Fig. 10.—Iceberg in the Antarctic Ocean.
North America.—In North America living glaciers begin to appear in the Sierra Nevada Mountains, in the vicinity of the Yosemite Park, in central California. Here the conditions necessary for the production of glaciers are favourable, namely, a high altitude, snow-fields of considerable extent, and unobstructed exposure to the moisture-laden currents of air from the Pacific Ocean. Sixteen glaciers of small size have been noted among the summits to the east of the Yosemite; but none of them descend much below the eleven-thousand-foot line, and none of them are over a mile in length. Indeed, they are so small, and their motion is so slight, that it is a question whether or not they are to be classed with true glaciers.
Owing to the comparatively low elevation of the Sierra Nevada north of Tuolumne County, California, no other living glaciers are found until reaching Mount Shasta, in the extreme northern part of the State. This is a volcanic peak, rising fourteen thousand five hundred feet above the sea, and having no peaks within forty miles of it as high as ten thousand feet; yet so abundant is the snow-fall that as many as five glaciers are found upon its northern side, some of them being as much as three miles long and extending as low down as the eight-thousand-foot level. Upon the southern side glaciers are so completely absent that Professor Whitney ascended the mountain and remained in perfect ignorance of its glacial system. In 1870 Mr. Clarence King first discovered and described them on the northern side.
North of California glaciers characterise the Cascade Range in increasing numbers all the way to the Alaskan Peninsula. They are to be found upon Diamond Peak, the Three Sisters, Mount Jefferson, and Mount Hood, in Oregon, and appear in still larger proportions upon the flanks of Mount Rainier (or Tacoma) and Mount Baker, in the State of Washington. The glacier at the head of the White River Valley is upon the north side of Rainier, and is the largest one upon that mountain, reaching down to within five thousand feet of the sea-level, and being ten miles or more in length. All the streams which descend the valleys upon this mountain are charged with the milky-coloured water which betrays their glacial origin.
Fig. 11.—Map of Southeastern Alaska. The arrow-points mark glaciers.