PEESIDIO DEL NORTE TO SAN VINCENTE. 



59 



gravelly table-land, forming along the line of strike open valleys. Arid and bleak sterility 

 characterizes this formation, to which the scant and sandy bottom-laad is hardly an exception. 

 Fossils are occasionally copiously imbedded in tliese ledges ; among which principally Ostrea, 

 Ammonites, and Turrifella occur, and show that the formation belongs to the upper cretaceous 

 series. At some points there is an evident approach to the lower Tertiary formation. 



VIEW OF PHESIDIO DE SAN VI.NCFATE AND SIERRA CARMEL. 



The eastern limits of this basin are marked by the extensive and elevated range of the Sierra 

 Carmel, presenting directly in front an unbroken wall composed of a light-colored limestone. 

 This shows a dip to the east. Its western aspect exhibits a line of perpendicular escarpment 

 rising in several peaked knobs to a great height. The line of mountain wall thus exposed 

 presents a series of terraced elevations, dividing horizontally the abrupt face of rock exposure. 



Along these terraced lines, and associated with the talus there accumulated; is a growth of 

 dark-green shrubbery, strongly contrasting with the ochreous-colored wall, which forms the 

 background. 



This mountain range further to the southeast exhibits an extensive development of igneous 

 rock, showing in the distance a very rugged outline. 



The occurrence of these several ranges forces the river from its east and southeast course, and 

 gives it an abrupt turn to the north. The mountain barrier is thence passed at a lower eleva- 

 tion of the main range forming the Carmel canon. The river here cuts through the limestone 

 strata, showing a distinct dip to the northeast ; after a course of 8 miles, the river emerges on 

 the eastern slope of the Carmel range. To accomplish the same distance with our mule train a 

 detour of 40 miles was necessary, leading again to tlie river at the point where it emerges from 

 the mountains. The operations of the surveying party being here suspended, our route hence 

 led southward to the Mexican settlement of Santa Rosa, thence to Eagle Pass. 



