SOUTH AMERICAN GEOLOGY 
191 
I have already enumerated the two principal areas of supposed 
pre-Cambrian, that of the Northern and the Eastern highlands, the 
latter constituting what Branner called the Brazilian complex. 
There are smaller areas of similar rocks in southern Colombia, 
in the state of Matto Grosso, Brazil, in the provinces of Buenos 
Aires, Cordoba and Santa Cruz in the Argentine, and along the 
West Coast at various points in Peru and from about Latitude 23° 
in Chile southward to Cape Horn. This zone of crystalline schists 
along the West Coast has been interpreted as representing an old 
land-mass that formed the eastern boundary of the Andean 
geosyncline, and which is now submerged beneath the Pacific 
Ocean except for its eastern margin. These schists, at one point, 
along the Rio Bio Bio, in southern Chile, contain recognizable 
Mesozoic plants which throw some doubt on the foregoing inter¬ 
pretation, but the latter may simply represent an infolded remnant 
of much less metamorphosed Mesozoic rocks which overlapped 
the eastern margin of the old land-mass and which was caught in 
the folding that occurred toward the end of the Cretacic times. 
There is considerable evidence of a Pacific land-mass, especially 
in the later history of the continent, and, obviously, there was a 
western shore to the Andean geosyncline throughout its history but 
absolutely nothing is known of its probable extent, except that 
during the Miocene it appears to have been of sufficient size to 
prevent free intercommunication between northern Peru and south¬ 
ern Chile. 
I have outlined these various areas of supposed old rocks on 
the map showing the outcrops of the early Palezoic areas (plate 
vii), and as will be observed there is certainly a suggestion of a 
continuous crystalline mass extending beneath northern Argentina 
and all of Brazil south of the Amazon River. I think that we 
know enough about the geology of South America to warrant the 
statement that the early Paleozoic sediments are very poorly rep¬ 
resented, and to attribute this more largely to lack of deposition 
rather than to subsequent erosion or burial. No rocks of Early or 
Mid Cambric age are known and it is concluded that the continent 
was above the sea during that time. Aside from some unfossili- 
ferous metamorphics of supposed early Paleozoic age in Brazil, 
there is a small area of Late Cambric rocks in northern Argentina 
and in southern Bolivia, where a few brachiopods and trilobites 
