DENVER & RIO GRANDE WESTERN ROUTE. 



75 



West of the outcrop of the Morrison lies a red sandstone that is in 

 places at least a thousand feet thick. This sandstone is particularly 

 prominent about Manitou, in the valley of Fountain Creek, and for 

 this reason is called the Fountain formation. This sandstone is of 

 middle Carboniferous (Pennsylvanian) age. A limestone or gray 

 and pink dolomite -* about 100 feet thick and a sandstone of about 

 the same thickness lie below the Fountain formation. This sand- 

 stone rests on the granite of the Front Eange. All the rocks below 

 the Dakota sandstone are prevailingly red, and this color is well dis- 

 played in the valley west of the hogback. 



At Burnito siding may be seen some of the canals that carry water 

 to irrigate the valley below, as well as the pipe line which supplies 

 Canon City with water. The pipe line is high up on the north 

 (right), and the water is carried by gravity into a settling reservoir, 

 which may be seen on a hill to the right. Below the city aqueduct 

 is a canal, which is taken by a tunnel through the hogback to irri- 

 gate the orchards on the north side of the valley. On the south there 

 are two canals, one high up on the hillside and one near the level 

 of the river bottom. The higher canal receives its water from Grape 

 Creek, which enters the river just at the edge of the mountain ; the 

 lower one takes water from Arkansas River near the mouth of this 

 creek. 



A short distance above Burnito siding the traveler is face to face 

 with the imposing portal of the Koyal Gorge. (See PI. XXXIII, 

 B.) On the left is the old Hot Springs Hotel, now abandoned, and 

 on the right and considerably above the railroad are some small tun- 

 nels through which the city pipe line is carried. The passage seems 

 almost barred by the great slab of gneiss which projects from the 

 north and stands 400 or 500 feet high. The traveler may imagine 

 that the train will at once plunge into the shadowy depths of the 

 mighty gorge, but after passing the portal he finds that the canyon, 

 though rocky, is not particularly rugged or precipitous. 



The observant traveler will soon notice that there is close connec- 

 tion between the character of the rock and the shape and narrow- 

 ness of the gorge. Where the rock is massive granite cut by few 

 joint planes the gorge is narrow, but where the rock is intricately 

 banded and composed of many layers of diverse appearing rocks it 

 is wider and the slopes are more gentle. The differences in the form 

 and width of the canyon are due to differences in the resistance which 

 the various kinds of rock have offered to the cutting power of the 

 stream and to the processes of weathering. 



-*A. dolomite is generally regarded 

 as a limestone, but a limestone con- 

 sists essentially of carbonate of lime, 

 and a dolomite of double carbonate of 



lime and magnesia, containing 55 to 65 

 per cent of carbonate of lime and 35 

 to 45 per cent of carbonate of mag- 

 nesia. 



