Hostname: page-component-848d4c4894-m9kch Total loading time: 0 Render date: 2024-06-07T01:00:45.155Z Has data issue: false hasContentIssue false
  • English
  • Français

I.—Oceans and Continents

Published online by Cambridge University Press:  01 May 2009

T. Mellard Reade
Get access Rights & Permissions [Opens in a new window]

Extract

In 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.

Type
Original Articles
Information
Geological Magazine , Volume 7 , Issue 9 , September 1880 , pp. 385 - 391
Copyright
Copyright © Cambridge University Press 1880

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

page 385 note 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.

page 386 note 1 Geographical Evolution—Proc. Royal Geographical Society, 1879, pp. 422–43.

page 387 note 1 Dredging Operations of U. S. Coast Survey, Steamer “Blake,” 1879, Letter No. 3, pp. 294–5.

page 388 note 1 Mr. Murray says, in the paper before alluded to, on Coral Reefs, etc. (p. 507):— “The soundings of the “Tuscorora” and “Challenger” have made known numerous submarine elevations; mountains rising from the general level of the ocean's bed, at a depth of 2500 or 3000 fathoms, up to within a few hundred fathoms of the surface.”

page 388 note 2 Contributions to the Study of Volcanos, Geol. Mag. 12 II. Vol. III. 1876.Google Scholar

page 388 note 3 Dredging of the U. S. Steamer “Blake,” 1879, Letter No. 3, pp. 299&301. Alex. Agassiz speculates on the former connexion of the West India Islands with the continent of South America.

page 389 note 1 Mr. Gwyn Jeffreys, F.R.S., in a paper recently read before the Geological Society, seems also to have been impressed with the evidences of recent subsidence and elevation as an argument in favour of the older views as to continents and oceans.

page 389 note 2 Professor Judd writes me: “Why the mountain masses of the globe rise so little above the surface of the ocean I take to be due to the great rapidity of subaerial denudation in the higher regions of the atmosphere. The moon, which is a much smaller globe than ours, has much more prominent features. If the rate of waste gradually increases as we rise higher in the atmosphere (owing to inequality of temperature and condensation of moisture, etc.), then the tendency will be to keep down all great inequalities. All our mountains, therefore, are comparatively small, and all the highest are of recent formation geologically speaking.”

This reasoning I thoroughly agree with as regards mountain masses, but the small average elevation of whole continents above the sea-level I think points to the possible instability of other conditions, mechanically speaking, and to the probable mobility of the crust of the earth as regards large areas.

page 390 note 1 “Chemical Denudation in Relation to Geological Time,” pp. 49–50.