51 



THE COLUMBIA BASIN. 



In my work of unraveling the ecological facts of the Flathead 

 Lake region and western Montana some problems arose that I 

 could not solve there. It was established that the flora is almost 

 identical with that of the Blue Mts. of Oregon and the Cascades 

 though separated by the enormous barrier of the Columbia plains, 

 a barrier that in the Great Basin would mage marked changes in 

 the flora. A dubious explanation was possible in that much over- 

 worked theory of migration, around by the Bine Mts. and the Sel- 

 kirks, a slow process. Another disturbing geological problem was 

 the origin of the lake beaches so high up, at least 4200 ft. alt., 

 the base level being hardly 3000 ft., which has not been satisfacto- 



rily explained by Montana geologists. They have assumed a great 

 rock slide in the canon below Missoula or a glacial moraine dam- 

 ming back the water, but neither occurred, and in addition the 

 same beaches are found at the same level outside the Bitterroot 

 in the Flathead and Little Bitterroot and down the Missoula valley 

 to Thompson Fall* whore it debouches into the Columbia Basin 

 proper. 1 had no chance to carry the problem farther till 1911 

 when I traversed the whole Columbia Basin twice as fur as Cho- 

 paka Peak in the Cascades. I went from Pocatello Idaho down 

 Snake river valley, around the Blue Mts. to Spokane, thence to 

 the British border and along it to Oroville and Chopaka, thence 

 down the Okanogan and Columbia to Lake Chelan and Wenat- 



chee. 



Throughout the Columbia Basin at the north enormous glaciers 

 filled all valleys and the ice sheet capped most of the mountains 

 as is shown by the scorings going straight over the hills. This in- 

 sured the presence of a long line of great terminal moraines west 

 of Spokane under normal conditions. At Oroville, though lesa 

 than 100 i ft. alt. the glaciers had debouched far to the southward 

 leaving only local moraines and beautiful grma of lakes in every 

 nook, a geological Paradise. Anticipating a great treat I descen- 

 ded the Okanogan toward Chelan, expecting to soon come upon 

 the great moraines. All around were the benches even up to 4200 

 ft. alt., supposedly river terraces, but along the river it was sand 

 and everywhere in bars and benches, and the farther south I went 

 the more sand and less boulders, but no moraines terminal or lat- 

 eral to speak of, and so it was all the way down the Columbia to 

 Chelan. At Chelan Falls the Chelan glacier debouched and left 



