BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
The trough of Clear creck, similar to that of Lake creek, but on 
the south of La Plata mountain, was seen from a high knob that 
rises on the east side of the Arkansas river, about three miles south 
of Granite. Here, as in the case of Lake creek, one may see the well 
formed trough with its catenary cross section — rather too steep on 
the sides in figure 5, — rising to the oversteepened slopes that trun- 
cate the mountain spurs on the north and south; while in the fore- 
ground two great lateral moraines stretch toward the river enclosing 
a meadow through which Clear creek meanders, instead of a pair 
of lakes, as is the case with the Twin lakes moraines. It is on ac- 
count of the strong forward reach of these moraines from the glaciers 
of the Sawatch range on the west, while no glaciets were formed 
here on the lower range to the east, that the Arkansas has been locally 
pushed against the eastern side of its preglacial valley, where it has 
undercut and steepened the mountain bases, and incised a gorge in 
the granites. As the railroads here follow the gorge, the traveller 
for a time gains no general view. To the south of the gorge, the 
Arkansas valley is much less encroached upon by moraines from the 
western range, and its broad wash-plain stretches unbroken for miles 
together; yet here also the river flows near the base of the eastern 
range, probably because of the greater height of the western range 
and the consequently greater supply of waste from that side. 
A fine view of the district south of the gorge is had from the trains 
of the Colorado Midland railroad, as they descend from the pass 
that leads from South park. Opposite the town of Buena Vista a 
grand view is offered of the Sawatch range, with Mt. Princeton 
(14,196’), a most shapely mass, in the center. A shallow, steeply 
inclined glaciated trough, heading in a small cirque and terminating 
in a morainic loop on the mountain flanks, is easily recognized on 
the northeast slope. The moraines that stretch out from the valley 
between Mts. Harvard and Yale are seen farther northwest. When 
I was in this region in 1869, a section of our party headed by 
Professors Whitney of Harvard and Brewer of Yale, crossed into 
the Arkansas valley from South park and ascended the Sawatch 
range, camping near the tree line for the two nights of the day 
on which we climbed Mt. Yale (14,187’). The following day was 
cloudy and wet and the Professors returned directly to the valley; 
but two of the younger members of the party were sent with 
barometer and compass across the deep valley between the peaks 
and up the northern mountain which was to be called Mt. Har- 
vard. Occasional breaks in the clouds gave us glimpses of the 
