878 E. T. DUMBLE — CRETACEOUS OF TEXAS AND MEXICO. 



Feet. 



Comanche Peak and Exogyra texana stages. — Thin bedded, marly hme- 

 Mort. ; yellow to blue in color. Exogyra texana, Roem. ; Gryphsea pitcheri, 

 stones, Ostrea crenuUmargo, Roem., etcetera. Arboles mountains 120-150 



Glen Rose stage. — Thin bedded, marly limestones underlaid by heavy 

 bedded limestone, with interbedded marly shale. Requienia texana, 

 Roem.; Pleurocera strombiformis, Schlot. {Vicarya branneri, Hill) ; Natica, 

 Exogyra and Gryphssa of undetermined species. Arboles mountains. 

 Base not seen 300- (?) 



This is the only Mexican area which I have had an opportunity of ex- 

 amining. Other details of the section will be given below in connection 

 with those of various Texan localities. 



Lower Cretaceous. 

 / 



BOSQUE DIVISION. 



Its Members. — The Trinity sands, Glen Rose or Alternating beds and 

 Paluxy sand, which constitute the three members of the Bosque division 

 at the typical locality,* have only been found together in west Texas, in 

 the vicinity of Sierra Blanca Junction. At all other localities one or two 

 of these members are missing. 



Flat Mesa Section. — The section of Flat mesa, beginning one mile north 

 of the Junction, gives : 



Feet. 



Paluxy stage. — Brown quartzitic sandstone ^. - 35 



Silicious conglomerate and grit 10 



Brown sandstone 46 



Alternating stage. — Arenaceous limestone, with Actxonella dolium, Roemer, and 



a small Exogyra 4 



Trinity stage.— Brown quartzitic sandstone, exposed 100 



This section is repeated in the hills just south of the Junction, with 

 interstratal sheets of rhyolite and extrusions of porphyry. 



Kent Section. — In the section made at Kent (which corresponds in this 

 respect with the sections made at the southeast point of the Llano Esta- 

 cado and at Double mountain) we found no trace of the Alternating 

 beds and only one stratum of sand, which is therefore referred to the 

 Paluxy, because, as Taff has shown, at no place has the Fredericksburg 

 been found resting directly on the Trinity. This sand, at Kent, rests 

 unconformably on a semicrystalline limestone, presumably of Permian 

 age. It contains the largest amount of silicified and opalized wood which 

 I have found in Texas, and it may be that a study of this would decide 

 whether the sand is altogether Paluxy or whether it includes both Paluxy 

 and Trinity. 



=i=TaflF: Third Ann. Rep. Geol. Survey of Texas, p. 301. 



