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I.—On the Eastern Margin of the North Atlantic Basin

Published online by Cambridge University Press:  01 May 2009

Wilfrid H. Hudleston
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Extract

Quiting the more northern parts of the great Atlantic depression, we have next to consider an extensive water-space of a much shallower character. Here the volcanic masses of Iceland and the Fseroes with their submarine attachments have produced a marked effect on the depths of the ocean. The Norwegian Atlantic connects with the main Atlantic by three straits, whose central channels present the following depths at their shallowest:—

Type
Original Articles
Information
Geological Magazine , Volume 6 , Issue 4 , April 1899 , pp. 146 - 157
Copyright
Copyright © Cambridge University Press 1899

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References

page 146 note 1 Figures 2, 3, and 4 (forming Plates V, VI, and VII), being reductions of portions of the Admiralty charts, are specially intended to illustrate Parts II and III.

page 146 note 2 According to Bartholomew's map illustrating Nansen's paper in the Geographical Journal, the Lightning Channel is bridged by two submerged necks of land.

page 148 note 1 DrThoroddsen, (“Exploration in Iceland“) speaks of fragments of a tableland, originally connected, forming a 3,000 feet thick layer of breccia, which covered the whole inner surface of Iceland, and which has been for the most part removed by erosion; the strata underlying the breccia is everywhere Tertiary basaft. Un- fortunately, the author does not say of what the breccia consists. (Geographical Journal, 11, 1898, p. 497.)Google Scholar

POSTSCRIPT.—In a letter dated Copenhagen, December 12, 1898, Dr. Thoroddsen states that he refers to the ancient volcanic palagonite breccia with smaller and larger fragments of basalt, dolerite, etc. It is obvious, therefore, that, so far as we know, all the materials which go to form this large island are of igneous origin, not excepting the Tertiary leaf-beds, which appear to owe their mechanical sediments exclusively to this source.

page 148 note 2 For a notice of Rockall, , see infra, p. 163.Google Scholar

page 152 note 1 Geographical Journal, 09, 1897, p. 273.Google Scholar

page 153 note 1 Trans. Victoria Institute, 1898.

page 153 note 2 At the meeting held in the Map Room of the Royal Geographical Society (Jan. 27) for the purpose of hearing and discussing Professor Hull's latest paper on this subject, some of the speakers were disposed to criticize his tracing of the old river-courses cut in the continental shelf-e.g. the River of the English Channel. But this really is a very minor matter, and altogether fails to touch his principal contention. Most persons who have paid attention to the physical geography, past and present, of these Islands agree that the area of the English Channel was at one time sufficiently elevated as to have been within the influence of meteoric erosion: a difference of 100 fathoms would more than effect this. Thus we may readily allow Professor Hull his rivers of the English and St. George's Channels, even if we are disposed to criticize the exact course they may have taken. But the deep sculpturing which he claims to have been effected in the suboceanic continental slope (the ‘escarpment’ of Professor Hull) by these same rivers involves considerations which would land us in serious difficulties. If the ‘edge’ or angle of the slope was at one time raised 1,000 fathoms above the level of the sea, instead of being 100 fathoms below it as at present,inthat case the region now occupied by the English Channel must have been raised to that extent or more, unless the River of the English Channel was endowed with the faculty of running up hill. Suppose we take the period as Pliocene: this means an upland of 6,000 or 7,000 feet above sea-level in the vicinity of the region now occupied by the Straits of Dover, whilst some sixty miles to the northwards the Crags were being deposited in a shallow sea, whose area is now partly occupied by the Suffolk coast. Truly,inthis case we should require another ‘escarpment’ facing the area now occupied by the North Sea to meet the difficulty. If we take the period as Pleisto- cene we are no better off. to enable the Kiver of St. George's Channel to surmount the edge of the ‘escarpment’ we must raise the drainage area behind, and this it would be difficult to effect without converting the Irish Sea into an inland lake over 6,000 feet above sea-level.

page 154 note 1 This point is now conceded by ProfHull, (see Geol. Mag., 03, 1899, p. 132).CrossRefGoogle Scholar