DENVER & RIO GRANDE WESTERN ROUTE. 83 
had been occupied by the stream for a longer time than the Royal 
Gorge.?* 
The walls of the canyon from its mouth just above Parkdale to 
Texas Creek are generally uniform in height, so that this canyon 
also appears to have been cut in a plateau, the 
Texas Creek. surface of which was originally gently rolling. 
ee oo: feet. At Texas Creek a branch of the railroad turns to 
Denver 184 miles, the south (left), crosses the river, and after run- 
ning up a small valley for a short distance i in order 
to obtain grade, turns back and loops around a projecting spur con- 
siderably above the bottom of the valley. After passing this spur 
the road follows for a long distance the valley of Texas Creek on its 
way to the mining district of Westcliffe, 25 miles distant. 
Near the station of Texas Creek the canyon takes on a different 
aspect. It becomes much broader than it is east of that place, and 
though the walls may in places be precipitous, they are generally 
smoother and gentler in their slope than they are farther east. This 
part of the canyon looks older than the part below, and it is also 
different from the part above. On leaving Texas Creek the train 
heads directly toward the great Sangre de Cristo Range (P1. XLIIT) 
d at a point 3 miles above Texas Creek swings abruptly to the © 
an 
right, following Arkansas River, which here leaves the broad valley 
in which it has been flowing, and in a short distance it again enters 
a canyon, some parts of which are steep and narrow. If the traveler 
looks to the left as the turn is made he will see that the broad valley 
continues directly toward the high mountain peaks but is occupied 
only by Oak Creek, a stream not at all commensurate in size with that 
of the valley which it occupies. The meaning of these differences 
* Geologists imrnred classify the | may differ considerably in age, so 
Surface features of the earth accord- | there are young canyons and old can- 
ing to their sod or ecanaltie to the | yons. In canyons of these two classes 
length of time they have been in the | that are cut in essentially the same 
tains, young valleys and old valleys, | toms, which are generally but little 
and young streams and old streams. | wider than the channel of the stream, 
Where the rocks are fairly uniform | and by having walls that are commonly 
i aaa the youngest type of valley | steep and in many places precipitous. 
on and the oldest is the | Old canyons, on the other hand, are 
Ry valley with slopes so gentle that | generally wide’ enough, at least in 
it almost resembles a plain. A can- | places, to have narrow strips of flood 
yon is considered young because it | plain; their walls are less precipi- 
marks the first stage in valley cut- | tous, and their rocks are generally 
ting; a broad valley is considered old | more irregular in outline owing to 
it marks its last stage. | the fact that they have been longer 
Although all canyons are young, they | exposed to the weather. 
‘ 
