. Elements of geology : a text-book for colleges and for the general reader. Geology. 52 AQUEOUS AGENCIES. surrounding ice, because more absorbent of beat, and tbus form deep holes. An admirable illustration of extreme inequality of the surface of ice is seen in the case of the small residual glacier still remaining on. r"3s^> — Fig. 40.—Ice-Pillars on Parker Creek Glacier, California (after Russell). Mount Lyell, Sierra Nevada.* On the top of Mount Lyell there is an immense amphitheatre (cirque), filled with snow and ice. In August the surface of this ice-field is set with ice-blades,
. Elements of geology : a text-book for colleges and for the general reader. Geology. 52 AQUEOUS AGENCIES. surrounding ice, because more absorbent of beat, and tbus form deep holes. An admirable illustration of extreme inequality of the surface of ice is seen in the case of the small residual glacier still remaining on. r"3s^> — Fig. 40.—Ice-Pillars on Parker Creek Glacier, California (after Russell). Mount Lyell, Sierra Nevada.* On the top of Mount Lyell there is an immense amphitheatre (cirque), filled with snow and ice. In August the surface of this ice-field is set with ice-blades, three to four feet high and only two feet apart, as in the section Fig. 41. They are probably formed as follows: In winter, when the snow is deep and light, it is blown into wind-ripples on a large scale. These soon become fixed by surface melting and freez- ing, and then the greater action of the sun in the troughs, partly by the reverber- ation of heat and partly by accumulation of dust there, causes these to become deeper and deeper. It is necessary to re- member that there is little snow or rain in this region after about the first of May until November. Again, fissures or crevasses, often of great size, ten to twenty feet wide, one hundred feet deep, and sometimes running entirely across the glacier, are very abundant. As the surface of the glacier is often cov- ered with snow, and the fissures thus concealed, they form the most dangerous feature connected with Alpine travel. The law which gov- erns their formation will be discussed hereafter; suffice it to say that. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original LeConte, Joseph, 1823-1901. New York : D. Appleton and Co.
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