DENVER & RIO GRANDE WESTERN ROUTE. 161 
through ridges and spurs of gravel and boulders which constitute a 
part of the high terrace already mentioned. Near milepost 222 it 
enters the canyon which Poncha Creek has cut in the hard rocks that 
compose the mountains. 
A quarter of a mile above milepost 223 the railroad swings to the 
left in a broad curve around a mass of loose material which has been 
swept down from a small gulch on the right, and almost immediately 
after swinging back into its normal position it has to make another 
curve in order to pass a 
second mass of similar 
loose material. Such 
masses, if fairly flat, are © 
known as alluvial fans, 
but if steep they are 
called alluvial cones. 
The fans in Poncha 
Canyon are shown in 
the accompanying dia- 
gram (fig. 42). On the 
first fan the radial lines 
occupied by the streams Ficure 42. ee fans in » Ponda Canyon, 
ma. 
ioral that has been swep t of vines in the 
at different times can ountains is pees out fs semicircular fans, which 
easily be seen from the 
fhe railroad is obliged to pass around in two sharp 
. urves. 
train, as they are marked 
by straight depressions and by ridges of boulders and angular pieces 
of broken rock which have been swept down by the stream. 
The canyon is narrow and V-shaped as far as Mears Junction, 
where it abruptly changes to a rather broad valley with a flat, 
SrAnDE bottom, which bears all the marks of hav- 
Mears Junction. g been occupied by moving ice—that is, by a 
Elevation 8,431 feet. ilroad 
Denver 226 miles ate #° At Mears Junction a branch railroa 
turns to the right and after circling about over the 
Main line turns back on the left and climbs the mountain slope to 
a moraine in a narrow valley may be 
the 
“A glacier that occupies a rather 
Af ost in- | more or less washed away by 
Variably builds q ridge at its lower | stream after the isa 
end, composed of fragmen it examination of, the side of 
; the valley below Mears Junction shows 
Died by ice it should contain some 
trace of a terminal moraine, although 
(left) wall of the valley and causes 
e stream and the d to curve 
to Tae right in order to pass 1. A 
the point where the railroad rounds 
