374 M. Agassiz 07i Glaciers, Moraines, and Erratic Blocks. 



veyed such immense blocks to an elevation of more than a thou- 

 sand feet ? Moreover, the fact that the blocks of the different 

 valleys are not similar, and that they are spread, fan-shaped, to 

 a certain distance round the Alps, excludes the idea of that ex- 

 treme rapidity which has been ascribed to the currents for the 

 simple purpose of explaining this transport, without considering 

 that it must, at the same time, have produced effects, a ti'ace 

 of which is no where to be found. This fact, then, most 

 completely excludes the idea of a grand diluvial current pass- 

 ing over all Switzerland in any direction whatsoever. If, again, 

 it were before the elevation of the Alps it is supposed the phe- 

 nomenon occurred, I ask, how has it happened that the lines 

 of these blocks formed in the Alps have not been dislocated by 

 the uprising ? For in 'this case the continuous and parallel 

 dykes of blocks which may be seen u]pon bothJlanTis of the whole 

 of the Alpine valleys, and which follow them in all their wind- 

 ings, whatever may be their direction and tortuosity, will re- 

 main inexplicable, the water proceeding in a rectilinear course 

 in the different windings of the bed in which it flowed, whilst 

 the ice alone acted with the same energy upon every point of 

 the basins which it filled. 



The objections which may be made to the theory of currents 

 are all applicable, to a certain extent, to the theory advanced by 

 several naturalists of their being conveyed by icebergs. It is 

 no difficult matter to transport, in imagination, upon these float- 

 ing islands great angular blocks even to the Jura ; but the 

 other particulars of this great phenomenon are not thereby 

 better explained than by the help of the currents, were we even 

 to admit with M. Elie de Beaumont that the water which fed 

 them proceeded from the glaciers as the source. 



Another objection of the greatest weight, made by M. Schim- 

 per to this theory is, the present state of the lakes of the great 

 Swis's valley. If the blocks have been carried by the currents 

 from the Alps to the Jura, these currents must naturally have 

 passed over the lakes and the longitudinal and transverse val- 

 leys which occur between the two chains. How then has it 

 happened that these lakes and valleys were not filled up, and 

 how are we to explain the angular escarpments of their margins ? 

 However violent, rapid, and deep, these currents may be sup- 



