1865.] SIR R. I. MURCHISON ON GLACIERS. 23 



obstruction of any promontory of hard rock. Further, M. Mar- 

 tins, being well acquainted with Norway, indicated that, just as in 

 that country, the face of each rock in a valley was rounded off, 

 polished, and striated where it had been opposed to the advancing 

 mass of ice, and that its opposite or downward face, over which 

 the ice had cascaded or tumbled, was left in a rough state ; thus 

 exhibiting the worn or " stoss-seite." and lee, or protected side, of 

 the Scandinavian geologists. The subsequent works of M. Gas- 

 taldi on the geology of Piedmont, in 1853 and in 1861, bring 

 within well-defined limits the phenomena of old moraines and an- 

 cient drift, and prove that the debris carried over each gorge and 

 valley has been derived from the rocks which specially encase such 

 depressions. He also clearly demonstrated that in many of these 

 cases the gigantic boulders which are piled together and present 

 the character of a cataclysmal origin, can all be accounted for 

 simply by the power of advancing ancient glaciers. In these works 

 M. Gastaldi very properly distinguishes between the erratic blocks 

 which were evidently parts of old terrestrial moraines, and those 

 which, associated with tertiary strata, are found in deposits with 

 marine shells — the larger erratics in the latter, as in the Superga, 

 having been transported in masses of ice which floated on the 

 then sea. 



Various other Italian authors have occupied themselves with 

 glacial phenomena (particularly Omboni, Villa, Stoppani, Cornalia. 

 Paglia, Parolini, &c.) ; the conclusion at which they have all arrived 

 is, that tliere existed an enormous extension of the moraines sent 

 forth by the ancient Alpine glaciers into the great valley of the Po. 

 Geographers who have not studied the phenomena may Well indeed 

 be surprised when they learn, that the hills to the south of the Lago 

 di Garda, and extending by Pozzolengo and Solferino to Cavriano,* 

 or the very ground where the great battles of the year 1859 were 

 fought (the hill of Solferino being 656 English feet above the sea), 

 are simply great moraines of blocks and gravel, produced by the 

 advance of former glaciers which issued from the southern slopes 

 of the Alps. 



Combining these observations with others of his own on the lake 

 of Annecy, M. Mortiilet suggested in 1862 a new theory, in attri- 

 buting to the descent of the glaciers a great excavating power. 



* See Paglio, ' Sulle Colline del Terreno Erraticoall' estremita mer- 

 idionale del Laga di Garda' (with map). 



