112 SIERRA DE UMANGO 
an earlier phase than the below described vertical dislocations, by 
which the actual relief was formed. 
a 
A ATNTIL ZOG CX 
Ö 
N 
IT 
Fig. 18. Profil through the western border of the Pirca zone; Over-thrust of a crystalline 
block (CX) over a red sandstone. Length of the block ab. 300 m. The arrow indicates the 
direction of the overthrust. 
In the Precordillera of Guandacol these tertiary movements have 
caused many complicated tectonical features in the permian struc- 
ture, as is evident from the investigations by Rassmuss (1916). 
The disturbances described above concern only the continental 
sediment-area series. But also the crystalline basement has been 
Fig. 19. By -overthrust folded sandstone beds resting on the surface of the crystalline Basement 
(the thrust, plane). Northern end of the Cerro La Pampa and eastern border of the ,intermontane 
zone“. Looking south. 
