CHAPTER X
ON SOME OF THE PHENOMENA OF GLACIERS, WITH SPECIAL REGARD TO THOSE OF NEW ZEALAND
The cause of glaciers—Formation and structure—Motion—Moraines: Lateral, medial, and terminal—‘Surface’ moraines—Crevasses—Moulins—Glacier cones—Glacier tables—Surface torrents—Avalanches—Cornices
In a work of this nature it may not be out of place to briefly describe some of those interesting features and phenomena which accompany the world above the snow-line.
Here is a quotation from a recent review of Professor Heim’s work[2] by a prominent member of the English Alpine Club:—
‘Some thirty years ago a systematic résumé of all that was known up to that date about existing glaciers appeared in the work of Professor Albert Mousson, “Die Gletscher der Jetztzeit,” since which, with perhaps the exception of Major Hüber’s “Les Glaciers,” no attempt has been made to collect into a focus the light which numerous able observers and theorists have subsequently thrown upon the question. The intricacy of the problem has, indeed, increased almost in proportion to our enlarged knowledge of its conditions; and in spite of the labours of a large and very distinguished body of investigators, not only do many important points remain matters of dispute, but the very materials for a complete solution are still wanting.’
[2] Handbuch der Gletscherkunde, von Dr. Albert Heim, Zürich (Stuttgart: Verlag von J. Engelhorn, 1885, 18 francs.)
CAUSE OF GLACIERS
The joint cause of glaciers is precipitation and cold. A low temperature alone can do nothing without moisture, and this fact quickly disposes of the popular notion that glaciers invariably exist in cold countries. Thibet, for instance, and also some parts of Arctic North America are destitute of ice streams, though eternal cold may be said to reign supreme in these parts.
Imagine for a moment the higher mountains clear of snow and ice, and then watch for the formation of a glacier. Snow falls and fills up all the valleys and gullies, avalanches descend from the higher parts, and a great accumulation gathers in all hollows. By constant repetition of snow-falls (always provided a greater quantity is deposited than can be melted by the sun’s rays and by the natural warmth of the earth’s crust) great pressure is put upon the lower portions by the superincumbent accumulation, and aided by the infiltration of water and refreezing (or ‘regelation’ as the correct term is), a large body of ice is formed which at once begins to move down the valleys containing it.