MAP OF THE NORTH POLAR OCEAN AND BORDERING LANDS WITH THE CONTINENTAL PLATFORM INTERVENING.

PROF. HULL ON DR. NANSEN'S BATHYMETRICAL RESEARCHES, ETC. 215

listening to Dr. Nansen at the meeting of the Royal Geographical Society on Tuesday last, and hearing the statement of his discoveries in the Arctic Ocean and along the coast of Norway, it occurred to me that it might be interesting to you if I was to give you (in brief) some account of these discoveries in connection with those which we ourselves have already considered at the meetings of the Institute. I have therefore prepared this communication, which is entirely extempore, and which will be illustrated to a certain extent by lantern slides.

1. The Atlantic border.-Now for those present who have not previously had an opportunity of investigating the sub-oceanic physical features of the Atlantic, and the North Sea and Arctic Ocean, I have just drawn here on the board an outline of what these physical features are, in cross sections. They are really very simple in detail. They consist first of the sea margin of the Atlantic; then of a platform, the margin of which has generally a steep descent into the abysmal ocean; this is called "the Continental Platform," on which the continent of Europe and the British Islands and Norway are practically built. This great platform extends along the sea coast and westward to Greenland, and southward along the coast of Europe and Africa. Then we come to the outer margin of the continental platform, where the descent of the sea-bed down into the abysmal ocean, to a depth perhaps of 6,000 or 7,000 feet below the present surface, becomes steep and abrupt. But when we come to Norway we find there, according to Dr. Nansen's views, instead of having one platform coming out from the coast, there are really two; one being "the coast platform," which is just a little above or below the actual level of the sea, and which contains principally all the little islands which lie off the coast of Norway, between which and the coast cruisers and yachts can sail in smooth water, while outside there may be a stormy sea. This is the "coast platform," which is different from the continental platform, and probably of more recent origin. The continental platform has been recognised by the soundings as far south as the Congo and on northward into the borders of Europe.

Then, we come to the coast of Europe; here we have most beautifully defined river valleys, as for example that of the Tagus, coming down across the platform, and with their channels descending to about 6,000 feet below the level of the ocean.

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Then, the Adour, which also, according to my investigations, certainly comes down to a similar depth, about 6,000 feet, Dr. Nansen in his work on the Polar ocean (vol. iv) when describing the Adour river valley, says: "it is almost impossible to give any other explanation of its existence than that of a former river valley at a time when the whole region was elevated into land." This, you will admit, is very valuable testimony.

Then we proceed northwards and find that the channels of several of the rivers entering the ocean from Spain and France are also continued out into the ocean across the platform, and descend almost to a similar depth as the base of the platform itself.

Similar is the case with the British Isles. In the case of one of the old river valleys, we have an illustration of a submerged valley in the English Channel; and it is remarkably determined and represented on the Admiralty Chart under the term of the Hurd Deep." It is 60 miles in length, running up the channel parallel to the coasts, along the centre between the coasts, and it terminates towards the Straits of Dover, gradually dying out where we may suppose the river had its origin; it also dies out towards the western margin of the continental platform, doubtless owing to silting. The floor of the English Channel itself, and of the Irish Channel, are only parts of the great submerged plain of the continental platform; but this is a river valley cut out and left open to the present day, so that the Admiralty surveyors have marked it as the Hurd Deep, after the name of the naval officer who carried out the soundings whereby the river valley was discovered.

2. The Arctic Ocean.-Nansen's great discovery, partly from actual soundings, partly by inference based thereon, is the occurrence of a profound Arctic basin which, unless abruptly terminated by the uprise of a mountain mass several thousand feet in height from its floor under the pole, of which there is no evidence, necessarily extends under the pole itself. (See Plate.) This view is strongly supported by Professor Spencer in an able paper which has opportunely reached my hands in which the whole question is discussed-and which is illustrated by an excellent little map of the Arctic regions. In this map, which is to some extent based on that of Nansen, in his great work,† but also on original researches, it is shown how the continental platform

* No. 11 in the list of papers appended to this essay.

✦ Bathymetrical Features of the North Polar Sea, Christiania, 1904.

is in all probability carried right round the whole of the great polar basin from the coast of Norway, by Spitzbergen, Franz Joseph Land, the New Siberian Islands, the coast of Alaska, Prince Patrick and other Polar islands; then off Banks Land, by the north coast of Greenland and onwards by Iceland to the North Sea and the Scandinavian coast from which we started. On this platform or continental girdle, which seldom exceeds 600 feet in depth from the surface at its outer margin, are planted all the groups of Arctic and sub-Arctic islands, including Iceland, Spitzbergen, Franz Joseph, Nova Zemlia, New Siberia, those between Beaufort Sea and Baffin's Bay, and the British Islands themselves. The breadth of the platform is greatest between Spitzbergen and the Scandinavian coast, here inclosing the Barents sea; and off the coast of Siberia the average breadth is about 500 miles. On the other hand, off the coast of Spitzbergen and apparently adjacent to Franz Joseph Archipelago the shelf has a breadth of only about 30 miles; and is a little over 60 to 100 miles off the Archipelago of the Greenland sea, as far as can be conjectured from the few soundings available. But all the soundings made by Nansen and previous explorers go to show, that on reaching the outer margin of the shelf, the land descends rapidly to depths of about 6,000 to 7,000 feet and more. As is well known, Nansen's Farthest North was reached on the 7th April, 1895, in lat. 86° 13′ 6′′ where the depth of the ocean reaches 3,000 mètres (9,780 feet) a depth which may be presumed to extend to the pole itself;-much too near to allow of the uprise of land of 10,000 feet in height within so short a distance.

On this subject we have an interesting statement from Professor Spencer, in which he says, "I was in northern Norway when the Ziegler expedition sailed, and hearing of their expectation of finding polar land, I felt that disappointment was in store for them; for Dr. Nansen's great discovery of a profound Arctic basin, immediately beyond the border of the continental shelf, precluded the probability of finding land between Franz Joseph land and the pole, or indeed along this line for a thousand miles beyond." The members of this expedition were doubtless unacquainted with the physical conditions of the Arctic region as now brought to light by the restoration of the old marginal land indicated by the continental platform and its deep basin adjoining.

It now only remains to observe that these Arctic sub-oceanic features resemble those of the coasts of Europe and America in being intersected by the channels of former rivers crossing