My 
Chis 
Mö 
SS 
| 
S 
FEY 
UG 
fa 
DETRITIC FORMATIONS 69 
der and also figured in a somewhat 
schematized manner (1897). Over the 
crystalline basement, which forms, as 
mentioned, a SE-dipping basal plane, 
there lies with the same dip (45°— 
30°) a mighty series of continental 
Strata of different colours. This series 
continues along the southeastern side 
of the mountain (see later on), forming 
here a steep-dipping mantle. The whole 
series sinks rapidly beneath quaternary 
accumulations in the south, but far- 
ther in this direction it rises again in 
the great anticlinal upward bend of 
the Cerro Bola, as Bodenbender 
has already stated (1911). 
The basement of the profile is com- 
posed of mica and amphibolite schists 
penetrated with red pegmatitic granite. 
The schist rocks have a slight north- 
ward dip contrasting with the steep 
inclination of the schists in all other 
parts of the Cerro Villa Union. This 
circumstance may be explained as a 
simple block tilting of the basement 
part lying under the sediment cover. 
The degree of the tilting is already 
evident from the dip of the strata. 
Regarding the lithology of the strata, 
UG: upper Gondwana red sandstones and coarse grained arcoses. V: volcanic agglomerates. 
at the base there is a conglomeratic 
layer, composed of quite heavy boul- 
ders of angular forms from the same 
rocks, that occur in the basement. The 
Fig. 7. A natural profile along the western side of the Cerro Guandacol (southern end of the Cerro Villa Union), seen from the Guandacol valley, 
ome miles distant. To the extreme left (crosses) the crystalline basement. Ti: tillite. LG: lower Gondwana sandstones and shales. T: tuff layer. 
