THE REGION ABOUT GOLDEN. 



99 



westward. This had undoubtedly been in action with probably but little 

 interruption from earliest time. The other components, secondary to that 

 just noted-and acting in directions more <>r less normal to it, B (fig. I ), were 

 evidently periodical in character. They reasserted themselves with special 

 intensity at the close of the Niobrara, effecting almost entirely at this time 

 the pronounced elevation under discussion, c (fig. t), the cross-section <>t' 

 which is that in Profile IV, PI. X. The Montana, Laramie, Arapahoe, and 

 early Denver beds were then deposited upon this fold, closing tin- first four 

 periods of history discussed above. 



The Profiles I-IV, PI. X, inclusive, may he regarded as transverse 

 (north-and-south) sections of this secondary fold in the several stages of' 

 its development according to the geological time represented by each. 

 Fig. 4 is more particularly a diagrammatic representation of the condition 

 of affairs at the close of the Laramie or at a point in time somewhere 

 between this and a stage early in the deposition of the Denver formation. 



Fio. 5.— Illuatrat 



By the post-Laramie movement the strata were bent up against the 

 range nearly at right angles and afterwards truncated by erosion. This 

 effect is produced in fig. 5 by supposing a slice of the block represented to 

 have been turned down through an angle of !•<) , as if hinged along the 

 line C D. The lunged portion is thus a diagrammatic representation of 

 the superficial outlines, as shown in detail by the map. 



The readjustment of forces by which the structure of post-Niobrara and Laramie times was changed to 



that of the present day. — At the close of the events coiisti tuting the fourth period 

 there began a readjustment of the major forces acting against the range, by 

 which the fold of pre-Montana age and its cap of horizontal strata gradually 

 gave way to the structure of later times. The results of this readjustment 



