POST-CEETACEOUS DISTUEBANCES. 
215 
indication we now have raises a presumption in favor of this complete con- 
nection; but it is unnecessary to speculate when the facts can be learned 
by observation. 
North and south of this unexplored locality, where it is supposed that 
an arm of the Cretaceous sea reached out to join the Pacific, there lay land 
areas of considerable extent. The northern was the old mainland of the 
Great Basin; the southern was the Arizona land, of which such frequent 
mention has been made in this work. The northern area was much larger 
than the southern. It still remains possible that the two were one continu- 
ous area joined by an isthmus, or that the Arizona mass was a long Malacca- 
like peninsula projecting southeastward from the former. 
At the close of the Cretaceous important vertical movements were 
inaugurated, which finally revolutionized the physical condition of the 
region. Around the borders of the Plateau Province some important flex- 
ures were generated at this epoch, and portions were uplifted sufficiently to 
undergo a large amount of denudation. Perhaps the most striking instance 
of this is the one described in the work on the Hmli Plateaus extending 
from the eastern and southern flanks of the Aquarius southward to the 
Colorado. This area consists of Jura-Trias strata, from which the Creta- 
ceous had been eroded before the deposition of the Tertiary. Beneath the 
lava-cap of the Aquaritis the lower Eocene may be observed resting upon 
the Jurassic sarrdstone, and a little further westward it lies across the 
basset edges of the Cretaceous. Southeastward from the Aquarius and 
along the course of the Escalante River the same relation is inferred 
to have existed, but the great erosion has swept everything bare down to 
the Jura-Trias, and the evidence of the extension of the Eocene here is 
mainly indirect. But the two monoclines are in full view, between which the 
Escalante platform was hoisted, and their age is unquestionably pre-Tertiary 
and post-Cretaceous. These relations are repeated in man}^ other localities, 
and they indicate to us very decidedly that the Cretaceous closed amid im- 
portant disturbances. 
Still the deposition of strata was not yet ended. It went forward with 
seemingly undiminished rapidity, but under circumstances somewhat differ- 
ent from those hitherto prevailing. Soon after the advent of the Eocene 
