250 On the former changes of the Alps. 



paratively tranquil former period which intermitted with geologi- 

 cal revohitionSj there was a constant exhibition of diurnal agencies 

 similar to those which prevail in the present world. In those 

 older timeSj rain must have fallen as now, — volcanic forces must 

 have been active in scattering ashes far and wide, and in spread- 

 ing them out together with sheets of lava beneath the waters^ 

 gradual movements of oscillation and moderate elevations and 

 depressions must have occurred, — long continued abrasion of the 

 sides of mountains must have produced copious accumulations of 

 * debris' to encroach upon lakes, the overflow or bursting of 

 which may have sterilized whole tracts. 



"All such and many more modifications of the ancient surfa- 

 ces of the globe, including many slight breaks in the long ca- 

 reer, were doubtlessly common to all epochs. But whilst no 

 such operations can be compared with those phenomena of dis- 

 ruption and overturning of mountain masses which have been 

 specially dwelt upon this evening, so also according to my view 

 it is impossible, that any amount of small agencies, if continued 

 for millions of years, could have produced such results. 



^' In thus attempting to shadow out in the space of an hour all 

 the chief formations and transmutations of a chain like the Alps, 

 1 have probably labored to effect what many persons may deem 

 impossible ; but I have thought that some at least of these even- 

 ing discourses should awaken the mind to the larger features of 

 each science, the details of which must be followed out in courses 

 of lectures. I would beg, therefore, those persons who have not 

 studied geology practically, to dwell chiefly on the facts brought 

 forward, and to believe that they are indisputably and clearly 

 proven. They tell us unmistakably how diflferent creations of 

 animal and vegetable life are entombed in these vast monuments 

 of ancient nature, and they reveal to us that each creation of the 

 successive inhabitants of the surface lived during very long peri- 

 ods of time. They announce to us, in emphatic language, how 

 ordinary operations of accumulation were continued tranquilly 

 during very lengthened epochs, and how such tranquillity was 

 broken in upon by great convulsions. 



*• Being thus led to ponder upon the long history of successive 

 races and also upon some of the most wonderful physical revolu- 

 tions the chain has undergone, we cannot avoid arriving at the 

 belief, that, in addition to many other great operations, the dis- 

 ruption which upheaved the middle and younger Tertiary forma- 

 tions from beneath the waters, and threw them up into mountain 

 masses accompanying the production of the first great arctic pe- 

 riod known in the history of the planet, was a change of immeas- 

 urable intensity. That change, in short, by which a period of 

 snow, ice, glaciers, floating icebergs, and the transport of huge 

 erratics far from the sources of their origin^ suddenly followed a 

 genial and Mediterranean clime !" 



