THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



SEPTEMBER 1862. 



XXIII. On the Conformation of the Alps. 

 By Professor Tyndall, KR.S* 



DURING the last seven summers I have had opportunities of 

 viewing the Alps from many commanding points of view, 

 and while in such positions have often speculated on the agen- 

 cies which have given this portion of the earth's surface its re- 

 markable conformation. How have the hills risen, or how have 

 the valleys sunk ? I think the mere inspection of the mountains 

 from a sufficient elevation must suggest insuperable difficulties 

 to the assumption that the present mountains have arisen through 

 the action of forces localized beneath their bases, or that the 

 valleys, as they now exist, can have sunk through want of local 

 support underneath. Probably nobody entertains such a notion. 

 Upheaval may have occurred, and sinking may have occurred; but 

 it is next to inconceivable that either action should have been 

 so parcelled out as to produce the present conformation of the 

 Alps. A general elevation of the land must be assumed, pro- 

 ducing a kind of lopsidedness as regards the figure of the earth ; 

 and the question then occurs, how has the land thus elevated 

 been carved into its present form. * 



In the uplifting of the land, cracks and fissures would probably 

 be produced, and the valleys might be regarded as the traces of 

 these cracks and fissures — widened and deepened, it may be, by 

 subsequent denudation. But the direction of the valleys is not 

 that in which cracks would take place. The valleys generally 

 follow the line of steepest fall, and this would be the line of greatest 

 tension on the lifting of the mass ; consequently the mechanical 

 conditions of the problem would lead us to infer cracks at right 

 angles to the present valleys instead of along them. Take, for 



* Communicated bv the Author. 

 Phil. Mag. S. 4. Vol. 24, No. 160. Sept. 1862, N 



