100 Mr. J. Ball on the Formation of 



Switzerland and Savoy lie between W.S.W. and E.N.E., and in 

 the Eastern Alps are directed more accurately from W. to E t> 

 are the aggregate results of the action, whether constant or 

 intermittent, of lateral compression ever since the elevation 

 commenced, a period which probably extends from the origin of 

 the earliest palaeozoic rocks to the present time. Though the 

 conception is fundamentally different from that of local subsi- 

 dence, the effect may sometimes be scarcely distinguishable. 



That the meiocene period was one of immense duration is suf- 

 ficiently proved even to geologists who know the formation only 

 in Switzerland ; and it is equally certain that it was accompanied 

 by considerable disturbance of the surface. I can see no diffi- 

 culty in admitting the probability of the action of forces trans- 

 verse to the main chain of the Alps and the Jura during, and 

 subsequent to, the meiocene period, which would have deepened 

 previously existing depressions on the site of the lakes of Neu- 

 chatel, Bienne, Morat, and the western part of the Lake of 

 Geneva. The eastern part of the latter lake has probably a dif- 

 ferent origin. There is nothing, so far as I know, in the coun- 

 try between Bex and the Triassic rocks of Meillerie to make it 

 unlikely that a lake may have existed there before the meiocene 

 epoch. 



I shall very briefly notice a few of the difficulties which occur 

 to some minds in regard to the main principles which are here 

 very imperfectly developed. It is sometimes objected that the 

 formation of ridges and furrows upon the rigid crust of the 

 earth in the manner here suggested, without corresponding 

 undulations of the more deeply situated portions of the crust, 

 assumed to be viscid from high temperature, implies the forma- 

 tion of hollows and vacant spaces, owing to the want of confor- 

 mity in the flexures of the upper surface with those of the inner 

 mass. Without stopping to discuss the possibility of the occa- 

 sional occurrence of such vacant spaces in certain strata, aided, it 

 may be, by the more rapid cooling of the earth's nucleus which 

 some suppose to have proceeded during preceding geological 

 periods, I reply that the objection rests upon an imperfect idea 

 of the action of force upon the solid materials of the globe. I 

 have no doubt that all rocks possess in some measure that pro- 

 perty which, when highly developed, we call plasticity, under 

 the action of adequate force applied with the requisite slowness. 

 During the process of flexure, as I understand it, a portion of the 

 earth's crust lies, as it were, in a mould, which changes its form, 

 it may be, at the rate of a few yards in a million of years ; and 

 the same quality which permits flexure permits that limited 

 degree of mobility of the parts which suffices to fill up the space 

 that would otherwise be vacated by the flexure. The fact that 



