LOWER CRETACEOUS SERIES. 719 



The Caprina limestone, besides forming the cap rocks of Flat Mesa and 

 the scarp four miles north of Flat Mesa, forms the crest of the hill one mile 

 southwest, and extends into the basin two miles southeast of Sierra Blanca 

 Station. 



It pitches into the basin on the west side of the laccolitic uplift at the ex- 

 treme northwest part of Flat Mesa. It also appears jutting against the side 

 of Sierra Blanca Peak, seventeen hundred feet below the summit, and out- 

 cropping from the base of the peak for one mile in the direction of Sierra 

 Blanca Station. 



WASHITA DIVISION. 



FIRST CAPROTINA BED. 



The first and lowest Caprotina horizon appears here immediately succeeding 

 Caprina limestone, without apparent change in the rock. 



The Caprotina limestone is about twenty feet thick, and the fossil occurs 

 principally near the lower edge, where it is abundant, filling the limestone in 

 mass. It is found where the rock is exposed at the localities named for the 

 occurrence of the Caprina bed. 



At the southeast side of Eagle Mountain, near Finney's Ranch, there is a 

 horizon of Caprotina limestones that has been correlated with this first Cap- 

 rotina horizon in Flat Mesa by a parallel section at Finney's Ranch. (See the 

 two foregoing sections.) 



ARIETINA BED. 



The exact connection between the Arietina bed and the underlying Capro- 

 tina limestone is not very clear, as but one link in the chain of facts that may 

 be had was found. 



Near the centre of the northeast side of Flat Mesa, where a fault of one 

 hundred and sixty feet has thrown the rocks down to the northward, number- 

 less individuals of a foraminifera, Nodosaria texana, are exhibited in a hori- 

 zon of flaggy siliceous limestone that lies directly above the Caprotina lime- 

 stone. These same flags, or flags very similar, with the same foraminifera 

 associated with Exogyra arietina and a small gryphea, occur in some small 

 hills on the north side of Quitman Mountains, at the Southern Pacific Rail- 

 way. Immediately under these flags is a massive granular limestone whose 

 structure is completely destroyed by the local metamorphism caused by the 

 contact granite. It is pretty evident that this massive limestone is the first 

 Caprotina bed. 



1 include in the Arietina bed two horizons, having a total thickness of some 

 forty-five feet. These horizons are in the order: First, the Arietina flags 



