PEALE.] 



GEOLOGY PIKEti PEAK. 205 



difference in dip between the Silurian and the Triassic in section Ko. 4, 

 also points to an elevation rather than depression. Near Pike's Peak 

 the force was direct enough to elevate the Silurian layers above the sea, 

 and cause them to- form part of the shore-line, while the border of the 

 sea retreated to the eastward. To the north and northeast, however, 

 the force was more widely distributed, the elevation more general, and 

 we have the margin of the sea more to the westward. The widening of 

 the sea-borders would, of course, result in a shallower sea, and the char- 

 acter of the red sandstones points to a comparatively shallow sea during 

 iheir formation, while their structure shows them to have been derived 

 in all probability from the red porphyritic granite found along the 

 margin of the foot-hills from Denver southward. 



Pike's Peak is composed of a very fine-grained reddish granite. It is 

 a question whether the rock is eruptive or metamori)hic ; I incline, how- 

 ever, to the opinion that it is metamorphic. About the base of the peak 

 I found, rather abundantly, good crystals of amazon stone (green feld- 

 spar) and smoky quartz. 



It is doubtful whether the sedimentary beds ever extended across the 

 range of foot-hills from the east to the west side. There is no positive 

 evidence anywhere along the range that they did. 'No remnants are to 

 be found on the plateau, and -it is scarcely probable that the beds wou-ld 

 have continued uninterruptedly across without having left some trace. 

 The nearest approach is near the foot of Pike's Peak, where the older 

 formations extend for some distance up on the hills near the Ute Pass; 

 but this, as I have before said, is due to the existence here, during Silurian 

 times, of a bay extending to the westward. I do not think it reached 

 to the head of West Creek, although, as we will see further on, the Silu- 

 rian beds on Trout Creek are exactly like those in Glen Eyrie. Taking 

 a general view of the sedimentary formations along the eastern flank of 

 the mountains, we see that the red sandstones have their greatest devel- 

 opment near the exit of the South Platte from the mountains, and that 

 as we go southward they become much thinner. This is shown by the 

 sections in Plate IV. In No. 1, the section at the Platte, the red-beds 

 have an approximate thickness of 2,000 feet, which at Pleasant Park, 

 No. 2 in the plate, has decreased to 1,280 feet. At Camp Creek, sec- 

 tion No. 3 in the diagram, I was unable to ascertain the exact thickness, 

 as the line of junction between the red-beds and those next below was 

 very obscure. I have, however, estimated the thickness at 1,000 feet. 

 With the exception of No. 1 Cretaceous, the other beds also decrease to 

 the southward, as seen in the diagram. 



Considering the strike, we find that north of the divide, or Pinery as 

 it is sometimes called, it is very uniform. Thus, at the Platte, it is north 

 25° west ,• at Willow Creek, north 35° west ; and at Pleasant Park, 

 north 30° west. Below the divide is a turn to the westward, and east 

 of Glen Eyrie the strike is north and south. From this point, as we 

 have already seen, the strike changes. I have already treated of the 

 dips. 



The Garden of the Gods, the springs, and the various beautiful caiions 

 about the foot of Pike's Peak have been so fully described in previous 

 reports that I will but refer to them here. It is to their attraction, per- 

 haps, that Colorado Springs and the village of Manitou owe their pros- 

 perity. Within a year the former town has more than doubled, both in 

 size and population. At Manitou is a large hotel for the accommodation 

 of the visitors that every summer resort to the springs. There are also 

 many beautiful cottages about the springs, and the springs themselves 

 are inclosed in tasteful pavilions. 



