THE 



aEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE II. VOL. VIM. 



No. VI.— JUNE, 1881. 



OI^IC3-IDiT^^L -A.I^'X'IGIilEIS. 



I. — Subsidence and Elevation, and on the Pekmanence of Oceans. 



By J. Starkie Gaedner, F.G.S. 

 rflHE theory of permanent Continents and Oceanic basins, opposed 

 I as it is to the general teaching of text-books, seems to have 

 given rise to comparatively little discussion. In the latest edition, 

 for instance, of Lyell's Principles, we read : " It is not too much 

 to say that every spot which is now dry land has been sea at some 

 former period, and every part of the space now covered by the 

 deepest ocean has been land." The new theory has been upheld 

 chiefly by Sir Wyville Thomson, Prof Geikie and Mr. Wallace. 

 The latter especially has collected every kind of evidence together 

 that seems to support it in his latest, and most admirable work, 

 " Island Life." By a process of reasoning, supported by a large 

 array of facts of diiferent kinds, he arrives at the conclusion that 

 the distribution of life upon the land, as we now see it, has been 

 accomplished without the aid of important changes in the relative 

 positions of continents and seas. Yet if we accept his views, we 

 must believe that Asia and Africa, Madagascar and Africa, New 

 Zealand and Australia, Europe and America, have been united at some 

 period not remote geologically, and that seas to the depth of 1000 

 fathoms have been bridged over ; but we must treat as " utterly 

 gratuitous, and entirely opposed to all the evidences at our command," 

 the supposition that temperate Europe and temperate America, 

 Australia and South America, have ever been connected, except by 

 way of the Arctic or Antarctic Circles, and that — lands now separated 

 by seas of more than 1000 fathoms depth have ever been united. 



Mr. Wallace, it must be admitted, has succeeded in explaining 

 the chief features of existing life distribution, without bridging 

 the Atlantic or the Pacific, except towards the Poles, yet I cannot 

 help thinking that some of the facts might perhaps be more 

 easily explained by admitting the former existence of the connexion 

 between the coast of Chili and Polynesia and Great Britain and 

 Florida, shadowed by the sub-marine banks which stretch between 

 them. Nothing is urged that renders these more direct connexions 

 impossible, and no physical reason is advanced why the floor of 

 the Ocean should not be upheaved from any depth. The route by 

 which the floras of South America and Australia are supposed 

 to have mingled is beset by almost insurmountable obstacles, and 

 the apparently sudden arrival of a number of sub-tropical Amei'ican 

 plants in our Eocenes, necessitates a connexion more to the south 



DECADE II. — VOL. VIII. — NO. VI, 16 



