I 



M. Agassi z 071 Glaciers, Moraines, and Erratic Blodis. 379 



consequence of the continual movements which the ice expe- 

 riences, in alternately melting and congealing at the differ- 

 ent hours of the day and seasons of the year. These effects 

 ought to be described in detail ; but as they are partly known 

 I shall not dwell upon them .* I shall only remark, that the 

 power of the action, so far as the ice is concerned, is immense ; 

 for these masses, continually moving upon each other, and on 

 the surface, bruise and grind down every thing moveable, and 

 polish the solid surfaces on which they repose ; at the same 

 time that they push before them all that they encounter, with a 

 force which is irresistible. It is to these movements we must 

 attribute the strange superposition of rolled pebbles, and of 

 sand which immediately repose upon the polished surfaces ; 

 and it is unquestionably to the grating of this sand upon these 

 surfaces that the fine lines which we find are owing,^and which 

 would never have existed if the sands had been acted upon by 

 a current of water : for neither our torrents, nor the stormy 

 waters of our lakes, produce any thing like this upon the very 

 same rocks. As to the longitudinal direction of these fine lines, 

 and of the furrows which are observed upon the polished sur- 

 faces, it ought to be observed that they must have resulted from 

 the much gi-eater facility which the ice had in dilating itself in 

 the direction of the great^ Swiss valley, than transversely, con- 

 fined as it was between the Jura and the Alps ; the phenomenon 

 itself commencing only with the retreat of the ice, at the time 

 that the Alps appeared. I have not the slightest doubt that the 

 greater number of the phenomena which have been attributed 

 to vast diluvial currents, and in particular those which M. 

 Seefstrom has recently made known, have been produced by 

 ice. 



Upon the elevation of the Alps, the surface of the earth 

 would be reheated, and the caloric disengaged on every side 

 would produce the melting of the ice, which would gradually 

 retire into its present domain. Clefts would first be formed in 

 those places where the ice was thinnest, that is to say, on the 

 summits of the mountains and the hills which were covered by 



" M. Scbimper has written a most inlereiting work upon the cflfbctsof ice, 

 to which I bliould have been most liappy to refer if it had been published. 



