342 
DARWINISM 
CHAP. 
and that during the course of known geological time the 
continents and great oceans had again and again changed 
places with each other. Sir Charles Lyell, in the last edition 
of his Principles of Geology (1872), said: “Continents, there¬ 
fore, although permanent for whole geological epochs, shift 
their positions entirely in the course of ages; ” and this may 
be said to have been the orthodox opinion down to the very 
recent period when, by means of deep-sea soundings, the nature 
of the ocean bottom was made known. The first person to 
throw doubt on this view appears to have been the veteran 
American geologist, Professor Dana. In 1849, in the Report 
of Wilke’s Exploring Expedition, he adduced the argument 
against a former continent in the Pacific during the Tertiary 
period, from the absence of all native quadrupeds. In 1856, 
in articles in the American Journal, he discussed the develop¬ 
ment of the American continent, and argued for its general 
permanence ; and in his Manual of Geology in 1863 and later 
editions, the same views were more fully enforced and were 
latterly applied to all continents. Darwin, in his Journal of 
Researches, published in 1845, called attention to the fact that 
all the small islands far from land in the Pacific, Indian, and 
Atlantic Oceans are either of coralline or volcanic formation. 
He excepted, however, the Seychelles and St. Paul’s rocks; 
but the former have since been shown to be no exception, as 
they consist entirely of coral rock ; and although Darwin 
himself spent a few hours on St. Paul’s rocks on his outward 
voyage in the Beagle, and believed he had found some 
portions of them to be of a “ cherty,” and others of a 
“ felspathic ” nature, this also has been shown to be erroneous, 
and the careful examination of the rocks by the Abb6 Renard 
clearly proves them to be wholly of volcanic origin. 1 We 
have, therefore, at the present time, absolutely no exception 
whatever to the remarkable fact that all the oceanic islands of 
the globe are either of volcanic or coral formation ; and there 
is, further, good reason to believe that those of the latter class 
in every case rest upon a volcanic foundation. 
In his Origin of Species, Darwin further showed that no 
true oceanic island had any native mammals or batrachia 
1 See A. Agassiz, Three Cruises of the Blake (Cambridge, Mass., 1888), 
vol. i. p. 127, footnote. 
