116 SIERRA DE UMANGO 
c) THE DEVELOPMENT OF THE ACTUAL RELIEF. 
The network of the lines of vertical dislocations. 
After the deposition of the above described coarse conglomerate, 
probably covering considerable areas, the ground of the area was 
affected by strong uplifting movements, causing, as known, the ac- 
tual alpine relief of the whole Cordilleran chain and of all the 
pampean sierras. These movements went in the Umango area as 
everywhere else along vertical or steeply dipping slide or fault pla- 
nes, running in different directions. 
Along these lines of dislocation the cover of the continental 
sandstones sunk down with accompanying tilting of the strata and 
with formation of flexures or by a simple crosscutting of the layers, 
so that their edge lies directly against the crystalline fault wall in 
a more or less horisontal position. It is therefore quite simple to 
determine the position of the dislocation lines: these are represen- 
ted by the limit between crystalline floor ground and clastic rocks, 
in the topography marked by a more or less abrupt slope. On 
the accompanying map of the Umango area the principal lines 
have been fixed. 
According to the statements above it is evident, that all the lo- 
wer areas really must be occupied by sunk parts of the continental 
sediments, while the greater elevations are composed of the crys- 
talline ground. ‚These elevations are but very exceptionally capped 
by the uplifted parts of the sediments, since almost all of them 
have been destroyed by erosion. 
A short description of sunk parts of the sediment cover, that is, 
the tectonical valleys and lowlands, will follow in the next pages. 
Description of the sunk (down faulted)} areas. 
The Vinchina valley. 
As mentioned, the Sierra de Umango topographical complex is 
very markedly separated from the Famatina ridge to the east by 
the deep broad and long Vinchina valley running from the moun- 
