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THE 
GEOLOGICAL MAGAZINE. 
Nee) SERieo.:  DEGADE® Th VOL. VIl; 
No. IX—SEPTEMBER, 1880. 
ORTIGINAT ABRTICIAHS. 
—_—__ 
I.—OcrEANS AND CONTINENTS. 
By T. Metuarp Reape, C.E., F.G.S., ete. 
N opposition to the views enunciated by Lyell and the older 
geologists, and until now generally accepted by those who have 
made physical geology a study, an opinion is gaining ground that 
“generally speaking the great continents and great ocean basins 
have occupied their present positions through all geological time ;” 
that they are, though subject to oscillations of level, permanent 
depressions and elevations produced by the gradual diminution of 
the earth’s diameter through loss of heat and consequent sinking in 
of the rigid crust. 
So far as I can learn, Dana appears to have originated the idea 
that the continents have been built up around portions of the crust 
of the earth that have first hardened—a sort of process of evolution ; 
but whether he accepts the rigid position that the sites of the great 
continents and oceans are, within certain limits, unalterable, is not so 
clear. Mr. A. R. Wallace is the great champion of this latter idea, 
though his explanation of the mutations of the position of land and 
sea, as explained in his “ Geographical Distribution of Animals,” and 
incidentally in “ Australasia,” and other writings, seems to overstep 
the bounds of his theory. Mr. Murray, of the Challenger, seems also 
during his voyage to have been deeply impressed with the per- 
manence of the abyssal depressions of the oceans, and I believe holds 
the opinion that the continents have occupied their present positions 
through all geological time, excepting as having developed in size, 
somewhat in the manner suggested by Dana and Le Conte.' In a 
late number of “Nature,” without committing himself to any of 
the views just enumerated, Mr. Moseley, F.R.S., says that there were 
no signs of submerged continents discovered by the soundings and 
dredgings of the Challenger. Dr. W. B. Carpenter, in the “ Nine- 
teenth Century,” has also written in favour of these new views of 
the general permanence of the present main features of the continents 
and oceans. Professor Alex. Agassiz, in ‘‘ Nature,” called attention 
lately to the fact that his distinguished father was one of the first to 
propound the view that the ocean basins are of great antiquity. 
1 For some of Mr. Murray’s views on the subject see a paper by him ‘On the 
Structure and Origin of Coral Reefs and Islands,’’ Proc. Roy. Soc. of Edin. April, 
1880, published in abstract since the above was penned. 
' DECADE II.—yOL. VII.—NO. IX, 25 
