GEOLOGY. 179 



in the plateaus and in the bays of the Eozoic and Paleozoic 

 lands. See in this connection the same argument against 

 a change of axis stated in the Record for 1876 (page cii). 



AN ANCIENT ATLANTIC CONTINENT. 



The results of soundings over the bed of the Atlantic have 

 made clear the existence through the middle of the ocean, 

 extending from north to south, of a sunken ridge, often less 

 than 1000 fathoms from the surface, while on either side the 

 water has a depth of from 3000 to more than 3450 fathoms; 

 so that the elevation of the ocean's bottom required to make 

 these depths dry land would bring up between them a moun- 

 tain-range from 9000 to 15,000 feet in height. The higher 

 points of this sunken ridge now form the islands of the 

 Azores St. Paul's, Ascension, and Tristan d'Acunha. This 

 discovery was, in a manner, anticipated in 1860 by linger, 

 who, from his studies of the Tertiary flora of Europe and 

 America, was led to imagine a land connecting the two re- 

 gions, over which the plants of North America had passed 

 eastward. This, he supposed, might be the vanished Atlan- 

 tis of which Plato has preserved the tradition. 



Other reasons have led geological observers to conclude 

 that great areas of land existed in the Atlantic region in 

 Paleozoic time; and the present writer, in 1872, urged the ex- 

 istence of a Paleozoic Atlantis, from the ruins of which had 

 been derived the enormous volumes of material which make 

 up the uncrystalline rocks of Eastern North America. The 

 Paleozoic sediments of these regions, many miles in thickness, 

 must, as Hall and H. D. Rogers long since pointed out, have 

 been derived from the waste of great areas of elevated land 

 lying to the eastward. Clarence King lias recently brought 

 forward this doctrine in a forcible manner, and lias described 

 Palse-Atlantis as a land-area of continental magnitude, from 

 which vast quantities of sediment were brought down by 

 rivers and poured into the Palpe-American ocean, upon the 

 subsiding bottom of which were built up the thick Paleozoic 

 formations which stretch throughout Eastern North America. 

 He also claims the existence of a corresponding Pacific con- 

 tinental area, Avhich he names PalaB-Pacifis. The lower Pa- 

 leozoic rocks of Great Britain, when compared with those of 

 Scandinavia and Russia, show a diminution in thickness in 



