DENVER & RIO GRANDE WESTERN ROUTE. 176 



sight of the station of Cimarron nestling beneath the spreading 

 branches of giant cottonwoods is therefore most 

 Cimarron. welcome. From the station it is impossible to de- 



Eievation 6,905 feet, termine wliy the canyon has come to an end and 

 Denver^329 miles. why one Can look out through the trees into open 

 country beyond. This change, like many others, is 

 due to the geology, and it can be better understood by the traveler 

 when he is at least part way up the long grade to Cerro Summit. At 

 Cimarron the automobile road on the south side of the river joins the 

 railroad, and together they climb to the summit on their way to Un- 

 compahgre Valley. 



Immediately after leaving Cimarron the traveler will see that, so 

 far as the surface features are concerned, he is in an entirely differ- 

 ent world. He has just passed through a region of the hardest rocks, 

 where he could see little if any soil, but here he can see no rock, at 



Figure 46. — Section across Black Canyon at Cimarron. Tlie rocks tiave broken along the 

 fault shown in the section, and the granite on the north has been forced up far above 

 its original position. 



least nothing that resembles the rocks of the canyon, though on closer 

 examination he will see that the rock is the softest kind of shale — the 

 Maneos shale. He may also notice that the contact between the rocks 

 of the canyon and those of the plain is extremely abrupt, and if he 

 could follow that contact he would find that the same beds are not 

 in contact at all places. This variability in contact indicates that 

 the rocks of the plain and those of the canyon are separated by a 

 fault. In other words, the hard rocks of the canyon have been 

 broken away from their fellows down below and lifted until they 

 now stand actually higher than the shale, as shown in figure 46. This 

 fault has been traced for a long distance, and in all places the edges 

 of the sedimentary rocks are in contact with the granite. (See PI. 

 LXXXVII, .4,5, p. 216.) 



After leaving Cimarron the train begins its steep climb to the 

 divide which separates the drainage of Cimarron Creek from that 

 of Uncompahgre River. This grade, which is one of the steepest 

 grades on the road, is 4 per cent, or 211 feet to the mile. In making 



