122 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 5, 



would give an extension of the glaciers sufficient to account for all 

 the moraines and polished and striated rocks in Switzerland. After 

 tracing the upward progress of the Alps during their rise of 9000 

 feet from their position at the first observed water-level to their 

 present heights, it requires but a slight stretch of the imagination to 

 suppose a farther elevation of 1500 or 2000 feet to account for the 

 earlier glaciers, followed by a subsequent sinking of the land to its 

 present level. But so many other causes may have produced a 

 change of climate, and the proofs of a glacial period in other coun- 

 tries are so numerous, that it seems better to look for a general 

 cause of a colder climate throughout Europe at the period in question, 

 than to limit our views to a local movement peculiar to the Alps. 



Erratic Blocks. — The subjects of this paper approach too nearly 

 to the much-debated question of Erratic Blocks for me to leave them 

 entirely unmentioned. A large proportion of the rounded boulders 

 and gravel may have been distributed over the Lowlands of Switzer- 

 land during the elevation of the Alps ; for, as this elevation went 

 forward, every portion of the country must in its turn have been part 

 of the coast, and consequently acted on by the waves. This may 

 account for the distribution of the smaller rounded blocks at all the 

 lower levels. 



But, if that explanation be admitted for the rounded erratics, we 

 have still to account for the great accumulations of large blocks, often 

 angul'ir, which lie scattered here and there throughout Switzerland 

 above the deposits of gravel, and the presence of which on the Jura 

 and on the sides of the hills that enclose the valley of the Rhone has 

 led to so much discussion. On the Jura these blocks reach, accord- 

 ing to M. Charpentier, to the height of 4250 feet above the sea*. 

 The blocks of Monthey, so eloquently described by Prof. J. Forbes, 

 are stated to be at least 500 feet above the plain t, or above 1 700 

 feet above the sea. 



It will be seen by Table III. that the sea has stood for some time 

 round the Alps near each of these levels ; thus we have the existence 

 of a sea demonstrated, on which ice-rafts carrying such blocks may 

 have floated : and it only requires a climate capable of producing 

 floating ice, to furnish an agent for transporting blocks of any size, of 

 stranding them in lines along the coast, or dropping them here and 

 there at the bottom of the sea^. The extension of the glaciers, 

 caused probably by a climate colder than the present, followed soon 

 after the period when the sea stood at the heights mentioned, and 

 thus the conjectural explanations of the two succeeding phsenomena, 

 referring both to a colder climate, harmonize together, and save us 

 from the necessity of the gratuitous creations of a " Glacier of the 

 Rhone " ending on the side of the Jura nearly 3000 feet above the 



* If, as it is probable, these are French feet, they are equal to 4528 English 

 feet ; if Swiss feet are intended, they are equal to 4182 English feet. Not having 

 Charpentier's work at hand, I quote from the abstract of it in Edinb. New Phil. 

 Journ. vol. xxxiii. 



t * Travels in the Alps,' p. 51. 



t See Sir C. Lyell's account of the transport of blocks by the breaking up of 

 coast-ice now going on in the Bay of Fundy. 



