82 Mr. J. Ball on the Formation of 



common alike to physics and to geology ; their solution depends 

 in a great part upon facts which must be studied on the ground ; 

 and I am thus led to hope that a somewhat long and extensive 

 acquaintance with the Alps, during which the questions at issue 

 have been very frequently the subject of my thoughts, may 

 authorize me without presumption to take a share in the discus- 

 sion. "Writing at a distance from England, and with but slight 

 opportunities for knowing what is passing elsewhere, I shall be 

 forgiven if I repeat objections previously urged by others, or 

 advance arguments that have been already satisfactorily answered. 



Professor Ramsay attributes to the action of glacier- ice the 

 hollowing out of lake-basins in the Alps and elsewhere; Pro- 

 fessor Tyndall sees in the same powerful agent the main, if not 

 the exclusive, means for the formation of alpine valleys. An 

 anonymous writer, in terms which show that his knowledge of 

 the subject is on a par with his good taste, has confounded 

 together the scope of the two papers. I hope to show not only 

 that the problems attempted to be solved by their writers are 

 different, but, furthermore, that the main objections to each 

 solution rest upon considerations entirely distinct. 



Taking, in the first instance, the larger of the two questions 

 raised for discussion, I shall inquire whether there is reason to 

 admit Professor TyndalPs conclusion, drawn chiefly from his 

 observations in the neighbourhood of Monte Rosa, that the 

 valleys of the Alps have, as a general rule, been scooped out by 

 great glaciers from the flanks of previously continuous mountain 

 masses. 



The first thought of any one considering this question is to 

 endeavour to take a comprehensive view of the present configu- 

 ration of the surface. If the reader will look at any general map 

 of the Swiss and Savoy Alps, he will in the first place observe 

 that between the higher central ranges and the plains of France 

 there is interposed a zone of secondary rocks, elevated into ridges 

 from 4000 to 6000 feet above the sea-level. In carrying his eye 

 along this zone from the neighbourhood of Grenoble to that of 

 Aarau, he will see that the direction of the ridges, which is at 

 first nearly north and south, is gradually bent towards the east, 

 so that the principal chain of the Jura points from N.E. by E. 

 to S.W. by W. He will further observe that the chain nowhere 

 consists of a single ridge, but of three, four, or five parallel 

 ridges with furrow-like valleys lying between them, here and 

 there cut through by some stream that appears to flow through 

 a fracture that has traversed the entire range. Including along 

 with the Jura the ranges of Western Dauphine, the Vosges 

 Mountains, and the somewhat higher ridges west of the valley 

 of the Arty, it will be apparent that the arguments of Professor 



