40 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



of Purgatory Creek he caught sight of Pikes Peak, far to the north. 

 Pike, in his journal, calls it the " Grand Peak." He was fired with 



Jnst to the east of the gateway to 

 the Garden of the Gods the gjT)Sum 

 layer of the Lykins formation is prom- 

 inent. (See PI. XIX.) This gypsum 

 undoubtedly crystallized out of a land- 

 locked body of sea water which had 

 been reduced by evaporation in an 

 arid climate to a state of supgrsatu- 

 ration. Gypsum, a mineral so soft 

 that it can be scratched by the finger 

 nail, is used in making wall plaster 

 and as a fertilizer. The Morrison for- 

 mation, which is made up chiefly of 

 maroon and green limy shale, is best 

 seen near Colorado City in the rail- 

 road cut just east of Quarry Spur, 

 This formation, which generally ex- 

 tends along the Rocky Mountain 

 Front, has yielded many bones of 

 huge reptiles, such as the Ceratopsia. 

 One skeleton was found in the Garden 

 of the Gods. This is the same band 

 of rock in which remarkable reptilian 

 remains Avere found west of Denver 

 and north of Canon City. (See PI. 

 XXXII, B, p. 70.) 



To observe the outcrops of the for- 

 mations of Cretaceous age as high 

 in the column as the Niobrara forma- 

 tion it is necessary to leave the rail- 

 road track just west of Colorado City 

 and climb about 100 feet to the level 

 of the gravel bench. These outcrops 

 form perfectly straight hogback ridges 

 between Fountain Creek and Bear 

 Creek, and the beds in them stand 

 nearly vertical. The western hogback 

 is made up of Dakota sandstone and 

 the Lower Cretaceous rocks that are 

 associated with it. The eastern hog- 

 back carries along its crest the sand- 

 stone member of the Carlile formation 

 and the overlying Niobrara limestone, 

 which are also well exposed. 



The traveler should visit the mesa, 

 the large mass of gravel overlying the 

 PieiTe shale in the V between Monu- 

 ment and Fountain creeks. This is 

 but one of many remnants, all sloping 



away from the mountains at much the 

 same height, of a great deposit of 

 gravel which has been cut through by 

 such streams as Fountain Creek. One 

 who restores in his mind's eye from 

 mesa to mesa the gravel plain repre- 

 sented by the surface of these rem- 

 nants can get an idea of the former 

 extent of this stream-laid gravel, 

 which -was spread out by streams 

 flowing from the mountains, and can 

 understand the mode of formation of 

 the Dawson arkose, which was simi- 

 larly laid down millions of years 

 earlier than this gravel. 



To the south the ragged crest of 

 Cheyenne Mountain rises more than 

 2,0(X) feet above the sedimentary beds 

 at its eastern base. This sudden 

 change in the surface features is due 

 to the different rate of weathering of 

 the sedimentary beds and the great 

 granite mass, which was upraised 

 along the Ute Pass fault for more 

 than a mile and at the same time 

 thrust forward about 4 miles. By this 

 faulting movement the sedimentary 

 rocks between Manitou and the south- 

 ern end of Cheyenne Mountain were 

 sheared off as shown in figure 13 

 (p. 53). The detached masses of sedi- 

 mentary rock that once lay upon the 

 upthrown block of granite were car- 

 ried up with it and were long ago 

 worn away and lost by erosion. Plate 

 XXIV, B, and figure 13 show the Ute 

 Pass depression, which marks the 

 fault-line break where it continues 

 northwestward through the granite of 

 the Front Range. This is the greatest 

 fault or dislocation of the rocks in 

 the Colorado Springs region. As these 

 faulting movements took place in 

 geologically recent time the Rocky 

 Mountains, which were brought into 

 being by them, are therefore recent 

 features in the geologic sense. They 

 were probably raised up after the 

 deposition of the Dawson arkose. 



