KNDLicH.] GEOLOGY SAN LUIS DISTKICT, SECTION A. 



QIK 



15 



Yellow shales and limestones. 



White and gray quartzitic sand- 

 stone. 



Yellow shales. 





"White shales and dolomites. 







"White sandstone. 



White shales and marls, dolomitic. 



Eed quartzitic sandstone. 











Grayish and greenish shales. 



Eed sandstones, partly shaly. 



Eed sandstone. 







"White sandstone. 



Eed and brown shales, sandy. 







Eed shales, sandy. 





Eed sandstone, shaly. 



Eed sandstone. 







Eed conglomerate. 



Eed conglomerate. 



Eed conglomerate. 



Eed sandstone. 



Eed sandstone. 



Eed sandstone. 







"White sandstone and shales. 



Bluish shales and limestones. 



VVihte sandstone. 



Eed shales. 





Eed sandstone. 



a 





Eed sandstone. 



Eed sandstone. 



Granite. 



Granite. 



Granite. 



Aronnd the eastern and northeastern base of station 11 the red beds 

 are found at almost every point varying to some extent in the angle of 

 their dip ; although, taken all in all, the disturbance i)roducing the 

 never-missing dip in the Mesozoic beds must have been quite a consid- 

 erable one ; but, strange as it may seem, it was certainly one that 

 extended over a large area of country, for I have not noticed a single 

 instance along about seventy miles of the eastern slope which came 

 under my observation in which these beds were 'not conformable with 

 those overlying them, and, as far as could be judged, also with those 

 underlying. Undoubtedly, the action producing this effect must Jiave 

 been of a very simple and uniform chiiracter, although probably con- 

 tinued for some considerable length of time. 



On the eastern border of Oil Creek Valley, the red beds are exposed 

 only at a few isolated points ; but along the western side, they form one 

 almost continuous line, and it is there that the general rising of the 

 heavier masses of land "west of it seems to have been stronger. In con- 

 ne<'tion with this formation, a number of investigations must be mention- 

 ed that have been made in Oil Creek Valley, from the nature of which 

 this stream has received its name. In 1860, examinations were carried 

 on at this locality with a vie"w to finding oil, small quantities of which 

 had been noticed floating on the creek.* 



Several shafts were sunk, yielding more or less oil during the past ten 

 years/a heavy quality of which seems to be existing in the hii>'her Me- 

 sozoic strata. Apparently the shafts were staitedoa Cretaceous ground, 

 and were continued through a series of shales, sandstones, and lime- 

 stones, with some yield of oil, until the red conglomerate was reached 



* The information upon this subject I owe to the courtesy of A. Rockfeller, esq., 

 of Canyon City, who kindly supplied me with the data, fcr which I wish to express 

 my thanks. 



