Glacial Phoiomena in Washifis^ton. — Dazcso?i. 
211 
Diagram No. 2. 
you are taken completely by surprise at finding yourself sud- 
denly deserted by the stream. This is, of course, a simple re- 
cessional phase, the lower valley having been occupied for a 
long time by a persistent ice mass. (Diagram No. 3.) 
Examples of the third class of coulees are the most numer- 
ous. The fact has already been referred to that the Chelan 
glacier found channels of discharge through a barrier range 
to the southward by means of Knapp's and Navarre's coulees. 
The latter of these is the larger and in some respects more 
remarkable, but the former has been more carefully studied 
and will be described briefly. An observer standing on the 
north side of lake Chelan across from the north end of Knapp's 
coulee sees a low divide cutting deeply through an east and 
west range of foothills, which rise from 1800 to 2500 feet 
above the level of the lake; cutting deeply, I say, yet not 
down to the lake level, for it ends, substantially, in a confu- 
sion of irregular terraces some 200 feet above the lake. Pass- 
ing through the four or five miles' length of this coulee, we 
find that the central portion is level for quite a distance, and 
is bounded by abrupt mountain walls, while the slope in either 
direction toward the ends of the valley is only four or five per 
cent. It is an ice-hewn valley, a discharge pipe of the Chelan 
glacier. Originally consisting of two opposite valleys heading 
at near the same point on the divide, it was selected by the 
