COROCORO COPPER DISTRICT OF BOLIVIA 49 



as high as 85 and the Vetas are flatter along the fault 

 plane, but the exposures here are not so good as those 

 farther north. In the mines the fault plane shows a very 

 steep westerly to vertical dip. 



The observations prove beyond question that the fault 

 plane has a steep westerly dip greater than the normal dip 

 of the Vetas. With respect to the direction of movement 

 along the fault plane the evidence is not unequivocal, some 

 exposures indicating that the Vetas have been pushed over 

 the Ramos, others that the Vetas have slipped down over 

 the Ramos. Hence the structural evidence along the fault 

 does not permit of a definite conclusion with respect to the 

 relative stratigraphic position and age of the two series 

 of rocks. 



The fault plane is the only line of contact between the 

 Vetas and Ramos in the area investigated. Hence there are 

 no other structural features that might aid in solving the 

 problem, and we are brought back to the paleontologic 

 evidence that both series are of nearly the same age with 

 the probability that the Ramos are the younger. 



THE DESAGUADERO SERIES 



Capping the Cerro Corocoro and extending to the south 

 and southwest in the direction of Tarejra is a third series 

 of rocks. They seem to continue far to the west, to the 

 Desaguadero River and beyond, and for that reason we are 

 calling them the Desaguadero Series. They differ from the 

 Vetas series in nearly lacking the coarse clastic materials 

 which are so prominent in the latter and in the absence of 

 the gray sandstones and conglomerates. They differ from 

 the Ramos in the absence of gypsum beds and stringers. 

 They differ from both the Ramos and Vetas in the lack of 

 the copper mineralization of those rocks. They are like the 

 Ramos in the dominence of the red-colored beds and the 

 fine-grained character of the sandstones and for that reason 

 doubtless had previously been assumed to represent that 

 series. 



