136 LAKES OF NOItTH AMERICA. 



water-filled, continues beyond the head of the lake for a distance of at 

 least twenty-five miles, becoming more and more wild and rugged as it 

 nears the heart of the highlands. The total length of this remarkable 

 valley is not less than one hundred miles, and its width at the level of the 

 htke seldom exceeds four miles. 



The sounding line has shown that Lake Chelan is over eleven hundred 

 feet deep, but its full depth remains to be determined. In several sound- 

 ings made by the writer in its central and western portions, no bottom 

 was reached at the depth indicated. The surface of the lake is but 950 

 feet above the sea, so that the bottom of the trough is below sea level. 



Where the clear water of the lake washes the precipitous walls enclos- 

 ino- it there is no beach, and scarcely a trace on the rocks to show that it 

 has altered the topography of the shores. The present conditions were 

 initiated at such a recent date that, practically, the only changes they have 

 produced are at the eastern end of the lake, where it emerges from the 

 rocky defile of the mountains and for a short space expands between com- 

 paratively low shores of gravel and sand. In this region high terraces 

 mark the former level of the water surface. 



How the great gash in the mountain, fully one hundred miles long, 

 and now filled for more than a thousand feet in depth by the lake, was 

 formed, is not easy to explain. Previous to the birth of -the present lake 

 the valley was occupied by a large glacier which flowed through it and 

 joined another great ice stream in the carion of the Columbia. The ice 

 smoothed the precipices of rock and piled up moraines on the more gentle 

 slopes at the east end of the valley, but that the main depression existed 

 before the glacial invasion is evident and is in harmony with the histories 

 of many other valleys in the Cordilleran region. The valley has a still 

 more ancient history, and in Tertiary, or in part perhaps in pre-Tertiary 

 times, was excavated in the hard granite, now seen in its enclosing walls, 

 by the slow wear of streams. It is a stream-cut channel, but where the 

 stream rose that did the work, or whence it flowed, remains to be deter- 

 mined by a careful study of all the facts bearing on the problem. 



It has been the writer's fortune to pitch his camp on the borders of both 

 Lake Tahoe and Lake Chelan. As the scenery of each is conjured up in 

 revery, it is difficult to decide which is the more remarkable or which 

 should have the first rank among the mountain lakes of America. Each 

 lake is surrounded by forest-covered mountains of majestic proportions 

 and rich and varied details ; the waters of each lake are clear and deep in 

 color, or varied by silvery reflections and iridescent tints where the not 



