Plate XXI 



6 ' 



;^MM'^,.... ■ 



Fig. 1. — Orthophragmina Sandstone of Tepetate Formation, Arroyo Colorado, 



ABOUT 1 KILOMETRE S.W. OF EaNCHO EL TEPETATE, SEEN FROM S.E. Nos. 4-7, See text. 



Fhot. Am. Ifeim. 



Fig. 2. — La Ventana, Aeeoyo Cadegomo, seen from N.E. The rock to the left, above 

 the unconformity, consists of marine conglomerate (Pliocene) ; below it is the folded 

 Ventana shale (Monterey shale). 



To face p. 5?9.] 



