EASTERN ANDES: CORDILLERA VILCAPAMPA 221 



points the schists assume a darker hue and take on the characters 

 of a rather typical mica schist. 



It is probable that the Vilcapampa intrusion is one of a family 

 of batholiths which further study may show to extend over a 

 much larger territory. The trail west of Abancay was followed 

 quite closely and accidentally crosses two small batholiths of 

 peculiar interest. Their limits were not closely followed out, but 



s 



Fig. 146 — Deformative effects on limestone strata of the granite intrusion on the 

 southwestern border of the Vilcapampa batholith above Chuquibambilla. Fig. 147 is on 

 the same border of the batholith several miles farther northwest. The granite mass 

 on the right is a small outlier of the main batholith looking south. The limestone 

 is Cretaceous. See Appendix C for locations. 



were accurately determined at a number of points and the remain- 

 ing portion of the contact inferred from the topography. In the 

 case of the larger area there may indeed be a connection west- 

 ward with a larger mass which probably constitutes the ranges 

 distant some five to ten miles from the line of traverse. 



These smaller intrusions are remarkable in that they appear 

 to have been attended by little alteration of either invading or 

 invaded rock, though the granites were observed to become dis- 

 tinctly more acid in the contact zone. Space was made for them 

 by displacing the sedimentary cover and by a marked shortening 

 of the sedimentary rim through such structures as overthrust 

 faults and folds. The contact is observable in a highly meta- 

 morphosed belt about twenty feet wide, and for several hundred 

 feet more the granite has absorbed the limestone in small amounts 

 with the production of new minerals and the development of a dis- 

 tinctly lighter color. The deformative effects of the batholithic 

 invasion are shown in their gross details in Figs. 141, 142, and 146 ; 

 the finer details of structure are represented in Fig. 147, which is 

 drawn from a measured outcrop above Chuquibambilla. 



It will be seen that we have here more than a mere crinkling, 



