258 GEOLOGICAL SURVEY OF THE TERRITORIES. 



Above Gothic Mountaii], at the head of East River and on the same 

 side of the stream, is Slate Mountain, which is so called from the fact that 

 it is largely composed of bluish and black slates, all of which belong to 

 the Cretaceous formations. At the base of the mountain the quartzite 

 of IS'o. 1 outcrops. These shales prevail toward the southwest beyond 

 Slate River. Bellevue Mountain, opposite Slate Mountain, at the head 

 of East River, is similar in its composition. 



From East River we crossed to the head of Rock Creek, which is one 

 of the branches of Roaring Fork, wliicb it joins below Sopris Peak. 



On Rock Creek, as i have already intimated, and as is shown in Fig. 

 3, Plate XVIII, the beds are again inverted on the east side. The in- 

 vestigation of the beds on the west side of the creek had to be left to 

 the explorations of the next season. " 



The following section was made a few miles down the creek on the 

 east side, and is in ascending order : 



/ , Section No. 27. 



1. Reaching from the bed of tli.e creek up on the hill to the point a 

 in Fig. 2, Plate XVIII, we have a space filled in with limestones 

 and black shales. 

 a, 2. Very hard calcareous black shales, breaking into laminae of about 



of an inch, 44 feet 7 inches. 



3. Argillaceous sandstone, in places very shaly, 89 feet 2 inches. 



4. WMte limestone, breaking into laminae of about ^ of an inch thick- 



ness, 6 feet. 



5. Black argillaceous shales, with interlaminated bands of hard sand- 



stone, 191 feet 3 inches. 



6. Space of which the upper part is probably filled with white sand- 



stone, and the lower part witti alternate sandstones and black 

 shales, 213 feet. 



7. Bluish shaly sandstone, weathering a rusty color, 8 feet. jl 



8. Rusty-colored calcareous sandstone, 15 feet 10 inches. 



9. Bluish calcareous sandstone, 4 feet. 



J). 10. Yellowish-white sandstone, containing impressions of leaves, 82 

 feet 8 inches. 



11. Shaly sandstones, with included hard bands. The lower beds 



are rusty-colored and the upper ones greenish ; 45 feet 4 incbes. 



12. Space, the bottom of which is probably filled with shales, gradu- 



ally giving place to limestone. At the top there is an outcrop 

 of blue limestone, having near the upper part a band of green- 

 ish shale ; 90 feet 3 inches. 



13. Yellowish sandstone, with bands of light blue limestone, 36 feet 



3 inches. 



14. Space, in which, as indicated, there are coarse red and gray lam- 



inated sandstones, 83 feet 10 inches. 



15. Coarse purplish conglomeritic sandstone, 12 feet. ; 



16. Rather fine variegated sandstone. 



17. Purplish conglomerate. 



c. 18. Space filled with alternations of conglomerates and fine shaly 

 sandstones. The general color is a reddish-streaked and mot- 

 tled with gray. On top there are some white beds, which, from 

 a distance, I took to be limestones. 

 I was unable to determine the exact thickness of the last beds in the 

 section. Above them, there is but little doubt that all the beds reach- 

 ing through the Carboniferous to the base of the Silurian are present. 



