12 University of Texas Bulletin 



ison and Bennington they thicken rapidly ; so that by inference the main 

 thickening is ENE. and the lines of equal thickness run about 60 E. of N. 



Southward from the Red River in Cooke County the Weno and Pawpaw 

 formations thin gradually to at least the Colorado River where they are 

 probably represented by strata lying near the top of the Georgetown lime- 

 stone. The two formations behave very differently over the area men- 

 tioned. The Weno formation, south of the change of direction of its out- 

 crop in Cooke County decreases slightly in thickness, from about 75 feet 

 near Gainesville to 65 feet near Fort Worth, 60 near Riovista, 40 near 

 Waco, and 20(?) near Georgetown. The Pawpaw clay on the other hand, 

 thins more rapidly from the Red River southward. Near Cedar Mills, 

 Cooke County it is 60 feet thick, in Denton County 40 feet, at the north 

 border of Tarrant County 27 feet, on Sycamore Creek near Fort Worth 24 

 feet, at the south border of Tarrant County 12 feet, at Riovista 5 feet, at 

 }Blum 3 feet, and near Waco about 2 feet thick. This thinning is a part of 

 the general thinning southwards of the softer formations of the North 

 Texas Washita, which south of the Brazos are represented in the George- 

 town limestone, as is observable in the Kiamitia marl, Duck Creek marl, 

 Denton marl, Pawpaw clay and Grayson marl. The alternate harder for- 

 mations, the Duck Creek limestone, Fort Worth limestone, Weno limestone, 

 Mainstreet limestone, undergo proportionately less thinning southwards 

 and hence contribute relatively larger components to the Georgetown lime- 

 stone. 



There are equally distinct differences of lithology and facies, which are 

 presented later. 



The present paper is only an introduction to the large and interesting 

 Weno and Pawpaw faunae, the majority of whose species are still unde- 

 scribed. Much collecting and further study is required before any attempt 

 can be made towards a monographic treatment of these fossils. It will be 

 noted that the limits set in this paper coincide with the boundaries of hori- 

 zons 25 to 33 inclusive, of Adkins and Winton's preliminary section of the 

 North Texas Washita division. 1 



1 Adkins and Winton, Paleontological Correlation of the Fredericksburg and Washita 

 Formations in North Texas. Univ. Texas Bull. 1945, 1920. 



