the Lower Pecos Valley, New Mexico. 417 



Age Formation Thickness Lithologic Character 



capping mesas, lying uncon- 

 formable upon the Red- 

 beds. 



Cretaceous Sierra Blanca 1500-2500 Coal seams, interbedded 



Series sandstones and shale and oc- 



casional thin limestone 

 with a massive, coarse- 

 grained, buff sandstone near 

 base (Dakota?) This series 

 is sometimes found under- 

 lain by variegated shales, 

 thin beds of limestone, sand- 

 stones and conglomerates; 

 • presumably the Morrison 



formation. 



Permian 



Red-beds 



(Gypsum series) 



700 Red shales and sandstones 

 with occasional thin beds of 

 gypsum. 



300 Massive white and reddish 

 beds of gypsum with alter- 

 nating red shales and sand- 

 stones, giving rise to a solu- 

 tion type of topography with 

 sink holes, sometimes filled 

 with water (Bottomless 



Permian 



San Andreas limestone 650 



Massive layers of compact, 

 grayish, fossiliferous lime- 

 stone with occasional layers 

 of shale and sandstone. 

 Massive coarse-grained fri- 

 able buff sandstone near 



Local Unconformity. 

 Pennsylvanian Yeso 



Pennsylvania!! Abo 



1000 Red shales underlain by al- 

 ternating reddish shales, 

 limestones and layers of 

 gypsum. Highly folded 



where exposed in the vicinity 

 of Capitan Mountain. Base 

 unexposed. 



800 ± Exposed near Alamogordo. 

 Alternating red sandstone 

 and red sandy shales. 



Pennsylvanian Magdalena Group 1500-2000 

 (Madera limestone) 



Exposed near Alamogordo. 

 Massive bluish gray and 

 dark bituminous limestone. 



Areal Geology. 



Magdalena Group. — The Magdalena group as exposed 

 toward the foothills of the Sacramento Mountains near 



