4 Proceedings of the Roiial Irish Academji. 



More recently, in a series of interesting articles, Professor Hull lays stress 

 on the occurrence of channels in these platforms, and urges that they repre- 

 sent the drowned river-valleys and cations of an ancient land-surface. By 

 means of the Admiralty charts he succeeded in tracing the course of the 

 Eiver Shannon for a hundred miles beyond its present mouth, right to the 

 edge of the continental platform, while he followed the continuation of the 

 Eiver Erne for a distance of eighty miles from the Irish coast.' 



In America similar researches have been conducted, chiefly by Dr. Spencer.= 

 He maintains that the drowned channel of the Hudson Eiver is clearly 

 traceable across the submarine shelf of the continent for over a hundred 

 miles, but that the exact course of the ancient Laurentian valley cannot be 

 located with certainty. These submarine valleys, he thinks, were sculptured 

 on the great continental slopes by atmospheric agents, and these features are 

 considered by him to be more recent, in point of age, than the remnants of 

 the Miocene accumidations of the coastal plains. 



Professor Hull advocates an elevation of the land during the early part of 

 the Glacial period of 7000 to 8000 feet. Dr. Spencer even suggests an ujilift 

 of 12,000 to 15,000 feet. 



A more cautious attitude on these oceanographic problems is adopted by 

 Mr. Huddleston. He concedes tliat some sort of a bridge across the Atlantic 

 may have exi.stc<l during portions of tlie Tertiary era; Iml, he does not 

 believe in an uplift lieyond 2000 or 3000 feet.^ 



The subject of continental shelves has lately received renewed attention 

 from Dr. Nansen, and is discussed Viy him at great length. At several places, 

 lie argues, there is weighty evidence for the sujiposition Ihat the drowned 

 river-valleys have been sculptured after the formation of the continental 

 shelves. The latter consequently have been dry land after their formation.* 



When the basaltic plateau so graphically described by Sir Archibald 

 Geikie towered about 1500 feet above sea-level, the Faroes and Iceland, 

 according to Dr. Nansen, were probably connected with one another by land 

 (p. 173). He believes the continental shelf of Iceland to have been formed 

 chiefly in Pre-Glacial times during the Pliocene and Pleistocene periods 

 (p. 172). 



Dr. Thoroddsen's ideas are similar, in so far as he strongly repudiates the 

 suggestion of a Post-Glacial land-connexion.' 



' Hull, E., " Submerged Terraces and River Valleys. " 



' Spencer, J. W., " Submarine Valleys," p. 224. 



' HudiUcston, W. H., " Eaatcrn Margin of Norlh Atlantic Basin," p. 148. 



' Nansen, F., " Xorth Polar Expedition," p. 192. 



' Dr. Stejneger very kindly directed my attention to this paper. 



