ANTECEDENT AND CONSEQUENT VALLEYS. 163' 
moisture, and a greater quantity of rain falls on them, or in their vicinity. 
The region of country adjacent to the mountains receives a portion of this 
extra rain-fall, so that this dynamic agency increases from the plains to the 
summits of the mountains, probably in some direct ratio. This increase of 
the eroding agency, and the greater exposure of the soft beds, probably 
accounts for the fact that the lowest country is at the foot of the mountains. 
There is a limit to the effect of these conditions, for it should be 
observed no valley can be eroded below the level of the principal stream, 
which carries away the products of its surface degradation; and where the 
floor of such a valley has been cut down nearly to the level of such a 
stream, it receives the debris of the adjacent cliffs and mountains, and in this 
way the rocks composing the floor are usually masked, to a greater or lesser 
extent. The same topographic facts, under like conditions, are found on 
the eastern slope of the Rocky Mountains, in Colorado Territory, and the 
valleys which run into the South Platte from the south, between the hog 
backs, are lower than the mesas and plateaus farther away from the mount 
ains, but not lower than the flood plain of the river. 
I have endeavored above to explain the relation of the valleys of the 
Uinta Mountains to the stratigraphy, or structural geology, of the region, 
and, further, to state the conclusion reached, that the drainage was estab 
lished antecedent to the corrugation or displacement of the beds by faulting 
and folding. I propose to call such valleys, including the orders and vari 
eties before mentioned, antecedent valleys. 
In other parts of the mountain region of the west, valleys are found 
having directions dependent on corrugation. I propose to call these conse 
quent valleys. Such valleys have been observed only in limited areas, and 
have not been thoroughly studied, and I omit further discussion of them. 
In the great metamorphic belt extending through the Territory of Col 
orado, comprising the Rocky Mountain chain of this Territory, the structural 
geology is exceedingly complex, while the drainage is comparatively simple, 
and only to a limited extent does it seem to be governed by geological 
structure. The conclusions to which I arrived were that the present drain 
age was established in rocks now earned away from the higher regions, but 
still seen to be turned up against the flanks of most of the ranges. 
