260 PROCEEDINGS OF THE CALIFORNIA 



The author went up the main branch of the Tuolumne river to its source in 

 the top of Mount Lyell, where, he had been told by Mr. Muir, there still ex- 

 isted a living glacier. 



The peaks of Mount Lyell group together form a vast amphitheatre, closed in 

 on all sides except in the direction of the Tuolumne meadows, by nearly perpen- 

 dicular walls. In this amphitheatre were formerly gathered the snows from 

 which issued the great Tuolumne glacier. Snow no longer fills the whole 

 amphitheatre, but still lies in vast masses in the more sheltered coves. These 

 masses are still in true glacial motion. The evidence of this is found in tlie ex- 

 istence of a perfect terminal moraine, semi-circular in form, one mile long, 

 twenty feet high, fifty feet wide at base, bounding the lower margin of the snow. 

 Additional evidence is found in the scattered blocks of stone on the snow, evi- 

 dently fallen from the cliffs of the amphitheatre, and on their way, in various 

 stages of advance, to join the terminal heaps. Mr. Muir planted a line of 

 stakes across the glacier in order to determine the rate of motion by subsequent 

 examination.* 



Thus it is evident, that on Mount Lyell we have still a glacier : perhaps not 

 what would at first strike one as a glacier — certainly not a typical glacier, 

 since there is no protrusion of an icy-tongue beyond the limits of the snow- 

 fountain — but still, in all essential respects a glacier, since there is true differ- 

 ential motion and a perfect terminal moraine. As the glacial period waned, 

 the Tuolumne glacier retreated step by step, until it retired within the snow- 

 fields of Mount Lyell and Mount McClure, but there it still exists in a state of 

 feeble vitality. The discovery of this important fact is due to Mr. John Muir. . 

 Mr. Muir has found hidden away, amongst the highest peaks of the Sierras, 

 several other snow-masses, which exhibit a similar feeble glacial vitality. 



3. Bloody Canon Glacier. — The Sierra, on the west side, slopes for sixty 

 miles, but on the east side very abruptly, so that the plain, four thousand feet to 

 seven thousand feet below, is reached in three or four miles. Long, complica- 

 ted glaciers, therefore, flowed down the western slope, while on the eastern side, 

 short, simple glaciers flowed in parallel streams down the steep incline and out 

 on the plains for several miles. The moraines of these streams can be well seen 

 from the top of any of the extinct volcanoes on the plains. One of these icy 

 streams flowed down Bloody Canon. Its track is beautifully scored and pol- 

 ished and rounded. The lateral moraines run out five or six miles on the plain, 

 as parallel ridges of debris, five hundred feet high. In this canon the two 

 kinds of glacial lakes are finely shown, viz., those which are found in the higher 

 valleys, and are rock-basins scooped out by the glacier, and those which are 

 found lower down and are formed by the gathering of water behind terminal mo- 

 raines. Also, the connection between these latter lakes and marshes and mea- 

 dows is shown, and the manner in which such lakes are gradually changed into 

 marshes and meadows. 



* The author subsequently learned from Mr. Muir, that after the lapse of forty-six days, 

 he found that the stake nearest the margin, No. 1, had advanced eleven inches ; No. 2, eight- 

 een inches ; No. 3, thirty-four inches, and No. i (near the middle), forty-seven inches. 



