Note H — INTERNAL STRUCTURE AND PROGRESSION OF THE GLACIER.

"During the winter, the temperature at the surface of the glacier sinks a great many degrees below 32° Fahrenheit, and this low temperature penetrates, though at a gradually decreasing rate, into the interior of the mass. The glacier becomes fissured in consequence of the contraction resulting from this cooling process. The cracks remain open at first, and contribute to lower the temperature of the glacier by favoring the introduction of the cold air from without; but in the spring, when the rays of the sun raise the temperature of the snow covering the glacier, they first bring it back to 32° Fahrenheit, and presently produce water at 32°, which falls into the chilled and fissured mass of the glacier. There this water is instantly frozen, releasing heat which tends to bring back the glacier to the temperature of 32°; and this process continues till the entire mass of the cooled glacier returns to the temperature of 32°."