132 | ; SIERRA DE UMANGO 
The strata of the quaternary and recent accumulations in the j 
valleys being much softer are sometimes dissected into „bad land"- 
like forms, but generally they are not affected by erosion. 
At last may be communicated a scheme of the principal sculpture- 
zones as they depend on level and nature of the mother-rock. 
Flat topped summits and undulating upland surfaces. 
i Jagged (,cuchilla*) sculpture, draining to the 
Old crystalline quebradas. 
rocks. 
High destructive terraces. 
Continental i sandstones cones or sculpture with 
i bluffs and rounded forms. 
Gorges. 
,Bad land" sculpture. 
River terraces, 
plains. 
Quaternary and recent accumulations. 
Continental sandstones. 
Soft accumulation masses. Alluvium. 
H) MINERAL OCCURRENCES. 
Selenide bearing veins. 
In comparison with the Nevado de Famatina and its famous rich- 
ness of metalliferous minerals, well known also in the Anglo-Ame- 
rican mining world, the neighbouring mountains to the west, the 
Sierra de Umango region, have but insignificant occurrences of 
exploitable minerals to offer. The most worked ones are the silver- 
selenide bearing veins in the Cerro Cacho complex. The first dis- 
covery of these was made by the mining engineer E. Htinicken, 
engaged in the Famatina Copper Company. Later on professor L. : 
Brackebusch collected several specimens of these selenides du- 
ting his expeditions in the years 1875--1888. The specimens of 
Brackebusch were then more closely examined in Germany.! 
1 Otto: Eukairit aus Argentinien. Berichte der deutschen Chemischen Gesell- 
schaft. Jahrgang XXIII. 1890. 
F. Klockmann: Ueber einige seltene argentinische Mineralien. Zeitschr. für 
Krystallographie. Band XIX. 'N:o 3. Leipzig 1891. 
