304 R. T. HILL — GEOLOGY OF RED RIVER. 



has been given. This limestone, by chemical induration, has at places 

 assumed the hardness of marble, taking a handsome polish. This in- 

 duration is superficial, however, for at other places away from the surface 

 it is soft and pulverulent. The limestone occupies the bluff of a north- 

 ward-facing escarpment from Emmet, Chickasaw Nation, eastward to 

 Goodland, Choctaw Nation, and finally disappears in the flood-plain of 

 Little river, five miles east of the Arkansas line. It also outcrops in 

 Grayson county, Texas, about two miles south of the historic geologic 

 locality of Old Preston, and forms the south bluff of Red river valley. 



The Walnut clays and the Goodland limestone together represent the 

 greatly attenuated northern beds of the Fredericksburg division, which 

 has a constantly increasing thickness southward. The limestone is the 

 northward continuation of two upper calcareous members of the Fred- 

 ericksburg division (the Caprina limestone and Comanche peak chalk) 

 south of the Brazos, but I shall continue to use the local name for this 

 bed where it represents this consolidated phase. 



The Goodland limestone contains the following characteristic Fred- 

 ericksburg species : Cyphosoma, sp. ; Eaallaster texanus, Roemer ; Gryphsea 

 navia, Conrad (not of others) ; Rostelaria, sp. ; Cerithium bosquensis, Shu- 

 mard (i. e., Chemnitzia occidentale, Gabb), and Sphenodiscus roemeri, Cragin. 

 The remarkable aberrant Chamidse and Rudistse so well developed in 

 synchronous and deeper beds to the southward are missing. 



Beds of the Washita Division. — Succeeding the Goodland limestone are 

 the basal Kiamitia clays of the Washita division, forming'a prairie region 

 sloping away from the Goodland escarpment. These clays are succeeded 

 in turn by the other members of the Washita division of the Comanche 

 series, which are described more minutely on page 324. All these beds, 

 with one exception, are calcareous and outcrop as prairies. The North 

 Denison sands is a terrane of unconsolidated sands, and like the Trinity 

 and Dakota its outcrop is invariably covered with timber. 



Lower Cross Timber {or Dakota) Sands. — Capping the uppermost bed of 

 the Washita division (the Main street limestone) unconformably, the 

 Dakota sands constitute two intensely arenaceous and ferruginous belts 

 of country, forming low timbered hills in that region. I have previously 

 defined these beds as the Lower Cross Timber sands, while Doctors B. F. 

 Shumard and C. A. White have correlated them with the Dakota.* 



These sands are unconsolidated except in their basal portion, where 



* The brothers Shumard made several publications on the region treated in this paper, but com- 

 pletely misinterpreted the stratigraphic sequences of the beds, and in some cases referred them 

 to the Tertiary system. The Third Annual Report of the Geolo2:ieal Survey of Texas used Dr B. F. 

 Shumard's terms of Red River group, originally applied to many beds, for this terrane. It is grati- 

 fying to note that Mr Taff abandons this untenable position in the second part of his report in the 

 Fourth Annual, and besides gives most valuable details of the stratigraphy of the Dakota and Eagle 

 Ford beds, which, with the Denison beds, in part constitute Shumard's old Red River group. 



