SCRAMBLES AMONGST THE ALPS.

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glaciers themselves, from the abrasion of the rocks overwhich their ice passes, are minute compared with theaccumulations which are furnished from other sources.These great rubbish-heaps are formed, one may say almostentirely, from ddbris which falls, or is washed down theflanks of mountains, or from cliffs bordering glaciers; andare composed, to a very limited extent only, of matter thatis ground, rasped, or filed off by the friction of the ice.

If the contrary view were to be adopted, if it could bemaintained that “ glaciers, by their motion , broke off massesof rock from the sides and bottoms of their valley courses, andcrowd along everything that is movable, so as to form largeaccumulations of debris in front, and along their sides,” *the conclusion could not be resisted, the greater the glacierthe greater should be the moraine.

This doctrine does not find much favour with those whohave personal knowledge of what glaciers do at the presenttime. From De Saussure f downwards it has been pointedout, time after time, that moraines are chiefly formed fromdebris coming from rocks or soil above the ice, not from thebed over which it passes. But amongst the writings ofmodern speculators upon glaciers and glacier action inbygone times, it is not uncommon to find the notionsentertained that moraines represent the amount of excava-tion (such is the term employed) performed by glaciers, orat least are comprised of matter which has been excavatedby glaciers ; that vast moraines have necessarily been pro-duced by vast glaciers ; and that a great extension of glaciers—a glacial period—necessarily causes the production ofvast moraines. It is needless to cite more than one or two

* “Atlas of Physical Geography,” by Augustus Petermann and theRev. T. Milner, M. A., F. R. G.S. The italics are not in the original.

t “ The stones that are found upon the upper extremities of glaciersare of the same nature as the mountains which rise above ; but as theice carries them down into the valleys, they arrive between rocks of atotally different nature from their own.”—De Saussure , § 536.