70 PRESIDENT’S ADDRESS—SECTION CO. 
shows a series of successive plicated bands with more or less 
parallel trends. In eastern North America the Pre-Ordovician 
folding of the Adironacks in New York was followed at the close 
of the Ordovician by that of the Green Mountains in Vermont ; 
and the Blue Mountains are older than the Alleghanies. In 
western North America the Wahsatch Mountains, which are 
contemporaneous with the Alleghanies, preceded the Sierra 
Nevada, and these preceded the Californian coast ranges and 
the Rocky Mountains. In Asia the Kuenlun Range, on the 
northern side of the Thibetan plateau, preceded the Himalaya, 
and these the sub-Himalaya. In South America, the mountains 
of Brazil and Bolivia preceded the Andes. Even in Europe, 
complicated though its structure be, the folded bands get younger 
towards the south. Thus the region from central Britain in a 
south-easterly direction to central Germany was folded between 
the Silurian and Devonian; that from south Britain east 
through northern France and Westphalia to south Russia, 
between the Carboniferous and the Trias; central France and 
central Germany between the Triassic and the Jurassic ; south 
Germany between Jurassic and Cretaceous ; and Switzerland in 
the Tertiary. 
Since the commencement of the Palxozoie era few regions 
are known to have been plicated more than once ; but central 
Germany has been folded at least twice, although along different 
lines ; and according to Professor Green, there were in South 
Africa two periods of plication between the Devonian and Trias, 
and each took the line of the Zwartebergen ; but since the Trias 
this region has been undisturbed. Even in those regions, like 
the Alps and Himalaya, which were plicated in the Tertiary era, 
there appears to have been no previous plication of the district. 
This opinion is opposed to statements usually found in text-books ; 
but the difference is due to distinguishing simple regional uplifts 
from those which were accompanied by plication. Regional 
uplifts and subsequent depression have often preceded the 
formation of a mountain range; but the true mountain uplift, 
which is accompanied by the irruption of granite and the 
contortion of the rocks, is seldom, if ever, repeated. The moun- 
tain uplift, however, may not be simple; it may consist of two 
or more periods of folding following closely after one another. 
A few examples showing the differences as well as the resem- 
blances between these kinds of uplifts are necessary to establish 
my position. 
In the Pyrenean Region disturbances, of which I cannot find 
a sufficiently full account, took place between the Devonian and 
Carboniferous periods, and were followed by subsidence and 
sedimentation up to the middle of the Cretaceous, when a gentle 
uplift took place without contortion. This was followed by a 
second subsidence and sedimentation to the close of the Eocene. 
