72 SIERRA DE UMANGO 
almost the same inclination, and direction along the whole southeas- 1 
tern side of the Cerro Villa Union. 
Looking from the Pagancillo lowland toward the mountain, the - 
steeply dipping cover appears as a gigantic „steel sheet“ capping — 
the crystalline mass. A study of the succession of the strata in this 
cover appearing in profiles in the many crosscutting quebradas 
reveals, that several members from the Guandacol profile are lacking. 
A good cut through the cover can be studied in the Quebrada de Los 
Lagares (fig. 8) situated to the northwest of the little ranch Aguada 
de los Burros (this locality lies on the path from Villa Union to 
Guandacol). Over the crystalline basement, here composed of a 
mica schist, lies with a dip of almost 45° a pale yellowish sand- 
stone, carrying a clayish slate in regular alternation. The basal 
conglomerate and the „graywacke“ lacks here. The yellowish sand- 
stone is succeeded by a red one of the same dip. The yellowish 
sandstone incl. the slaty interstratifications attains surely the thick- 
ness of two hundred meters. The red beds above contain some 
concordant sills of melaphyre, partly of spilitic development. A lon- 
gitudinal erosion valley separates the red layers from the immediate 
horst-flanc cover, the former standing out as long-crested foothills 
(visible on the map). The dark melaphyre sheets are discernible 
already at a long distance. 
The thick, chocolate-brown tuff sheet from the Guandacol profile 
is not represented here. But the melaphyre corresponds surely to 
the same volcanic phase. 
Further to the northeast one finds the same succession of strata 
as in the Quebrada de Los Lagares. In the vicinity of the mouth 
of the Quebrada Barreal (not named on the map), situated opposite 
the Cerro Punta Colorada, at the base there appears the same yel- 
lowish sandstone resting directly on the basement, here composed 
of granite and oi intruded and banded schists. The slaty inter- 
stratifications seem to be lacking. Over the yellowish lower 
Gondwana sandstone lies then a red sandstone of the same ap- 
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