PEALE.] 



GEOLOGY SECTION NO. 15. 227 



glomeritic sandstone, which continues only a short distance, anrl 

 then we have volcanic again, which continues over the summit until 

 we again find on the opposite slope the sandstone. There is another 

 rise. Then we have volcanic again, and then sandstone and vol- 

 canic rock alternately for about half a mile, when, in a greater 

 depression than the previous ones, we meet with, first, a coarse sand- 

 stone, which becomes fine-grained, somewhat shaly toward the top. It 

 is followed by a red micaceous laminated sandstone at the point B, 

 These beds all dip east at an angle of abotit 15°. They all seem to lie 

 in the lap, as it were, of the volcanic rock which is pushed up through 

 them. This is shown in the illustration Fig. 3, Plate VI. On the north- 

 ern slope of one of the higher points (D) are fragments of a blue lime- 

 stone. Above it is volcanic rock, but I could not determine the order 

 of superposition. On the opposite side is a cliff-like wall about 6 feet 

 high. The volcanic rock seemed to overlie it, and at one point there 

 was a distinct dike about 2 feet in width, running through the lime- 

 stone. The volcanic rock seems to have been thrust up and spread out' 

 over the limestone. On the next slope are some coarse sandstones, 

 dipping toward the west. From this point the ridge continues to rise 

 gradually, and we have a long saddle-like depression connecting it with 

 Silver Heels Mountain. On the side of the next high point, in addition 

 to the beds already named, are — 



"1. Coarse sandstone. 



"2. Eed shale sandstone. 



"3. Conglomerate. 



"4. Sandstone. 



"These beds lie against the side of the hill, and dip to the northeast." 



The following section was made by Mr. Taggart on the ridge east of 

 Mount Lincoln, on the east side of the South Platte Eiver, and is in 

 ascending order : 



Section No. 15. 



1. Volcanic rock, which seems to reach to the timber-line, althougli 

 there are no distinct outcrops. The whole surface, however, is covered 

 with fragments of the rock. 



2. Coarse gray conglomeritic sandstone. 



On the summit of the next ridge we have — 



3. Volcanic rock in blocks. Then — 



4. Gray shaly sandstone, dijipiug to the , at an angle of about 



15°. This is about 3 feet thick. 



5. Eed shaly sandstone, about 6 feet. 



6. Fine gray sandstone, with small gray quartz pebbles. 



7. Volcanic rock in blocks as before. This exposure is on a hight?r 



point. 

 This section made by Mr. Taggart fills the gap between Mount Lin- 

 coln and section No. 9, made across the park, the profile of which is 

 shown in Fig. 1, Plate VI. This volcanic rock, to which reference has 

 boeu frequently made, is mostly ^rachytic, and although in many places 

 it has very much the appearance of being contemporary, I am of 

 the oi>iiiion that it is all intrusive. We find that where it is conforma- 

 ble to the sandstones and limestones the latter beds are always changed 

 on both sides of the volcanic material. We have already seen this in 

 the section made on Silver Heels, and we shall see it again in sections 

 made farther south. There are also, as we shall see in Buckskin Gulch 

 and in the canon of Four-Mile Creek, a number of faults and dikes, in 

 which everything points to tbe intrusive origin of the volcanic rock. 



