316 GEOLOGICAL SURVEY OF THE TERRITORIES. 



at a depth of about 240 feet. No careful record was kept of the six-ata 

 through which the drill passed, but it struck a "rotten red sandstone" 

 above the conglomerate. That the hard bowlders contained in the 

 conglomerate would be very injurious to the chisel can readily be im- 

 agined. In order to carry on boring-operations, a derrick of 64 feet in 

 height was erected, and the chisel and drill used weighed, together 

 with socket, &c., 2,500 pounds. At present the works are not in opera- 

 tion, owing to a temporary absence of the operators. 



Judging from evidence obtained in Doctor Peale's district, as well as 

 from a point in section &, it seems altogether probable that older forma- 

 tions underlie, frequently conformably, those we find upon the surface. 

 As far as determinable, no red conglomerate crops out in Oil Greek 

 Valley, although the evidence of its existence there, at a depth of 240 

 feet, is afforded by the results obtained, and this existence may furnish 

 hints for inferences to be drawn at other localities, where similar circum- 

 stances occur. A section through Oil Creek Valley, running nearly 

 north to south, (Plate XI,) will show the relations of the strata. Anal- 

 ogous to the Mesozoic sections previously given, the red shaly sandstone 

 (c) is overlaid by whitish and greenish shales, (e/,) separated from those 

 superincumbent by a thin stratum of brownish sandstone. Above this 

 sandstone remains of saurians were found, fragments of bones, but too 

 poorly i^reserved to admit of any identification. Whether they are in 

 situ or not at that point I am unable to say. Overlying the Meso- 

 zoic, we lind in this valley the Cretaceous, beginning, as usual, with a 

 yellow to light brown sandstone. A number of box-shaped bluffs are 

 formed by the upper shales and capped by this sandstone. Taking a 

 section through one of them, situated a short distance north of station 

 88j we find the following succession, (Pig. 1, Plate XII :) 



CL 60 feet red sandstone. 



J). 40 feet white and greenish shales. 



c. 8 feet brownish sandstone. 



d. 35 feet white and yellow shales and marls. 



e. 10 feet light-brown sandstone. 

 /. 25 feet white sandstone. 



g. 40 feet light-brown and yellow sandstone, interstratified with dark- 

 gray slaty shales. 



Only a very small area is covered by the Mesozoic formation in section a, 

 as it is exposed mainly along the eastern edge of the Front range, merely 

 in a narrow, sometimes broken, line. With the exception of those occur- 

 rences along Oil Creek, in the mouth of the Cretaceous bay, west of Can- 

 yon, and at a point north of station 95, the remnant of some small bay, 

 section a shows no strata removed from mountain-slope that might be 

 referred to this group. Careful investigation, perhaps the discovery of 

 some fossils in these beds, may lead to a recognition of their proper 

 position in the adopted scale of geological ages; and until that is accom- 

 plished, it will be necessary to speak with reserve when parallelizing 

 these formations with Triassic and Jurassic of other regions. 



Continuing in a conformable series, we find the formation referred to 

 the Triassic and Jurassic overlaid by the Cretaceous. The charaqter of 

 the Cretaceous formation in the western Territories has been so well 

 established that it is comparatively easy to identify its various members 

 and refer them to an adopted schedule. As seeninthe sections of Plate — , 

 a very distinct horizon is formed by a stratum of yellow or brownish 

 sandstone, quartzitic at times, usually capping a row of bluffs. This 

 sandstone contains numerous remains of plants in different stages of pres- 



