219 



taiu Creek, and is underlaid with Upper Cretaceous beds, Nos. 4 an d 5, with 

 a thick covering of rather coarse drift. This is a most beautiful plateau, 

 overlooking the plain country in every direction. At the point of the 

 mesa, at the left hand, the two creeks unite ; only Cretaceous clays of 

 oSTos. 4. and 5 are seen. 



The Lignitic beds pass very soon beneath a more modern group of 

 rocks, which in the annual report of the survey for 1869 I called the 

 Monument Creek group. North and west of Colorado Springs are a num- 

 ber of extensive coal-beds, and in the sandstones above and below a con- 

 siderable variety of the peculiar fossil plants have been observed. We 

 know that a great thickness of the Lignitic group is here represented, 

 and in following the valley of the Monument Creek up to the northward 

 no want of conformity between the Lignitic and the Monument Creek 

 groups could be observed. I do not doubt, however, that on the "di- 

 vide" between the drainage of the Arkansas and the South Platte 

 Rivers there is a group of beds of quite modern date entirely distinct 

 from the Lignitic group, which must bear the name of Monument Creek 

 group. I desire here to correct a statement in Bulletin No. 3, page 210, 

 that the two groups, could possibly be identical ; also to correct the de- 

 scription of Plate VIT, which is an illustration of the more modern group. 



In all cases where I have observed the Lignitic strata near the base of 

 a mountain range, they have partaken fully of the uplift, and incline at 

 high angles usually from the range, but it is not an uncommon thing 

 for the modern Tertiaries to jut up against the granites, or to incline at 

 small angles, from 5° to 15"^. It was on this account that I pronounced 

 the Monument Creek group, in 1869, Middle Tertiary or Miocene, and, 

 although differing in lithological character, probably contemporaneous 

 with the White Kiver group farther to the northward, and holding the 

 same relations to the mountain ranges. Professor Cope, in the annual re- 

 port for 1873, page 430, says that the few vertebrate remains which he 

 discovered in this group show conclusively that it is newer than the 

 Eocene. We know but little of this modern group as yet, and we hope 

 hereafter to secure more definite evidence of its age as well as its rela- 

 tions to the South Park basin and other lake-basins in the West. 



If we look closely under the mountains, about the middle of the 

 profile, we shall see the upturned edges of the sandstones that form 

 a portion of the celebrated "Garden of the Gods." The brick-red sand- 

 stones are probably better shown here than at any other locality, and 

 the unique forms which they have received from atmospheric erosion 

 have earned for them their peculiar appellation. In the annual report 

 for 1873, opposite page 200, is a pictorial and anatomical section, which 

 strikingly illustrates the position of the rocks in this region. It will aid 

 the reader much in understanding thisprofile to read this report. To the 

 left of y there is a ridge, lapping on to the side of the mountain, elevated 

 at a high angle, with four cone-shaped j)oints; these are Silurian lime- 

 stones, which are well exposed in the vicinity of Manitou, near the source 

 of Fountain Creek. Above this point the Monument Creek group juts up 

 against the granites, concealing all the formations of older date. The 

 lessons taught by this profile are much the same as those so well shown 

 in the preceding plate, IX. The mountains seem to rise abruptly out of the 

 plains, as if the vast granitic Inasses had pushed their way up vertically 

 through the overlying crust, or sedimentary group of beds. At the very 

 base of the mountains, for a portion of the distance, the entire group of 

 sedimentary beds is tipped up at various angles, but in a very short 

 distance eastward from the range only the coal group is seen in a hori- 

 zontal position. The peculiar forms, both in the mountains and the 



