Wynne — Presidential Address. 



297 



sequence of the pressure remaining regionally inactive as to the 

 production of motion. The metamorphism here suggested would 

 be commensurate with the magnitude of the pressure and the 

 amount of movement which obtained. 



From the considerations the following series of alterations in 

 the crust might be deduced : — 



1st. A state of quiescence or equilibrium followed by the 

 formation of a dome or bulge, resulting, say, from contraction, 

 and consequent relief from vertical pressure. 



Fig. 1. 



Initiatory stage, dome, or bulge in the crust, relieving vertical pressure at A, remaining 



active at B, B. 



2nd. An accumulation of crumpled and not necessarily meta- 

 morphosed strata towards the region of disturbance, with increas- 

 ing elevation of the bulged crust, accompanied by denudation, and 

 deposition of the material in the subsiding areas; By the motion 

 thus originated, regional metamorphism would be initiated, and 

 would continue until the pressures were equalized in the affected 

 regions — until, in fact, cosmical equilibrium was restored. 



Fig. 2. 



Further stage. A, dome or bulge denuded, the materials being deposited on the flanks. 

 Depression and attenuation result in metamorphism, where the figure is cross- 

 hatched, folding taking place under A. L, original surface. 



3rd. The formation of a new arch or dome over an area of 



