M. Agassiz on Glaciers, Moraines, and Erratic Blocks. 373 



they must generally have been rounded and smaller, and there 

 must also have been immense moraines reposing on the Jura, 

 which, however, have no existence.* 



The prevailing opinion attributes the transport of these 

 blocks to vast currents of water, or to floating ice. 



The greatest difficulties which exist in this theory, and we shall 

 mention but a few of them, are first to give a sufficient expla- 

 nation of the origin of these currents, and of the rapidity it is 

 necessary to assign them, in order that they might be able to 

 transport such enormous masses; if, at the same time, it be admit- 

 ted, as every thing seems to indicate, that they have been trans- 

 ported qfler the elevation of the Alps. For in this case these cur- 

 rents must have started from the crests which separate the valleys, 

 because the phenomenon of the blocks presents itself in all the 

 Alpine valleys, and on both slopes of the chain ; that is to say, 

 to meet the exigencies of the case they must have been projected 

 from all these crestsf with an impetuosity which would not 

 permit the blocks to fall below the level in which they are found 

 in the Jura and the Alpine valleys where now there are no gla- 

 ciers, for even the existence of the great moraines is denied, in 

 order that the deposition of their blocks may be attributed to 

 the same streams. But how is it possible that currents of wa- 

 ter of several leagues in length (I here speak of the lateral \v\- 

 leys which debouch into the principal ones) could have con- 



" I have no intention of describing the distribution of the erratic blocks 

 which occur on the slopes of the Jura, inasmuch as they are generally known 

 since the publication of the researches of Messrs Leop. de Buch, of Escher de 

 la Linth, and of De Luc on the subject. I shall only remark, that their ac- 

 cumulation in different places does not at all agree with the theories which 

 have been proposed to explain their transport. Thus the greatest accumu- 

 lations, so far as I know, are found at an inconsiderable distance from each 

 other, near the summit of Mont Auber, and at the bottom of Noiraigue, 

 which are at very different levels, and are not in an ascending line whose 

 summit would be Chasseron. On the contrary, upon the border of the se- 

 veral steeps of the Jura they are most markedly seen, and more particularly 

 on the line which the depression of the upper beds of the Portland Rock pro- 

 duces along the whole length of the Neuchatel .Jura, between the Castle of 

 Neuveville, Fontaine-Andr^, Pierre-k-Bot, Troirod, Chatillon, Fresens, Mu- 

 truz, &c. 



t Any system of banking up or of breaking up, which can be imagined, 

 will never explain so many facts common to so many valleys. 



