A Period in the History of our Flmet. 21 



into compact ice was impossible, it follows that there could be 

 no moving of ice-fields in any direction during that period ; and 

 I must lay great stress upon this point, because it presents an 

 essential difference betwixt my views and those of various 

 other men of science, who likewise seek to explain the trans- 

 port of erratic blocks by masses of ice, but in an anomalous 

 manner. During the glacial period there was no motion ; not 

 a brook, not a rill furrowed the surface of the snowy cover- 

 ing, to remind by its purling that all life had not yet become 

 torpid. Scarce could the sun, formerly so quickening, soften 

 the surface of the snow by his most powerful rays ; water, so 

 far as the ice-covering extended, existed only in a frozen state. 

 But according to our present state of knowledge, there can be no 

 such thing as motion of the glacier ice, until the warmth of 

 the surrounding media has become such as to cause the melt- 

 ing of the superficial strata. Just as it is only under its ex- 

 citing influences that life in general can exist, and as without 

 its beneficent operation life must cease, so the only life which 

 the glacier exhibits, the single phenomenon by which it seems 

 to take part in the general life of nature — motion, demands 

 warmth as the medium and condition of its existence. It was 

 not, therefore, until the time when a return of warmth, from 

 whatever source it may have come, smiled upon the torpid 

 globe — when the sun began to exercise its powerful influence 

 with renovated force — when under its warmer beams the crust 

 began to dissolve, the ice to soften — it was not until then that 

 all these grand phenomena could take place, of which the sur- 

 face of our present earth is the witness. What, therefore, 

 the majority of geologists liarve hitherto believed to be the re- 

 sult of immense floods and currents, and a few to have been 

 caused by the increase and the progressive motion of glaciers, 

 namely, the transportation of erratic blocks, of alluvial boul- 

 ders, and the polishing and channelling of rocks — these are 

 to me manifestations of the retreat of the glacial period, phe- 

 nomena which denote the moment when an alteration in the 

 climate of our earth began to confine the cold within those 

 narrow boundaries which it now occupies — phenomena which 

 denote the places whence torpid winter began her slow retreat 



