DETRITIC FORMATIONS | 17 
series of red and brown sandstones of apparently triassic age. These 
last named strata form the very bulk of the Cerro Punta Colorada, 
as the name also shows. In the profile of the Quebrada Banda 
_ Florida only the red triassic strata are visible. They rest directly 
_ upon the crystalline basement, a circumstance met with in some 
~ other parts of this area too (fig. 11). This lack of the lower Gondwana 
_ in some strongly limited parts may be explained as the result of an 
| incomplete inter-Gondwana erosion. 
The „intermontane sandstone zone“. 
A great variety of the continental strata is exposed in a long, 
strongly dislocated zone, running NNE—SSW through the whole 
country, and called here „the intermontane zone“, because it lies 
for a considerable part of its length between high mountain blocks 
and is intensely pressed together between them (see the geological 
map). The northern and southern extreme ends of the zone are 
somewhat difficult to fix. It may, however, be stated, that the zone 
to the southwest passes into the Precordilleran tertiary structure map- 
ped by Rassmuss, while to the north, according to the map of 
Brackebusch (1891) and W. Penck (1920), the same zone seems 
to continue in the mountains of the province of Catamarca, follo- 
wing the Valle Hermoso. This zone is a very remarkable tectonical 
feature of the region. It represents, as shown later on, a subandean, 
tertiary, tectonical phenomenon, not found in the area of the true 
pampean sierras. In the present chapter, however, may be described 
only the lithological characters and the stratigraphical relations of 
the rocks. 
The basal layers of this zone are visible only in two localities: 
1) in Carrizal, situated between the Cerros de San Antonio and the 
Cerro Villa Union, and 2) at the Puesto Altillo NW from Maz. At 
Carrizal the relations are as follows: over an opturned mica schist 
complex with limestone layers lies a greenish conglomerate, com- 
posed of well rounded pebbles with soft green-coloured cement 
