176 PROFESSOR EDWARD HULL^ M.A., LL.D., F.R.S.^ ON 



5. Indications of the partial submergence of Scotland during tlie Roman 



occupation. Evidence derived from the Roman Wall ( Vallum). 

 Views of Sir Archibald Geikie. Statement of Gildas. 



Part III. Date of Emergence of the Land. 



6. Inferential date ; that the final elevation took place well within the 



Christian Era. 



Part IV. Conclusion. 



Introduction. — Whatever may have been the length of time 

 between the Pliocene Tertiary and the historic periods, — 

 generally included in the term " Post-Tertiary " — it cannot be 

 denied that it included several remarkable oscillations of the 

 land of Western Europe — indeed we might say, of the Atlantic 

 sea-board on both sides. Oscillations which have left their 

 impress upon the physical features of the lands, and in this way 

 have powerfully influenced the social character of the present 

 inhabitants. We begin with the first of these terrestrial move- 

 ments of Post-Pliocene times — namely, that of the first glacial 

 elevation — to which Professor James Geikie has given the 

 generally accepted name of " The Great Ice Age." We here 

 recognise a movement of elevation of land reaching a height 

 of several thousand feet above the present surface of the 

 ocean, during which the Continental platform now covered by 

 the waters of the sea was upraised, its surface abraded, and 

 traversed by channels (or cafions) of the existing rivers, to 

 their outlets on the floor of the abyssal ocean at depths of 

 6,000 to 7,000 feet below the present surface. Having already 

 described in the pages of the Journal of the Institute the 

 position and character of these drowned river channels," I 

 need not further allude to them here, except to reassert my 

 conviction that in the great elevation of the continental lands of 

 Europe and Africa of which these submerged river-valleys are 

 evidence, we have a sufficient cause for that vast extension of 

 extreme arctic conditions shown by the glacial phenomena of a 

 past time in Scandinavia, the Alps, Pyrenees and Atlas 

 mountains, extending far beyond the limits of existing glaciers, 

 as also in the British Isles from which the glaciers have 

 altogether passed away.* 



Succeeding to the epoch of the great Ice Age came that of the 



Interglacial stage," in which the British Isles were depressed 

 beneath the ocean to varying dei)ths, of which the maximum 

 was 1,200 feet in Central England, North Wales, and central 



* Trans. Vict. Inst., vols, xxx, xxxi, and xxxii. 



