ORIGIN OF THE ANDES 
15 
RECENCY OF ORIGIN OF THE ANDES 
By Edward W. Berry 
v 
Geologists in general, and particularly the authors of textbooks 
and speculators on geophysics, assume that periods of earth’s 
crustal folding in the past were contemporaneous with periods of 
mountain-making and were both but different expressions of the 
same forces.^ I am not aware that there is any direct evidence 
for this assumption, and although I am not proposing to discuss 
this problem in the present brief outline, I wish to call attention to 
this feature in connection with the following notes on the age of 
the Andes. 
The subject may be introduced by a brief statement of what 
is embraced under the term Andes, emphasizing how slight is 
our detailed knowledge of the age of the rocks in the various 
ranges; after which effort will be made to piece together the 
scattered bits of evidence relating to folding and uplift. 
The Andes comprise a rather complex upland of ridges and 
plateaus extending from the Caribbean Sea to Cape Horn, or 
through some 65 degrees of latitude. As a major feature of 
the earth’s crust their extent is much greater than this, since the 
tectonic zone of which the Cordillera is the above-sea expression, 
can probably be closely connected with the Antillean arc on the 
north, and with the corresponding arc to the southward which 
connects with Graham Land and runs for an unknown distance 
across the face of the Antarctic continent. No other mountain 
system is so continuously lofty, so constantly overhangs a coast, 
or drops immediately to such profound oceanic depths. The 
gradient of the south slopes of the Himalayas is similar, but there 
the lower slopes are covered with the deposits of the Gangetic 
plain instead of by the waters of the largest ocean. Several 
1 This subject is discussed in some detail by Prof. H. F. Reid, in a paper read 
before the Geological Society of America, in December, 1920, in which he especially 
emphasizes the distinction between these two groups of forces. 
