28 GEOLOGY. 
the southeastern extensions of the mountain ranges which cross the Colorado, and perhaps in 
the continuation of Monument range itself. From the relation which these mountain chains bear 
to the great table-land lying east of them, of which the western portion consists mainly of 
Carboniferous limestones, there is little doubt that the limestones which they contain are of 
Carboniferous age. 
The view represented by the following cut, taken from a point above the mouth of Bill 
Williams’s Fork, is one of peculiar geological interest, as illustrating the dependence of scenic 
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Fig. 6.—vIEW OF NORTHERN ENTRANCE TO MONUMENT CANON. 
character upon geological structure. On the left it is bounded by hills of soft Tertiary 
conglomerate, covered with quaternary grayel, of which the yielding materials, fashioned by 
atmospheric erosion, have assumed the form of low, broad-based cones, whose outlines present 
& series of graceful curves. In front rises a table-topped mountain, of which all the upper 
portion is trap, with its characteristic mural faces. On the right masses of granite descend to 
the water’s edge, exhibiting the rugged and irregularly rounded outlines which this rock is so 
prone to assume. “ie 
