Natural Historv. 57 



as the permanence of Ocean basins and the fixedness of Con- 

 tinental outhnes. 



Now the soHd surface-deposits of our globe are known to 

 be a delicately sensitive skin which can vibrate to the load of 

 a passing- cart, or be thrown into far travelling waves of 

 vibration by every earth-tremor and volcanic disturbance, in 

 Valparaiso or Japan, in Sumatra or the Carribean Sea : all 

 of which are now recorded daily in the Isle of Wight Obser- 

 vatory. 



Moreover, there seems to be no eternal fixedness in the 

 outlines of Ocean basins. Suess and other good authorities 

 believe in great secular oscillations of the Continents by which 

 huge landmasses in the Mediterranean, in the Gulf of Mexico, 

 off Patagonia, and elsewhere, are alternately raised above 

 the sea or plunged deep below the waters of the Ocean. 



Yet these movements are not exactly regular. The creep 

 of the Earth must be considerecl As our planet revolves the 

 outstanding ridges of the Earth's crust, especially those 

 mountain ranges which run North and South, must in the 

 course of ages, gradually shift in direction, leading to great 

 transgressions of the Sea and the drowning of the Western 

 flanks of the Continents.* 



This instability seems to be especially remarkable in the 

 case of Antarctica. Sometimes it emerges and we seem to 

 see, with Mr Hedley, visions of rippling brooks, of singing 

 birds, of blossoming flowers, and of forest glades. Then it 

 retires in a paroxysm of diastrophic energy beneath ice- 

 sheets, and becomes a desolation scarcely able to support even 

 for a few months either the Scotch or the Scandina\ian 

 explorer. 



But the idea that Tertiary Antarctica was a sort of 

 clearing-house for the migrations of Araucaria, Iguanas, 

 Acanthodrilids, Buprestidae, and other animals and plants, 

 seems to be fairly well established. Although I still feel that 

 it is dangerous to summon Continents or land-bridges from 



* Schwarz, (leog. Jour., Sept., 1912. 



