2 GEOLOGY OF THE DENVEE BASEST. 



may therefore appropriately treat first of the general characteristics <>t' 

 the whole belt, and then of the details peculiar to the special area under 

 consideration. 



The whole region is remarkable for the intimate dependence of topo- 

 graphical form upon geological structure. To such an extent is every 

 detail of topography founded on some underlying geological cause that 

 the field geologist saves much unnecessary labor by drawing his general 

 deductions from the larger and more characteristic features, and by looking 

 for variations from the general rules of geological structure thus deter- 

 mined only where some peculiar variation from the characteristic type is 

 found in the topographical form. 



The region described comprises three distinct types of topographical 

 structure: (1) mountain slopes; (2) foothills proper; (3) plains. 



MOUNTAIN TOPOGRAPHY. 



The mountain topography is necessarily much older than that ol the 

 foothills or the plains, since not only the sediments of which the latter are 

 composed, but also the waters which have carved them into their present 

 form, have been derived from the mountain region. It is therefore neces- 

 sary to consider briefly the topographical structure of the entire mountain 

 area in so far as it has had any influence upon that of the foothills or the 

 plains. 



The eastern front of the Colorado Range has a general north-and-south 

 trend; that is. this is the general direction of its prominent mountain laces. 

 What inighl be called its shore-line, however, or the line which marks the 

 junction of the sedimentary beds deposited along its thinks with the com- 

 plex of crystalline rocks thai constitute the mountain mass, is far from 

 straight in detail. 'The striking feature of its divergence is the tendency to 

 form loops or bays opening out to the southeast. The most prominent of 

 these loops or bays are that to the south of Tikes Peak in which Canyon 

 City is situated and thai called Huerfano Park, still farther south, between 

 the Greenhorn or Wet Mountains and the Sangre de Cristo Range. One 

 less prominent in the present topography is that at Mauitou, north of Pikes 



P.ak. The shore-line iil the Denver Basin area forms part of a shallower 



