EXTENT OF THE CORDILLERAN ICE-SHEET 429 
and gravel; and the streams flowing into the lake tumble over 
bowlder beds between banks of gravel and sand. It is noteworthy, 
however, that none of this detrital material—that separating the 
two lakes, that filling the main valley south of the lower lake, and 
that in the tributary valleys—shows any sign of morainal topog- 
raphy. It is arranged in terraces, somewhat modified by later 
erosion, but still forming distinctly flat-topped benches, and the 
bowlders and cobbles found in it indicate, by their partly rounded 
shape and the lack of striae, wear by water. The obvious con- 
clusion is that upon the retreat of the ice this comparatively narrow 
valley was filled by a swollen, swiftly flowing stream that completely 
rearranged the morainal material. Mr. Calkins’ has noted cases 
of similar reworking of glacial deposits east of here, but he found 
traces of true moraine. I know of no description of reworking of 
glacial deposits by stream action comparable in completeness to 
that at Priest Lake. An entirely similar condition was found at 
Sullivan Lake, a small mountain lake in Washington draining into 
the Pend d’Oreille River. 
Having established the former existence of ice over the divide 
between the Pend d’Oreille and Priest Lake valleys, and its limita- 
tion on the east by the Priest Lake—Kootenai divide, we may con- 
sider the southern extent of this lobe. The Kootenai lobe probably 
extended to the southeastern lobe of Lake Pend d’Oreille,? but 
probably no farther, for there is no evidence of continental glacia- 
tion in the Coeur d’Alene Mountains immediately south of this 
lake. Glacial striae have been found at Cocollala, west of Lake 
Pend d’Oreille at an elevation of at least 200 feet above the lake.* 
It therefore seems probable that the ice of the Kootenai lobe, held 
back by the Coeur d’Alene Mountains on the south, spread west- 
ward down the Pend d’Oreille valley, and united with the Pend 
d’Oreille—Priest River lobe. The southern limit of the ice formed 
by the union of these two lobes was somewhere north of the outlet 
of Lake Coeur d’Alene if the conclusion that the gravel found there 
is an outwash plain is correct. It is possible, however, that this 
U.S. Geol. Surv. Bull. 384. 
? Calkins, zbid., p. 32. 
3T. C. Chamberlin, U.S. Geol. Surv., 7th Ann. Rept. 
