DAVIS: GLACIATION OF THE SAWATCH RANGE. 3 
the sketches exaggerate the regularity of these features, and present 
them only in diagrammatic fashion; but they nevertheless are be- 
lieved to represent true and systematic relations. The small spurs 
are thought to be the result of accelerated subaerial erosion during the 
glacial period, a consequence of the widening and deepening of the 
trough below them; in any case, the sharp ridge and the little spurs 
with their ragged terminal facets have no likeness to the rounded, 
graded, subdued spurs of the neighboring non-glaciated lower moun- 
tains. The western side of the ridge descends into another trough, 
which must also have been occupied by a good-sized branch of the 
Twin lakes glacier; and the sharpness of the ridge is therefore to be 
Fig. 2.— Truncated spurs on the southside of Lake creek trough. 
attributed to its attack by glacial sapping on both sides. In the 
same way the sharpness of La Plata peak is to be attributed to glacial 
sapping in the cirque-head walls on all sides; and in this respect the 
sharpness of La Plata presents a most instructive contrast to the 
domed summit of Elbert, on whose higher shoulders a number of 
small glacial cirques were excavated, but not so far as to consume 
all of the normal summit form. Just as any statue must be smaller 
than the block from which it is carved, so the sharpened peak and 
spurs of La Plata (14,342’) must today be smaller and lower than 
the normal preglacial mass, whose form may have imitated and 
whose altitude may then have exceeded that of Elbert (14,424’). 
