^,,,^1 GEOLOGY SECTION NO. 6. 209 



PEALE.J 



The lower part of tlie bluff is covered with debris, but as seen from 

 the other sections made near this locality, is i^robably composed of the 

 Potsdam sandstone. Bed No. 1 contains Orthis, BatJiyurus Saffordi, (Bil- 

 lings,) and Lmguhpis or Lingula. Whether the yellow limestone, bed 

 6, belongs to the Silurian or to the Carboniferous is uncertain. Careful 

 search revealed no fossils. I think it probable that it is the equivalent 

 of the Niagara limestone. The angle of inclination of these beds is 15°. 

 Just above we have beds of massive white limestone. Goiug westward 

 we pass over a rolling country which, as a few outcrops indicate, is un- 

 derlaid by soft red and gray sandstones, the latter being above the red- 

 beds, and' dipping at an angle of from 10° to 12°. We then begin to 

 ascend the hills, and find them so covered with debris that very little 

 can be seen. 1 think, however, that the illustration, Fig. 1, Plate V, 

 presents the correct view of the beds. The ridge above West Creek is 

 granitic, giving a red debris. The elevation of the ridge is about 7,556 

 feet. 



Eeturning to the east side of Trout Creek and following one of the 

 little streams toward its source, we find that only the Silurian layers are 

 to be seen resting on the granite. Section No. 7 is made at the point 

 B in Figs. 1 and 3, Plate Y. 



Section No. 7. 



Thickness 

 in feet. 



1. Granitic. 



2. White and yellowish sandstone 43 ") 



3. Pink sandstone 16 l^^f^ 



4. Dark purplish-brown' sandstone 5 | 



5. Green sandstone 3 j 



6. Brick-red shaly limestone 19 



7. Pale-pink and gray limestones - 16 



8. Pink limestones. 



About 6 feet below the top of bed No. 3 is a layer of pink quartzite 

 which, at the point where the section was made, was only 2 feet in width. 

 On following the bed northward, however, it increases to 4 or 5 feet. 

 At the top of No. 3 is a shaly layer 2 feet thick, in red and pink bands. 

 Nos. 4 and 5 are alike except in color. They are very coarse-grained 

 and soft. The red limestones (No. 6) are full of green spots, probably 

 glauconite. In the limestones the same fossils occur that we found on 

 Trout Creek. They cap the hill. Between B and C in the figures on 

 Plate y huge granite boulders are strewn over the surface. The granite 

 is soft, and readily disintegrates. The feldspar is red orthoclase and the 

 mica black. Masses in some places have weathered into forms resem- 

 bling those found in Monument Park. At the point C we have only 

 the lower sandstone, beds 2 and 3, and those here seem to be much 

 changed. Standing on this hill we see all about us similar monuments 

 capped with fragments of beds. We can also see Platte Mountain, to 

 which we have alluded before. There seems to be a line of these jagged 

 granitic points, the course of which is northwest and southeast, Platte 

 Mountain and the Palisades, near the Platte Eiver, being the most prom- 

 inent. South of Platte Mountain these detached points show merely the 

 general course. A comparison of the sections given above shows that 

 the Potsdam group is represented by sandstones having a thickness of 

 from 60 to 80 feet, while the beds that represent the Quebec group are 

 a little over 100 feet thick. Comparing with the section (No. 3) made 

 at Glen Eyrie, we see that the beds on the west side of the range are 

 14 G s 



