GEOGRAPHY: W. M. DAVIS 
699 
mountainous highlands and perhaps still more to its being covered for 
most of its length by the waters of the lake that it ponded, as described 
below. The work of this long branch glacier in truncating the spurs of 
the adjoining mountain sides is conspicuous, and gives a peculiarly 
bold aspect to the valley that it ascended, but with decreasing effect 
up stream. It was these truncated spurs that caught the attention of 
the Transcontinental Excursion of the American Geographical Society, 
when our train ran down the valley from Missoula on the way to Spokane 
in 1912. We thus passed from the uppermost valley, where the side slopes 
FIG. 2. A TRUNCATED VALLEY-SmE SPUR, AT PARADISE, MONTANA, LOOKING NORTHWEST. 
have normally carved forms, and came unexpectedly on the marks of 
glacial scouring, faint and low at first, stronger and higher as we pro- 
ceeded, until the resulting spur-end cliffs gained heights of 500 or 1000 
feet, as in figures 2 and 3, and compelled the attention of all ob- 
servers; I returned there in 1913 for more deliberate study. The 
contrast between the smooth, maturely rounded forms of normal erosion 
on the higher, never-glaciated slopes and the ragged, immature cliffs 
of glacial scouring was as striking as it was persistent. Side valleys are 
occasionally barred by local moranic embankments, as in fig. 4, 
and holds swampy hollows behind them: the height of these moraines, 
