SOUTH AMERICAN GEOLOGY 
203 
folding after the deposition of the Carbonic marine sediments. 
The whole continent was high during the Permian times, but I 
can see no evidence of any Andean mountain ranges at that time. 
With the beginning of Jurassic times we have a reappearance 
and extension of the Andean geosyncline, but the older geosyn¬ 
cline lay mostly east of this Mesozoic geosyncline and did not ex¬ 
tend so far either northward or southward. Moreover its rocks 
were intensely folded before the IMesozoic transgression and 
doubtless stood at some elevation during the Permo-Triassic up¬ 
lift, but, as I have just stated, there is no evidence that they 
formed a high mountain chain. 
Jurassic faunas are known from Colombia to Argentina and 
Chile, but they are so largely obscured by volcanic materials that 
the outcrops of the rocks carrying them are patchy, of limited 
extent, and of unknown relationships. The strata are confined 
tc- the Western Andean region so far as known, and although the 
details are not clear they appear to represent all of the major 
stages of Jurassic chronology. For example, Lisson recognizes 
the following stages in Peru: Hettangian, Sinemurian, Pliens- 
bachian, Bajocian, Bathonian, Callovian, and Portlandian. Some 
of these determinations are probably over sanguine, but we must 
remember that detailed areal, or stratigraphic, work in the sense 
in which we ordinarily use these terms, is practically unknown 
throughout the whole extent of the Andes. 
The generally accepted interpretation of the Andean geosyn¬ 
cline is that it separated the Brazilian, or better, the eastern South 
American massifs, from a Pacific massif, of which the crystalline 
schists of the Coast ranges represent the eastern edge. Very con¬ 
siderable faunas of old-world Mediterranean affinities have been 
collected from the South American Jurassic beds, and there is 
a considerable Late Jurassic flora known from northern Graham 
Land, which latter fact suggests a land-connection with Antarc¬ 
tica at that time along the Pacific side of the geosyncline. Doug¬ 
las ® predicates a post-Jurassic uplift with the formation of gran¬ 
itic batholiths. This may be true of local areas, but it certainly 
was not general nor synchronous for the whole region. I find no 
evidence of a break in Peru, nor is such a break clear in the 
southern Andes. There was doubtless a shifting in the geographic 
5 Quart. Jour. Geol. Soc. London, Vol. CXXVI, No. 301, 1920. 
