162 GUIDEBOOK OF THE WESTERN UNITED STATES. 
Poncha Pass, which stands at an altitude of 9,059 feet, and then 
descends into San Luis Park. Curiously enough, this branch line, 
in the heart of the Colorado mountains, has one of the longest 
stretches of straight track in this country—52 miles without a curve. 
Poncha Pass is much lower than Marshall Pass, and the traveler may 
look down into it when he is part way up the mountain. 
Above Mears Junction the character of the valley is different in 
different parts, making the answer to the question whether it was 
occupied by ice somewhat dou 
About 2 miles above Mears Junction the valley is again wide and 
flat-bottomed and has all the features generally attributed to occupa- 
tion by ice. In this wide part of the valley the railroad crosses to 
the east side, where it runs for nearly a mile, and then swings across 
the creek and returns on the opposite slope. As the road curves 
across the creek the traveler may see by looking upstream that this 
branch of the valley is not broad or U-shaped and was therefore 
probably never occupied by ice. As the train climbs the west wa 
of the valley many interesting views of the features described spore 
come into sight. It turns in around the head of every ravine and then 
out around every projecting point, as shown in Plate LXIX, B, until 
finally it comes to the top of the hills that face the valley. On one 
the outermost point, of the moraine 
there is a sign marked “ Yard limit.” 
Here, then, is a fragment of a terminal 
moraine, which indicates that the 
valley above has been broadened and 
that a great glacier long ago gathered 
on some of the high peaks that border 
the headwaters of Poncha Creek and 
flowed down to this point. 
About a mile above Mears Junction 
the valley changes from a broad, flat- 
omed swale to a narrow rocky 
tion and built the terminal moraine a 
short distance below? It is not appar- 
ent from the train where this body of 
ice could have originated, but if the 
traveler could climb some of the low 
hills on the right he would find that 
they are composed of gravel and sand, 
and that instead of being the foothills 
of the mountain they are only low hills 
that separate Poncha Creek from the 
wider valley of a tributary on the 
bes sae, drains the valley between 
peaks and joins 
built and ‘that it extended vais otis 
main valley to the terminal moraine 
already described and then r Boies 
After a long interval it readvanced 
valley broadens a short distance far- 
ther up and has all the appearance of 
having been occupied by ice. This 
glacier came down the valley of the 
east fork, which has been scoured out 
until fs cross section is a symmetrical 
U. s glacier originated near Pon- 
cha eal and extended only a few hun- 
dred feet into the main yalley. 
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