LOWER CRETACEOUS SERIES. 729 



On every side the rocks dip away from the mountain, except at the south 

 end, immediately north of Quitman Pass, where at least four thousand feet 

 of rock has been sheared abruptly across the strike by the eruptive porphyry 

 and granite. From Quitman Pass southeastward to the Kio Grande Creta- 

 ceous rocks form the body of the mountains, rising near the central point to 

 a height of nearly one thousand feet above the basin. 



The same conditions of the rock and character of topography exist in South 

 Quitman Mountain as were found in Devil's Ridge and in other exposures, ex- 

 cept those of Malone Mountain. With the exception of a small area on the 

 southeast side of Quitman Pass, where a part of the strata is inverted by the 

 excessive igneous action, the rocks dip to the south westward with a general 

 strike of north 30° west. 



The eastward facing mountain side is precipitous and bluffy, while the 

 southwest side is rolling, with a more gradual descent to the Rio Grande 

 basin. 



The bluff series is succeeded by an extensive development of false laminated 

 calcareous shell brecciate sandstone, which shows a return to shallow water 

 deposits, calcareous fossiliferous sandstones, thinly-bedded and flaggy and 

 having a depth of two hundred and fifty to three hundred feet. 



The fossiliferous sandstone underlies a band of shell brecciate limestone, 

 which is in turn succeeded by a fourth and final Caprotina horizon sixty feet 

 thick. The Caprotina horizon is considered the limit of this series. 



SECTION OF QUITMAN BED ACROSS THE MOUNTAIN AT QUITMAN GAP. 



1. Massive Caprotina limestone 60 feet. 



2. Thickly -bedded siliceous shell limestone 20 feet. 



3. Calcareous flaggy and yellow friable sandstone containing large Exogyra 



and oblong fan-shaped oyster resembling 0. owenana 250 to 300 feet. 



The fourth and final Caprotina horizon is considered the limit of the Quit- 

 man series. The transition from the third Caprotina horizon into the arena- 

 ceous horizons, and from this horizon into that of the fourth Caprotina, is 

 very abrupt, from massive deep sea limestone up into a near shore sand, 

 and then down again into a comparatively deep sea limestone. 



Near the center of the arenaceous horizon are numerous very large oysters, 

 an oblong thick-beaked oyster, Pecten, and a peculiar TrigoniaAWe fossil. 

 The oblong oyster ranges almost throughout the sand. 



The transition from the sand upward into the fourth Caprotina horizon is 

 through twenty feet of finely comminuted shell limestone. 



The fourth Caprotina horizon resembles that of the third in the character 

 of rock, and it carries the same fossil in great numbers, forming in part the 

 mass of the rock. 



