698 
GEOGRAPHY: W. M. DAVIS 
The western glacier may be named after two deep lakes, Kootenay 
and Pend Oreille, the basins of which it excavated, one to the north, the 
other to the south of the international boundary. Lake Kootenay is a 
superb sheet of water of simple outline, ocupying an elongated and 
greatly overdeepened trough-basin between high mountain slopes char- 
acterized by strongly truncated spur-ends and hanging side- valleys; 
its length is much decreased by the long delta-plain of Kootenay river, 
which enters the lake from the south after a long detour through Mon- 
tana from the Rocky mountain trough in which its sources lie; the same 
river, as the lake outlet, turns westward at mid-length of the lake 
trough, where a distributary branch of the main glacier scoured out a 
side trough of catenary cross-profile, with fine hanging side-valleys, but 
probably 1000 feet less deep than the main trough which holds the lake. 
Lake Pend Oreille occupies a deep basin of the same kind, that was 
excavated between two mountain ranges in Montana by the middle 
one of three terminal branches into which the Kootenay-Pend Oreille 
glacier was there divided: this lake has been encroached upon by heavy 
morainic and outwash deposits on the north, which aid in separating 
it from Lake Kootenay. Huge volumes of gravel were washed south- 
westward from the terminal moraine at the farther end of Lake Pend 
Oreille, and now form a terraced intermont plain for 30 or more miles 
as far as Spokane: several side valleys in the adjoining mountains were 
barred by the outwashed gravels and now hold lakes, of which the largest 
is Lake Coeur d'Alene. 
Clark fork enters the east side of the broad northern end of Lake Pend 
Oreille where an arm of the lake would probably have a length of ten 
or more miles up the river valley but for inwashed gravels; the river 
flows out from the west side. The two parts of the river, above and 
below the lake, may be referred to as upper and lower Clark fork. The 
shortest of the three branches in which the Kootenay-Pend Oreille 
glacier ended moved westward a score of miles down the valley of lower 
Clark fork, and supplied the valley beyond its end with a great volume 
of outwashed gravels, now terraced by the river. 
The southeastern terminal branch of the Kootenay-Pend Oreille 
glacier was remarkable for its long course up the valley of upper Clark 
fork for 100 miles: its width may have been 10 miles or more near the 
point of its outbranching, but for much of its length it was less than 5 
and sometimes less than 2 miles wide: its greater extension than that of 
the western branch was probably due to better enclosure between 
