20 SIERRA DE UMANGO 
very probable, that the Umango schists are homotaxial with the 4 | 
Famatina schists. | | 
The great limestone banks in the Umango area are met with 
principally on the western side, in the Cerro Cacho and on the 
lower mountains between her and the Sierra de Umango ridge. By 
studying the map recently worked out by Rassmuss illustrating 
the Precordillera of the province of La Rioja, one becomes convin- 
ced, that the Umango limestones once formed the northward con- 
tinuation of the mighty lower silurian zones of the said mountain 
chain. Therefore, the Umango limestones may be of lower silurian 
age too. The circumstance, that the later are strongly metamor- 
phosed and contorted, whilst the limestone masses of the Precor- 
dillera are unmetamorphosed, does not form any obstacle to the 
presumption, and may be explained by the possibility, that the 
Umango is forming another structural element in respect to the 
Precordillera. 
Studying the report and map of W. Penck (1920) from the wes- = = 
fern part of the province of Catamarca, to the north and northeast 
from the Umango area, one will find that the intensely folded, 
banded and, metamorphosed structure of the Sierra de Umango 
continues NE- and NNE-ward under the floor of the Jaguel bol- 
son far into the mountains of the western part of Catamarca, an 
area lying to the west of the valley of Fiambalä. To the east the 
Catamarca structure is bounded by a granite area, corresponding to 
the Famatina batholith (which also forms the eastern margin of the 
Umango structure). The Catamarca structure may be of lower pa- 
laeozoic age! and undoubtedly it is of the same as the Sierra-de- 
Umango-element. The limestone is there, however, completely 
lacking. 
1 Penck has expressed the opinion, that it is of devonian age, but while fos- 
sils are also here lacking, this statement is of no definite character. Nevertheless, 
no doubt, it is palaeozoic and of pre-Gondwana-age at least (see later on page 61). 
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