Permanence of Continents 301 
His position still remains inexpugnable that it is not permissible to 
invoke geographical change to explain difficulties in distribution 
without valid geological and physical support. Writing to Mellard 
Reade, who in 1878 had said, “While believing that the ocean-depths 
are of enormous age, it is impossible to reject other evidences that 
they have once been land,” he pointed out “the statement from the 
Challenger that all sediment is deposited within one or two hundred 
miles from the shores.” The following year Sir Archibald Geikie? 
informed the Royal Geographical Society that “No part of the 
results obtained by the Challenger expedition has a profounder 
interest for geologists and geographers than the proof which they 
furnish that the floor of the ocean basins has no real analogy among 
the sedimentary formations which form most of the framework of the 
land.” 
Nor has Darwin’s earlier argument ever been upset. “The fact 
which I pointed out many years ago, that all oceanic islands are 
volcanic (except St Paul’s, and now that is viewed by some as the 
nucleus of an ancient volcano), seem to me a strong argument that 
no continent ever occupied the great oceans?,” 
Dr Guppy, who devoted several years to geological and botanical 
investigations in the Pacific, found himself forced to similar con- 
clusions. “It may be at once observed,” he says, “that my belief in 
the general principle that islands have always been islands has not 
been shaken,” and he entirely rejects “the hypothesis of a Pacific 
continent.” He comes back, in full view of the problems on the 
spot, to the position from which, as has been seen, Darwin started : 
“Tf the distribution of a particular group of plants or animals does 
not seem to accord with the present arrangement of the land, it is 
by far the safest plan, even after exhausting all likely modes of 
explanation, not to invoke the intervention of geographical changes; 
and I scarcely think that our knowledge of any one group of organ- 
isms is ever sufficiently precise to justify a recourse to hypothetical 
alterations in the present relations of land and sea‘.” Wallace 
clinches the matter when he finds “almost the whole of the vast 
areas of the Atlantic, Pacific, Indian, and Southern Oceans, without 
a solitary relic of the great islands or continents supposed to have 
sunk beneath their waves®.” 
Writing to Wallace (1876), Darwin warmly approves the former’s 
“protest against sinking imaginary continents in a quite reckless 
1 More Letters, 11. p. 146. 
2 « Geographical Evolution,” Proc. R. Geogr. Soc. 1879, p. 427. 
3 More Letters, 1. p. 146. 
‘ Observations of a Naturalist in the Pacific between 1896 and 1899, London, 1903, 
1. p. 380. 
5 Island Life, p. 105. 
