178 GEOLOGY OF THE DENVER BASIN. 



the line of profile are represented by almost normal conglomerate, vertically 

 and laterally, with the appearance of bowlders in increasing quantity. The 

 dip of the sandstone above the jet layer is 18°. Approaching the summit, 

 the bowlders are larger and the conglomerate of which they are a part 

 becomes looser anil looser, until it is difficull in places to sec that regularly 

 stratified deposits arc to he recognized in the heap of bowlders. On a 

 glance at a considerable face of the exposure, however, the stratification is 

 alw a\ s plain. 



Andesite continues to he a marked element of the conglomerate to the 

 \er\ top of the series, hut the variety formerly noticeable is now no Longer 

 a feature. The rock prevailingly represented here is a dense pyroxene- 

 andesite in which the microscope shows both augite and hypersthene. The 

 amount ol' Dakota conglomerate pebbles and bowlders is larger than below, 

 while red and white sandstones are also present in considerable number. 

 .1 ust on the edge ol' the exposure is a large, white bowlder, G feet in 

 diameter, of a felsitic eruptive rock not identified in any lower horizon. 

 This may he an erratic, and it is also possible that glacial howlders may 

 he mingled with those of the coarse conglomerate on the upper slopes of 

 the mountain. 



Distribution of particular beds. — In speaking of the liinii of tlie mountain it 

 was said that at a certain level the low, gentle slopes or approaches gave 

 way to steeper ones. This line is approximately the base of die heavy 

 conglomerate series. On following up almost any one of the ravines 

 penetrating the mountain, outcrops representing the lower 100 feet of this 



COngh 'rate may he found in the stream bed or on the adjacent slopes, 



and the larger ridges practically terminate at the same horizon. Those 

 ravines leading south into Bear ('reek usually show the dark conglomerate 



of I') as soon as they have cut down sufficiently to bring it to the surface, 

 and this occurs halfway or more down to the creek. The gentle slopes 

 ahout the mountain are then, for the most part, in the series of fine-grained 

 sandstones or clays of the Division < ', above described, and, except for the 

 local development of a conglomeritic layer, there are few conspicuous 

 outcrops, although the beds of almost all water courses reveal clayey strata 



