DETRITIC FORMATIONS 13 
pearance as that farther to the southwest. Regarding the tectonics 
may be mentioned, that the yellowish sandstone upward changes 
its dip forming a flat-lying cover over the crystalline bulk. It is 
the only part of the area, where the Gondwana have been observed 
in an almost horisontal position resting zpon the basement’s upland 
surface. 
_ Northward off this locality the Gondwana layers rapidly dissappear 
due to faults. 
Fig. 8. A cut through the sediment mantle along the southeastern slope of the 
Cerro Villa Union in the Quebrada de los Lagares. Lower Gondwana sandstone 
and slate in regular alternation lying over the crystalline basement (mica schist). 
Looking south with the Cerro Bola in the distance. 
. The region of the Cerro Punta Colorada — Las Ramaditas. 
A continuation of the southeastern flanc-cover to the northeast 
forms in some degree the group of foothills, situated between the 
steep eastern side of the Cerro Villa Union and the valley of Vin- 
china. Here tlıe cover, however, has been broken into many small 
blocks and the outcrops of the strata show therefore a greater 
variety. Also the dips are more variable. This foothill-group 
consists of two essential parts, an exterior one, facing the eastern 
lowland, the Cerro Punta Colorada and its ramifications consisting 
of sandstones, and an interior one, Las Ramaditas, composed of 
