342 



CKOLOGV OF THE DENVER BASIN. 



In the vicinity of Burnt Knoll, which is the center of the slight 

 anticlinal rise in the axis of the Davidson syncline, the trend of the coal 

 outcrop becomes indefinite, but probably passes to the south of the knoll 

 and thence onward to the region of the Davidson hold just east, the old 

 Allen opening lying a short distance south-southeast of the knoll. 



At the northern or northwestern point of the Davidson mesa is a small 

 flat in which lies the coal of the Dunn and Davidson mines. 



The eastern rim. 1 n 1 1 1 U'dia tel v east of the above mines the Olltcrop of the 



coal measures, as an effect of erosion combined with a rise of the beds 

 against the southern arm of the Davidson fault, turns hack upon itself, 

 taking on its southward trend along the eastern rim of the sviicline. The 

 basal sandstones of the Laramie boldly outcrop a short distance southwest 

 of the mines, in the northwestern face of the mesa, their general strike 

 being X. l.V K.. their dip 25 ' W. The coal outcrops a little to their west. 



Flo. li Sei n. 

 stones "i Larami 



— ABOUT |!*s MILES. 



orosa .'".il benches of the Davidson : 



Davidson district. A, V,. Basal sand- 



A short distance southwest of the sandstone outcrops, on the eastern side of 

 the syncline, borings, of depths unlearned, are said to have revealed the 

 presence of .">. 4, and 5 foot seams of coal. From the above region the coal 

 horizon enters the mesa on the eastern side of the broad indentation in its 

 northern face, reappearing to the south, about the head of Marshall Gulch. 

 The basal sandstones of the Laramie form strong horizontal outcrops in the 

 railroad cuts and ditches just east of the divide in this vicinity, on the west 

 slope assuming a western dip of .V to 12°, which increases somewhat as 

 the center of the syncline is approached. Together with the coal measures 

 at tlie western end of the railroad cut, they now pass beneath the surface 

 into the valley below. 



In the ditches between the divide and Marshall Lake, in the eastern 

 half of the distance, the basal sandstones of the Laramie repeatedly outcrop 

 in practically horizontal position about 40 feet below the top of the mesa; 



