NOTES ON THE GEOLOOY OF SOME LOCALITES 

 NEAR CANON CITY, FREMONT CO., COL. 



B\' S. G. Williams. 



Dr. F. V. Hayden, United ^States Geologist : 



Dear Sir: I take i)leasnre in fonTarding to you, accordiug to your 

 request, some sections, with brief notes tbereou, made by me duriug the 

 summer of 1S74, in the course of some explorations of coal and oil lands 

 in Fremont County, Colorado. 

 Yours, respectfully, 



S. G. WILLIAMS. 

 CiiEYELAND, Mcirch 31, 1875. 



The oil-springs mentioned in your report for 1869 are in the caiion of 

 Oil Creek, a northern tributary of the Arkansas, which flows down from 

 the flank of Pike's Peak, between the main range and a lofty spur that 

 is sent off to the southeast, and dies out in the plains a little north of 

 the Arkansas. Thus the rocks from which the oil-springs issue are, as 

 you have suggested, in a synclinal trough, of which the axis is near the 

 main range, while the canon of Oil Creek is cut through near the foot of 

 the spur. I sent a trusty person on horseback up through the park 

 which lies at the head of the caiion, and, from his observations and my 

 own, I can give the following section, which extends from the head of 

 Oil Creek Park to the Arkansas Eiver, about fifteen miles from north to 

 south. 



Descending section. 



Feet. 



8. Alluvium, underlaid by Cretaceous shales, Arkansas Yalley 



7. Black shale, with layer of sepdaria, and BacuUtes 50 



6. Limestone of drab color 15 



5. Thick-bedded ferruginous sandstone 40 



4. Eed and yellow sandstones, often thick-bedded, with occasional 



layers of bluish shale 1, 000 



3. Bright-red sandstones 100 



2. Mottled marble 15 



1. Whitish limestone, weathering rough, and full of caverns 5 bot- 

 tom not seen ; visible 50 



These thicknesses are all estimated, except Nos. 1, 2, and 3. Dip a 

 little west of south 15°. Nos. 1 and 2 are probably Carboniferous ; rocks 

 holding the same relative position in the Arkansas Caiion, and from 

 which I have fossils, are certainly of that age. ISTo. 3 is probably Triassic. 

 !No. 4 may be Jurassic, in whole or in part. I forward you the only fossil 

 I found in this series of strata, a Gasteropod, found a little more than 

 200 feet above the base of No. 4, at the horizon of the oil-springs. Nos. 



5, 6, 7, and 8 are undoubtedly Cretaceous. Kos. 5 and 6 form a steep 

 ridge, capped by No. 6 a little south of the mouth of the canon. No. 7 

 forms a second ridge still farther south, the summit of which is preserved 



No. 5 2 



