462 Notices of Memoirs — British Association — A. Stralian. 



concentrated themselves along a belt of country which present* 

 the phenomena of crusliing on a stupendous scale. We have 

 touched in two cases the flanks of a mountain-rani>e, the Caledonian, 

 which was built and ruined before the Carboniferous period ; the 

 Armorican, which was built after that period, and which, though 

 it has stirred so recently as the late Tertiary period, and so 

 energetically as to initiate the physical features and river-system of 

 the south of England, yet expended the greater part of its energy 

 before the Permian period. Lastly, we have found evidence, in the 

 majority of cases, that the disturbances were but renewals of 

 movement along lines of weakness long before established, and that 

 in several cases there has been further renewal along the same lines- 

 during successive periods later than the one we have considered. 

 With such a history before us, and with the knowledge that 

 mountain-ranges have been built in other parts of the world by the 

 upheaval of strata of almost recent date, we have more cause to 

 wonder that the internal forces have left this quarter of the glob& 

 alone for so long, than reason to believe that they have ceased to 

 exist. Changes of level, however, have taken place in comparatively 

 recent times, and are now in progress. Though almost imperceptibly 

 slow, they serve to remind us that a giant lies sleeping under our 

 feet who has stretched his limbs in the past, and will stretch them 

 again in the future. Nor in view of the fact that the structures- 

 I have described have only been revealed by the denudation of vast 

 masses of strata does it seem unreasonable to suppose that they are 

 deep-seated phenomena. The slow changes of level may be the 

 outward manifestation of more complicated movements being irr 

 progress at a depth. 



It is interesting to speculate on what appearance the globe would 

 have presented had it not been enveloped in an atmosphere and 

 covered for the most part with water. Owing to those circumstances 

 it possesses the power of healing old wounds and burying old scars. 

 In their absence we may suppose that the belts of crushing and 

 buckling would have given rise to ridges growing in size at every 

 renewal of movement, for they would have been neither levelled 

 by denudation nor smoothed over by sedimentation. This globe, 

 we may suppose, would have appeared to the inhabitants of another 

 planet as being encompassed in a network, and we are prompted 

 to ask whether our astronomers can distinguish in any other planet 

 markings that may be attributable to this cause. I must remind 

 you, however, how much more remains to be done than I have been 

 able to touch upon to-day. The map (exhibited) represents one 

 episode only in a long series of events, and a series of such maps 

 would be required to illustrate the first appearance of lines of 

 weakness in the earth's crust, the subsequent renewals of movement 

 along those lines, and the formation of new lines in successive 

 geological periods. With the case thus set out we shall be 

 justified in appealing to the physicists for an explanation of the 

 restlessness of this globe. 



