66 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 30, 



regulate their movement. Sir Roderick conceiyes, that the physical 

 phsenomena of the Alps and Jura compel the geologist to restrict the 

 former extension of the Alpine glaciers within infinitely less bounds 

 than have been assigned to them by those authors. 



True old glacier moraines may, he thinks, be always distin- 

 guished, on the one hand, from the ancient allmda, and on the 

 other from tumultuous accumulations of gravel, boulders and far- 

 transported erratic blocks, as well as from all other subsequent detritus 

 resulting from various causes which have affected the surface. He 

 first shows, from the remnants of the old water-worn alluvia which 

 rise to considerable heights on the sides of the valleys, that in the 

 earliest period of the formation of the Alpine glaciers, water, whether 

 salt, brackish or fresh, entered far into the recesses of these moun- 

 tains, which were then at a considerably lower level, ^. e. not less, per- 

 haps, than 2500 or 3000 feet below their present altitude. 



He next appeals to the existing evidences in the range of Mont 

 Blanc to show, that as each glacier is formed in a transverse upper 

 depression, and is separated from its icy neighbour by an intervening 

 ridge, so by their movement such separate glaciers have always pro- 

 truded their moraines across the adjacent longitudinal valleys into 

 which they descended — and never united to form one grand stream of 

 ice in the valley below. To prove this, it is affirmed that there are 

 no traces of lateral moraines on the sides of the adjacent main valleys, 

 whether on the side of the great ridge from whence the separate 

 glaciers issued or on the opposite side of such main valley, which 

 must have been the case if a large mass of glacier ice had ever de- 

 scended it. On the contrary, examples of the transport of moraines 

 and blocks across such main or longitudinal depressions are cited 

 from the valley of Chamonix on the one flank and from the AUe'e 

 Blanche and Val Ferret on the other or south side of the chain of Mont 

 Blanc. Another proof is seen in the ancient moraine of the Glacier 

 Neuva, the uppermost of the valley of the Drance ; and a still stronger 

 case is the great chaotic pile of protogine blocks accumulated on the 

 Plan y Boeuf, 5800 French feet above the sea, which have evidently 

 been translated right across the present deep valley of the Drance, 

 from the opposite lofty glacier of Salenon. 



Ha\ing thus shown that not even the upper longitudinal and flank- 

 ing valleys around Mont Blanc were ever filled with general ice- 

 streams, the author has no difficulty in demonstrating that all the 

 great trunk or lower valleys of the xlrve, the Done, and the Rhone, 

 offer no vestiges of what he calls a true moraine ; since although they 

 contain occasional large erratic blocks, for the most part irregularly 

 dispersed, all the other detritus is more or less water-worn, to great 

 heights above their present bottoms. As Venetz and Charpentier 

 have attached great importance to the original suggestion of an old 

 peasant of the Upper Vallais, that a great former glacier alone could 

 have carried the erratic blocks to the sides of the lower valley of the 

 Rhone, so on the other hand the author, if he had had any doubt 

 himself, would have rehed on the practised eye of his intelligent 

 Chamonix guide Auguste Balmat, who never recognized the remains 



