ON THK CAUSE OF GLACIER MOTION. 413 



old and new world, tave now been satisfactorily explained. That the 

 scratches and groovings referred to have been, and, indeed, only could 

 have been caused by the action of rocks and stones imbedded in ice 

 and forced over the surface of the earth, seems to have been admitted 

 by all; but, how such immense masses of ice, extending over superficies 

 of many square miles, should have been so impelled, has, I believe, 

 hitherto been considered a mystery ; at least, so far as I know, no cause 

 adequate for such tremendous results has been suggested. 



It may be considered presumptuous in one unknown to science, to 

 venture to offer a solution of a mystery that has, till now, eluded the 

 attempts of the scientific word; but I believe it to be better to try and 

 do good, even with the certainty of failing, than to sit down in apathy 

 without making the attempt. 



It is a well known fact that all glaciers have an onward, or progressive 

 motion. The immense heaps of rocks, stones, mud, &e. (moraines), 

 which mark the limits of glaciers, prove this beyond a doubt; as do 

 also the differences between the summer and winter limits of the same 

 glaciers. This motion is invariably in a direction from its source in the 

 mountain to its extremity in the valley (for it is necessary to the forma- 

 tion of a river of ice that it should be confined at each side, as its lateral 

 expansion would deprive it of its distinctive character: a valley, there- 

 fore, is an indispensable condition of a glacier), irrespective altogether 

 of the inclii3ation of the bottom of the valley; thus disproving the 

 gravitation theory of Prof. Forbes, of Edinburgh, which for some time 

 obtained favor among geologists, though, in my opinion, the theory of 

 Prof. Agassiz, of Switzerland, was, albeit short of the truth, neverthe- 

 less, a much nearer approach to it. He imagined that the glacier being 

 full of chinks, owing to its being composed of snow and ice, and on its 

 being exposed to the action of the rays of the sun portions of the ice 

 were melted, the water flowed into these chinks ; and thus, by the 

 alternate thawing and freezing of the water so lodged, the movement of 

 the whole mass was effected. Surely never was the solution of a great 

 scientific difficulty so .nearly attained : another step, and it had been 

 solved. It seems to me that the great defect in the learned Professor's 

 reasoning lies in this, that the progressive motion is ascribed to the 

 alternate thawing and freezing of the water in the cavities in the glacier, 

 and the consequent contraction and dilatation of the water, and, by 

 that much only, of the volume of the glacier ! Now, if this were true, 

 absolutely, it would apply with equal force to the glacier throughout its 



