaries thereto. A corrected map of the Hoxbar members south of Ardmore is submitted herewith (Fig. 1).

During 1932 and 1933 the Gypsy Oil Company and the Schermerhorn Oil Corporation cooperated in mapping the area in question in complete detail by plane table for future sampling of the Hoxbar and Deese formations, which are here developed in maximum thickness (approximately 11,000 feet in the aggregate) and occur in simple homoclinal position with few local structural complexities.

The principal reason for undertaking such detailed mapping at this time, in an area so nearly devoid of oil possibilities, was the plan then beginning to materialize for the construction of a dam 150 feet high near the southeast corner of Sec. 14, T. 6 S., R. 2 E., Love County, Oklahoma, across the gorge cut by Anadarche Creek through the Devil's Kitchen member of the Deese formation, which would impound about 10,000 acres of water, covering a large part of the area in question. This project was definitely espoused by the last legislature of Oklahoma, which appropriated $90,000.00 for the purchase of land in and bordering the proposed Murray Lake.

The geologic field work was done under direction of M. P. White and the writer, by W. Morris Guthrey and Charles A. Milner, who also prepared the final map on a scale of 800 feet to the inch. As the complete map measures 42×74 inches, it has not been practicable to publish it; but copies have been made available on request for use by other geologists, and a copy has been filed with C. E. Decker, curator of publications of the Oklahoma Geological Survey at the University of Oklahoma, at Norman. A similar map has been

FOOTNOTE 1. C. W. Tomlinson, "The Pennsylvanian System in the Ardmore Basin," Oklahoma Geol. Survey Bull. 46 (1929).

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Fig. 1. REVISED MAP OF OUTCROPS AND CORRELATION OF RESISTANT MEMBERS OF THE HOXBAR FORMATION SOUTH OF ARDMORE, OKLA BY C. W. TOMLINSON

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prepared of the area of Pennsylvanian rocks east of Berwyn and north of Washita River, where there are exceptionally fine exposures of many of the highly fossiliferous members of the Dornick Hills formation, and of the lower Deese, affording excellent opportunity for collecting.

According to the revised mapping, the Confederate limestone member, described in Bulletin 46 as the basal unit of the Hoxbar formation, is traced southeastward into instead of below the Westheimer member as mapped west of Hoxbar, near the south line of Carter County. As the Westheimer is still believed to have been correctly correlated between the four areas in which it was identified on Plate XX of that bulletin (the Hoxbar area, the Pleasant Hill syncline northwest of Overbrook, the syncline just south of Overbrook, and south of the Criner Hills), this name can now be dropped and the name Confederate (geographically preferable) be substituted.

This places the base of the Confederate limestone member in the type area of the Hoxbar formation slightly higher than the base of that formation as originally mapped by Goldston.(FOOTNOTE 2) However, as this member is in that area the lowest of the conspicuous limestones which here constitute the most essential distinguishing characteristic of the Hoxbar formation as compared to the formations above and below it, and also includes the lowest limestone conglomerate (possibly intraformational) above the Bostwick member of the Dornick Hills formation, it appears most appropriate to continue to regard the base of the Hoxbar as coincident with the base of the Confederate limestone member.

The detailed mapping has revealed 15 distinct limestone or sandy limestone members of the Deese formation, some of them very fossiliferous; but thick massive sandstones and chert-pebble conglomerates remain the outstanding conspicuous lithologic types most characteristic of the Deese outcrops.

A corollary of the correction in mapping of the Confederate member is the identification of the Union Dairy member of the Hoxbar formation with the Crinerville limestone member, which in Bulletin 46 was not positively identified southeast of Ardmore. As the name Crinerville has been in current use for many years with definite geographic significance, it is to be preferred to the name Union Dairy, which has never been in general use as a geographic name, and is therefore dropped.

It is reported by White (FOOTNOTE 3) and others that unpublished microscopic paleontological data confirm this correlation of the Union Dairy limestone with the Crinerville limestone member of the Hoxbar.

Similar detailed mapping has not yet (at time of writing) been extended to cover the area north of Ardmore. Positive identification therefore has not yet been made of individual members of the Hoxbar there. Even the Arnold member of the Deese, so well developed in the type area northwest of Ardmore, has not been traced around the Caddo anticline into the Berwyn area. The member marked as Arnold on Plate XVIII of Bulletin 46 in Sec. 15, T. 3 S., R. 2 E., has been traced south-southwest into a position stratigraphically much higher than the member so marked in Section 28 of the same township; therefore the broken line connecting the two on that plate should be disregarded. The upper of the two is probably the true Arnold.

FOOTNOTE 2. W. L. Goldston, Jr., "Differentiation and Structure of the Glenn Formation," Bull. Amer. Assoc. Petrol. Geol., Vol. 6, No. 1 (January-February, 1922), pp. 5-23.

FOOTNOTE 3. M. P. White, oral communications.

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