BY CAPTAIN F. W. BUTTON. 47 



of continental and oceanic areas negatives it. This doctrine — 

 which is not accepted by all geologists* — is founded on the 

 undoubted fact that the principal mountain ranges in the northern 

 hemisphere, and, perhaps, in Australia also, are formed of shallow 

 water sediments representing all periods from the Silurian upwards; 

 consequently land must have existed in their neighbourhood all 

 that time; and from this it is inferred that the present oceanic 

 areas have always been sea. The proof, however, is far from 

 being complete, and no explanation has, as yet, been given either 

 (1) of the remarkable submarine plateaux found in the basins of 

 the S. Pacific and S. Atlantic Oceans; or (2) of the sudden 

 irruption of mollusca, bony-fishes and dicotj'ledons into N". 

 America during the close of the Cretaceous period, followed by a 

 host of Eutherian mammalia in the Eocene; or (3) of the place 

 of origin of the peculiar S. American mammalia. The former 

 existence of a Mesozoic Pacific continent seems to me, as it did 

 to Professor Huxley, the simplest explanation of all these 

 difficulties; we can never expect to attain certainty in the matter, 

 but I think that the weight of the evidence is in its favour. 



* Gardner, Geol. Mag. 1882, p. 546 ; Hutton, N.Z. Journal of Science, 

 Vol. I. p. 406 (1883) ; Blandford, Q.J.G.S. XLVI. Proceedings, p. 59 (1890); 

 Oldham, Geol. of India, 2nd Ed. p. 211 (1893). 



