SIERRA DE V IN ALES 235 



of the northern system (the Costanera), but the 

 folding upward of the two was certainly contem- 

 poraneous. All of the mogotes of the Viiiales 

 valley, including the large Tumbadero, the Dos 

 Hermanos, and the many smaller ones scattered 

 about the valley floor are clearly but fragments of 

 the main sierra now wholly detached and isolated 

 by erosion. The ammonites, which Dr. Torre 

 has been collecting for several years, come prin- 

 cipally from the rocks of this southern range and 

 indicate a probable Jurassic origin of the limestone. 

 As heretofore noted, the mogotes about ''Kilometer 

 14" do not belong to the Vifiales range, but to- 

 gether with the Cerro de Cabras hills farther west, 

 represent either remnants of a third line of Jurassic 

 sierra that once followed a course parallel with 

 the existing ranges, or possibly a later Tertiary 

 deposit upon the flanks of the older mountains. 

 We lacked sufficient data to determine this ques- 

 tion. The westward extension of the Sierra de 

 Vifiales is locally known as "La Penitencia" 

 or "Sierra del Infierno," two names well chosen 

 in the opinion of anyone who attempts to climb 

 the talus to reach the walls above. 



To surmount this talus was our program for 



