DAVIS: GLACIATION OF THE SAWATCH RANGE. 5 
large as the ledges and knobs seem when one is on them, they sink 
to a subordinate rank when viewed from the higher mountain spurs. 
The knobs and ledges may be taken to be so many unfinished pieces 
of work, which would have been more completely scoured away 
had the glacial action lasted longer. It is therefore desirable to de- 
scribe glaciated troughs in terms of the degree of advancement that 
they reached while under glacial treatment. The faces of some of 
the larger residual knobs on the sides of the main trough showed 
well marked traces of nearly horizontal down-valley scouring and 
carving; that is, they bear the marks of having been shaped in ac- 
cordance with the movement of the heavy glacier that once occupied 
Fra. 4.— The glacial trough of Lake creek; looking west. 
the trough, and not of having been carved by normal erosive proc- 
esses which are now acting locally down the slope of the trough side. 
Features of the same kind are known on the sides of the Nor- 
wegian fiords; their analogy to the normal down-stream marks on 
the banks or sides of a water-stream channel have been pointed out. 
The openness of the Lake creek trough, figure 4, as seen from a 
high spur over its eastern end, and the absence of forward reaching 
spurs with overlapping ends, suggest the late maturity of a normally 
eroded valley; but the rocky floor of the main trough is not flat, as 
it would be in the late stage of a normal valley; the slender stream 
that now drains the trough has numerous rapids among the residual 
