218 



abundant, and it extends far out into the plains. To show its local 

 character we may state that the materials become gradually finer as we 

 recede from the' place of their origin. Toward the mountain crest or 

 divide, the local drift is very coarse, made up of blocks scarcely worn ; 

 these diminish in size and become more and more rounded by attrition 

 as we move from the crest. Pike's Peak, which towers so loftily over 

 all the other summits in the vicinity, is covered on its top and sides with 

 broken masses. High above timber-line, the sides of the jeak are 

 covered with a heavy thickness of glacial drift, forming a fine earth, upon 

 which a thick matting of grass and other herbaceous vegetation is 

 growing. Small lakes surrounded with morainal ridges occur above as 

 well as below timber-line. 



The sedimentary ridges along the foot of the mountains, as is shown 

 in the sketch, are cut through at right angles, at short distances, by the 

 numerous little streams that flow down from the mountains into the 

 plains. Most of these channels are dry the greater part of the year. 

 These also show that the erosive action has greatly decreased in modern 

 times. We may therefore infer that, so far as surface forms are con- 

 cerned, there has been nothing permanent but change; that the process 

 of degradation has gone on from the beginning with varied degrees of 

 power, and that it is going on now continually, but with greatly dimin- 

 ished force. 



In describing briefly Plate X, we may commence at the right hand or 

 north end ; we see in the distance the source of Monument Creek in the 

 divide which separates the drainage of the Arkansas Eiver from that of 

 the South Platte. The coarse sediments of the Monument Creek group 

 usually jut up against the granite foot-hills with very little inclina- 

 tion, as if the elevation had been very slight since the deposition of the 

 Monument Creek beds. In the foreground near the pine tree, are the 

 bluffs of Lignitic sandstones, which overlook the valley of Monument 

 Creek, and once extended across to the foot-hills of the mountains. 

 At n is "West Monument Creek, which, with its numerous branches, has 

 carved out broad valleys, as they came down from the mountains, 

 leaving, either in groups or isolated columns, those singular forms fig- 

 ured in the annual report for 1873, opposite page 32, and on this 

 account have suggested the name of Monument Park. At v we have 

 the isolated castellated columns seen in the heliotype Plate VII, in 

 Bulletin No. 3. About midway in the profile at 2?, are Austin's Bluffs, 

 a part of the coal or Lignitic series, dipping northeast at an angle 

 of about 8°, and extending off to the northwest, so as to lap on to the 

 granite foot-hills. At the left-hand corner, a portion of the same sand- 

 stones seen at the right-hand corner and in the center of the foreground, 

 are shown, with something of the peculiar style of weathering of the 

 Monument Park sandstones. The layer which caps the column, is an 

 iron-rust colored sandstone, harder and less yielding than the portions 

 below. The oxide of iron seems to have cemented the grains of 

 sand and small worn pebbles into a hard rock. Here we have the lowest 

 beds of the Lignitic group, and nine miles east of Colorado Springs, under- 

 neath these sandstones, are thick beds of coal, amounting in the aggregate 

 to 20 feet or more. In the valley of Monument Creek, t, t, the Cretaceous 

 clays are exposed by the denudation of the Lignitic beds, and numerous 

 species of Ammonites, Scaphites, Inocerami, &c., are found. These coal or 

 Lignitic beds once extended uninterruptedly across to a point very near 

 the base of the mountains, and in all probability were connected with the 

 coal-beds at CaGon City, on the Arkansas, a distance of thirty miles in an 

 air line, southwest. The mesa, fc, 7c, separates Monument Creek from Foun- 



