DENVER & RIO GRANDE WESTERN ROUTE. 133 
the warm springs which gush from the same formation at Glenwood 
Springs and give that place its reputation. Why the water should 
be warm at both these places is a question that can not yet be an- 
swered, for neither spring has any apparent connection with a fault 
that would permit the hot waters to rise from great depths, or with 
old volcanic flows or vents in which circulating water would come 
into contact with rocks that still retain some of the heat they had 
when they were ejected from the earth’s interior. However, there 
may be some underground connection with one or the other of these 
features which is not apparent at the surface but which would 
account for the temperature of the waters carried in this limestone. 
The limestone rises toward the west at an angle of about 15°, and 
within a distance of half a mile the underlying quartzite appears 
at the level of the track. As the river cuts deeper and deeper into 
the rising rocks the canyon becomes more and more rugged, and the 
short bends give rise to many towers and pinnacles upon the pro- 
jecting points. As the rocks continue to rise in the direction in 
Which the train is going, lower and lower rocks come into view. 
Next below the upper quartzite, which is about 100 feet thick, lie 
Shale and thin-bedded sandstone, about 40 feet thick, and upon these 
lies white quartzite, about 270 feet thick. So far the section in this 
canyon is almost identical with that seen in the deeper canyons up 
Eagle River, but here there is still another member, which seems not 
to be present farther east. This member is a coarse quartzite whose 
chief characteristics are its rich pink or maroon color and the re- 
markable regularity in the thickness of its various beds, as well as 
the evenness of the bedding planes which separate them. These 
characteristics are well shown in Plate LVII, B. The full thick- 
hess of this quartzite can not be seen here, for within a short dis- 
tance the beds dip sharply in the other direction and the quartzite 
disappears below water level. Farther down the river, however, | 
where the quartzite rests on the granite, its thickness is about 80 
feet. The highest point on this arch in the rocks is reached about 
half a mile beyond milepost 346. Beyond this point the beds dip 
rather steeply downstream until the Leadville limestone is at track 
level on the left, and then the whole series is broken by a great fault, 
Which, as shown on the map, crosses the railroad at milepost 347. 
Beyond the fault the land on both sides of the river 18, COMMpars- 
tively low and smooth, and then the Leadville limestone rises again 
from track level. Where it is seen by the roadside it is much broken, 
having evidently been greatly disturbed and crushed. The rise of 
the formations downstream is gradual but steady, so that near mile- 
~ post 349 all the sedimentary rocks are again above water level and 
the granite makes its appearance. Plate LVII1 isreproduced from 
80697°—22-__10 
