504 / HARLEN BRETZ 



west of the Cascades. The hypothesis that submergence was 

 relatively less on this side of the range may therefore be entertained. 



Contemporaneity of submergence and glaciation is clearly 

 recorded east of the mountains. In contrast to this it seems clear 

 that in Puget Sound maximum submergence lagged much behind 

 maximum glaciation, highest water-levels not being reached until 

 the ice front had retreated at least 70 miles and probably more than 

 100 miles. 



Though the tides are felt during lower river stages 1 50 miles up 

 the Columbia, yet Astoria, a few miles inside the Columbia bar, 

 has a fresh-water harbor. The great volume of the Columbia, then 

 as now, doubtless maintained the fresh-water character of the entire 

 submergence. The downstream journey of hundreds of miles by 

 bergs also indicates a current sufficient to offset the influence of the 

 prevailing westerly winds on these bergs. This fresh-water char- 

 acter of the Columbia submergence explains the absence of marine 

 shells in Willamette Valley such as those deposited in Puget Sound 

 during the same epoch. 



From the positive evidence of stranded bowlders the sub- 

 inergence reached a known maximum of 1,283 f^et A.T. close to the 

 Okanogan Lobe. Its known maximum at The Dalles was 1,200 

 feet A.T. The Dalles is 125 miles south of the Okanogan Lobe. . 

 On the west side of the Cascades the highest records of the sub- 

 mergence in Puget Sound are 290 feet A.T., and bowlders at 250 

 feet are reported near Corvallis, Oregon, 160 miles south of the 

 front of the Puget Sound Lobe. . 



Thus there is no evidence in Oregon and Washington for warpiilg 

 along lines parallel to the general front of the Cordilleran ice sheet, 

 nor in central Washington, for progressive submergence of the 

 glaciated area during retreat of the ice. In fact the entire sub- 

 mergence, save in Puget Sound Valley, was confined to territory 

 beyond the limits of glaciation. 



Isostatic depression 125 to 150 miles beyond the extremity of 

 the two most extended lobes, and this without detectible warping, 

 seems an impossibility. Furthermore, the apparent warping along 

 a north-south hinge line in the Cascade Range is wholly out of 

 harmony with isostatic adjustment during deglaciation. The sub- 

 mergence, therefore, is referred to diastrophic movements of greater 



