SOUTH AMERICAN GEOLOGY 
187 
OUTLINES OF SOUTH AMERICAN GEOLOGY^ 
By Prof. Edward W. Bfrry 
Johns Hopkins University 
There are two factors that render uncertain any attempts to 
present the geological history of South America at the present 
time. In the first place its area of nearly seven millions of square 
miles, or twice that of Europe, receives less detailed study than 
any other continent; accurate maps do not exist; and vast areas, 
such as the Amazon Basin, the Guiana and the Andean Highlands, 
and the Grand Chaco, are among the most difficult and inaccessa- 
ble regions on the face of the globe. The second factor is, that the 
earlier physical history has been greatly obscured if not entirely 
obliterated by the events of its later history, largely that of Tertic 
times. We shall probably never know just what erosion accom¬ 
plished when the continent stood high during Permian times, or 
what underlies the great segment east of the Andes, unless per¬ 
chance drilling on a super-grand scale for oil will eventually be 
undertaken, and even then we shall perhaps be no better off unless 
the human nature of oil companies and oil geologists changes 
marvelously. 
In its present broader features South America has been likened 
to North America — the roughly triangular form, the western 
Cordillera, the northern highlands, the eastern highlands, the cen¬ 
tral plain — the Amazon system corresponding to the St. Law¬ 
rence, and the La Plata system to that of the Mississippi. Such 
comparisons are most superficial, however, and the geological his¬ 
tory of the two continents is necessarily quite different. No con¬ 
tinent possesses the anomalous climatic and topographic features 
of present-day South America. There you may stand on glaciers 
and see sugar cane beneath you, or freeze in a mine-camp above 
1 Paper read before the New York Academy of Sciences, October 2, 1922. 
