In contrast to the conclusions arrived at by Prof. Whitney, I extract from Prof. Le Conte’s Elements of Geology, pages 526 and 527, the following: “1st. During the epoch spoken of (the glacial) a great glacier, receiving its tributaries from Mount Hoffman, Cathedral Peaks, Mount Lyell and Mount Clark groups, filled Yosemite valley, and passed down Merced canyon. The evidences are clear everywhere, but especially in the upper valleys, where the ice action lingered longest. 2nd. At the same time tributaries from Mount Dana, Mono Pass, and Mount Lyell met at the Tuolumne meadows to form an immense glacier which, overflowing its bounds a little below Soda springs, sent a branch down the Ten-ie-ya canyon to join the Yosemite glacier, while the main current flowed down the Tuolumne canyon and through the Hetch-Hetchy valley. Knobs of granite 500 to 800 feet high, standing in its pathway, were enveloped and swept over, and are now left round and polished and scored in the most perfect manner. This glacier was at least 40 miles long and 1,000 feet thick, for its stranded lateral-moraines may be traced so high along the slopes of the bounding mountains.” In an article by John Muir, published in the New York _Tribune_, and kindly furnished me by Prof. Kneeland, will be seen views differing from those of Prof. Whitney, but Mr. Muir has spent long years of study upon the glacial summits of the Sierras, and if an enthusiast, is certainly a close student of nature. The paper was written to his friend Prof. Kunkle, of Boston, who had views similar to his own. Mr. Muir says: “I have been over my glacial territory, and am surprised to find it so small and fragmentary. The work of ancient ice which you and I explored, and which we were going to christen ‘Glacial System of the Merced’ is only a few tiny topmost branches of one tree, in a vast glacial forest. “All of the magnificent mountain truths that we read together last Autumn are only beginning sentences in the grand Sierra Nevada volume. The Merced ice basin was bounded by the summits of the main range and by the spurs which once reached to the summits, viz.: the Hoffman and Obelisk ranges. In this basin not one island existed; all of its highest peaks were washed and overflowed by the ice--Starr King, South Dome and all. Vast ice currents broke over into the Merced basin, and most of the Tuolumne ice had to cross the great Tuolumne canyon.