36 SURVEY OF COLORADO AND NEW MEXICO. 



the sandstones of Ko. 1, and a i^ortion of the red beds or triassic (?). 

 Still further west are two or three rather low ridges of yellowish-gray 

 and red sandstones, which cover the gneissoid rocks of the foot-hills 

 of the monntains. By far the largest ridge here is the one containing 

 the sandstones of E'o. 1, but it soon splits up into smaller ridges 

 in its southern extension. 



About four miles further south, in the cahon of JBear Creek and -Tur- 

 key Creek, there are fine exhibitions of the beds of upheaval. The 

 chalky shales of No. 3, with abundant specimens of Inoceramus prohle- 

 maticus and Ostrea conges f a, iorm a lowrounded ridge; then comes a nar- 

 row valley worn into the black shales of No. 2; and then a high ridge 

 of massive sandstone — No. 1 — inclining 30° to 35°. On the western 

 side of this ridge we see the projecting edges of the sandstone capping 

 the ridge, and underneath the variegated marls and sandstones, with 

 some of the brick-red beds. Then comes a series of rather low, rugged 

 ridges ; first a layer of sandstone and loose brick-red sand with gyp- 

 sum ; dip 29°. Second ridge, a light gray sandstone with a rusty, yel- 

 lowish tinge; dip 34°. Tlien come three or four small ridges of deeper 

 brick-red, or almost purplish red sandstone; dip 29°. The intervals be- 

 tween these ridges are composed of arenaceous shale. Among the red 

 sandstones are two thin layers of bluish limestone, which is burned into 

 lime. 



Tbe foot-hills of the mountains are composed of gneissoid rocks. They 

 form a wide belt or range below the main or Snowy Eauge, rising 1,500 

 to 2,000 feet above the unchanged rocks. These metamorphic ridges or 

 hills are w^ell grassed over in many instances, and rounded, and so cov- 

 ered with debris that it is almost impossible to see the layers in position. 



On the little creek there is a small mill for grinding the gypsum into 

 IDlaster for various economical purposes, and also for sawing the sand- 

 stone into forms for architectural purposes. The gypsum is amorphous, 

 but very white and pure, and would make tlie finest of casts and 

 moldings. Some of the layers are susceptible of a high polish like 

 the California marbles, only they are of a more uniform white color. 



Up among the foot-hills, good crops are raised, especiallj" all kinds of 

 garden vegetables. As fiue wheat as I have ever seen was growing on 

 Mr. JMorisson's farm, at an elevation of at least one thousand to fifteen 

 hundred feet above Denver. 



At Harriman's, on Turkey Creek, is an excellent place to observe the 

 junction of the sandstones and the gneissoid rocks, and I could not de- 

 termine that there was any discordance, the dip of all being 25° to 35°. 

 The slopes of the hills, as well as the rocks themselves, show the incli- 

 nation very clearly. The metamorphic rocks are distinctly stratified as 

 any sandstones, and we find alternate beds of syenite, mica schist, horn- 

 blende slate, coarse aggregated quartz, feldspar, and mica, regular gneis- 

 soid rocks, inclining at a high angle in the same direction as the sand- 

 stones. 



For a long distance there is an apparent conformability of the sedi- 

 mentary rocks to the metamorphic; but I am inclined to think that it 

 Is not real or permanent. Both north and south of this point the two 

 classes of rocks do not conform. 



Near the summit of the sandstone ridge No. 1, on Turkey Creek, there 

 is an asphaltum spring, which has been wrought for oil. A consider- 

 able thickness of the sandstone seems to be thoroughly saturated with 

 the pitch or bitumen, and between the layers of the sandstone are ac' 

 cumulations of the tar. This spring is located on the east side and near 

 the summit of the " hog-back." 



