"Wynne — Presidential Address. 299 



if lie works them out in more detail an important step may be 

 gained towards the solution of this interesting question. 



If we follow our American colleagues, Messrs. Powell and 

 Gilbert, in assuming that " all large mountains are new moun- 

 tains," taking for example the Alps and Himalayas as being 

 mainly formed in the Tertiary period, having now such structural 

 examples before us as the Highlands present, we can hardly press 

 this generalization to the conclusion that, were it possible to 

 examine the central skeletons of these ranges, there would not be 

 disclosed a recurrence of consecutive stages of disturbance and 

 regional metamorphism of similar kinds, showing perhaps a direct 

 relationship between lateral displacement and the depth at which 

 it occurred, influenced by the amount of the then overlying 

 materials, and varying, it might be, in intensity or form, when 

 the overlying load was greater or less. 



Admitting the rashness of venturing amongst obscure possibi- 

 lities or questionable theories, yet, for the moment, supposing with 

 the majority, that the earth's crust overlies a viscous substratum 

 enclosing' a solid nucleus, and that consequently mobility of the 

 outer envelope may be conceded where, from any cause an impetus 

 can be found, the result would be those combinations of tangential 

 and vertical (or gravitation) pressure which are generally regarded 

 as having accompanied the forcing of all folded strata into 

 narrower lateral limits. If this be so, it does not seem unreason- 

 able to imagine that the dragging of one deep-lying portion of the 

 crust beneath or over another might become but a question of the 

 cohesion or weakness of parts of the crust itself. The earliest 

 theories of the spheroidal formation of the earth have been con- 

 nected w T ith its rotation, and if this connexion can be extended to 

 such dragging movement, it would be further interesting to note 

 the latitudinal direction of the Scotch displacements to the west- 

 ward — a direction that, in the absence of actual proof, might vary 

 towards the east or west, according to whichever of the contiguous 

 displaced masses was regarded as that which moved the most. 



We can realize the descriptions of the striking natural features 

 observed with much greater facility than we can imagine their causes, 

 let these be what they may, and as our knowledge stands it is wisest 

 not to indulge in dogmatic assertions. At any rate, to discuss such 

 matters further here would be to recklessly invade -regions of pro- 



