68 Scientific Intelligence, 
Eocene. The greater part of the denudation is assigned to the 
Miocene, because the conditions appear to been more favor- 
able to a rapid rate of destruction in that age than subsequently. 
The climate appears to have been humid, while the elevation was 
e time gradually increasing, both conditions being 
i atio moval of the rocks. The 
cated by many evidences. They consist of remnants of a former 
topography, preserved in a few localities from the general wreck 
of the land, and which show the same general facies of cliffs and 
cafions as those of more recent formation. And as the more 
recent sculpture owes its peculiarities in great part to the aridity, 
so, we conclude, must these more anci i 
little change for an immense period of time. 
“And now the relation of the High Plateaus to the Plateau 
Province at large becomes evident. Th 
great masse i 
trict of High Plateaus. From the region east of the High Pla- 
teaus also very large areas of it have been removed. The Upper 
