14 SIERRA DE UMANGO 
limestone to quite an insignificant extent, except in some parts of 7 
the Sierra de Cördoba and in the Sierra de la Huerta. 
Among the other sedimentary members in the Umango pregra- 
nitic series the micaschists occupy different, broad zones, the most i 
important of them being a more central one. The quartzitic schists 
are always intercalated in these rocks, partly in regular alternation, 
partly in mightier zones. 
Fig. 3. Contorted and thickened layers of silicious limestone (white) in micaschist 
(grey). NW from Carrizal. Height of the rock-wall about 50 m. 
Apart from these principal types to a smaller extent we find 
interstratified members of strongly pressed, dark schists. These 
may be considered partly of sedimentary, partly of pyroclastic ori- 
gin. 
All these layers form a concordant prism without any sign of 
break in the sedimentation. Conglomeratic layers are completely 
lacking. 
Below follows a closer lithological characteristic of the named 
sedimentary types. | 
1 A. Stelzner: Mineralogische Beobachtungen im Gebiete der Argentinischen 
Republik. Tscherm. Min. und Petrograph. Mittheilungen. IV. 1873. Pag. 230, 
and foll. 
en NT u en ee She de ne "re ee ee es re 
PE ee SS 
Ada FaR RR 
SIN 
a De ara er en 
