iS 



NATURE 



[May 2, 1907 



NORTH POLAR PROBLEMS.' 



'T'HE deep North Polar Basin forms the northern termin- 

 ■*• ation of a series of depressions of the earth's crust ex- 

 tending north through the Norwegian Sea from the eastern 

 side of the Atlantic, and dividing between the continental 

 masses of the old and the new world. The eruption of 

 the Jurassic basalts of Kranz Josef Land and Spitsbergen 

 may have had some connection with the sinking in of the 

 North Polar Sea bottom, but the basin was probably to 

 a great extent formed before that time. Newer volcanic 

 rocks are not known hitherto from the edges of the North 

 Polar Basin. On Bennett Island, De Long reports lava 

 (or basalt), but we do not know its age. 



It is most iinprobable that any block of land (horst) 

 should have remained isolated in the middle of such a 

 basin, surrounded by deep water on all sides, and without 

 having any connection with the surrounding lands or 

 continental shelves. It is, therefore, of' essential import- 

 ance to determine the edge of the continental shelf off 

 the known coasts. But the edge of the North Polar 

 continental shelf is only known exactly in two places — 

 north-west of the New Siberian Islands and north of 

 Spitsbergen — whilst in the region between these two places 

 we know the deep sea to the north. In the remaining 

 part of the North Polar Sea we know as yet very little 

 about the edge of the continental shelf. 



The rule that the continental shelves are generally 

 much narrower outside high and mountainous coast than 

 off flat and low lands holds good only where the moun- 

 tain formations of the coast are in near relation to the 

 trend of the coast and to the continental slope outside, 

 and also where the mountainous coast is built up by 

 primary rocks. This seems hardly to be the case on the 

 northern coast of the American Arctic Archipelago and 

 Greenland, although there are rather high promontories 

 in some places. It is, therefore, difficult to say much 

 about the extent of the continental shelf there. It is 

 perhaps more the case along the north coast of Alaska, 

 and therefore the continental shelf may possibly be 

 narrower in that region ; but even this is uncertain. The 

 deeper soundings taken near the supposed edge of the 

 shelf may simply indicate depths of submarine valleys, 

 which may be numerous in this region, and many more 

 and deeper soundings are required before we can say any- 

 thing with certainty. 



Dr. J. \\'. Spencer's conclusions as to the width of the 

 continental shelf (American Journal of Science, vol. xix., 

 No. 113, May, 1905), drawn froin the great depths of 

 the submarine fjords of the American Arctic Archipelago, 

 are hardly well founded. Considerable depths of the sub- 

 marine valleys and channels (fjcrds) do not point to a 

 comparatively narrow shelf in regions where there has 

 been glacial erosion. It ought also to be considered that, 

 on the whole, the region of the .American Arctic .Archi- 

 pelago exhibits geomorphological features which are 

 exceptional. This region was probably near the heart of 

 the great North -American Ice agr, and the land has been 

 split up into islands and peninsulas, whatever the original 

 cause of this dissection might have been. 



It cannot, therefore, be said that the geomorphologic 

 features of the known part of the Arctic regions exclude 

 the possibility of a wide extension of the continental shelf, 

 possibly with lands on it, into some parts of the Unknown 

 North.' 



The Sea Currents and the Drift of the Ice seem to 

 indicate that there is an extensive area of sea to the 

 north of the Frani's track. Peary's experiences during 

 his latest expedition also indicate that there is much sea 

 to the north of Greenland. The ice-drift converges 

 towards the opening between Greenland and Spitsbergen. 

 Peary's observations of a rapid eastward ice-drift also 

 indicate that there cannot have been much land to the 

 east of his northward track ; but as we do not know the 

 depths over which Peary travelled, we cannot say much 

 with regard to the possibility of land or continental shelf 

 further north and east. 



The drift of the Jeanette can hardly be said to indicate 



1 Abridged from a paper by H.E. Dr. Fridtjof Nansen, G.C.V.O., read 

 before the Royal Ge0gmphic.1l Society on April 29. 



NO. 1957, VOL. 76] 



land to the north, as this drift was chiefly influenced by 

 the winds. 



My conclusions with regard to an actual current in the 

 surface-layers of the North Polar Basin, pointing towards 

 Franz Josef Land and Spitsbergen (" The Scientific From 

 Report," vol. iii.), might seem to indicate that there was 

 land to the north, and that the North Polar Basin is a 

 long and narrow depression. For, owing to the earth's 

 rotation, we might c.\pect a surface-current of this kind 

 to be deflected towards the coast on its right-hand side, 

 i.e. towards the Greenland and American side. It is, 

 however, probable that the winds and ice-drift in the un- 

 known parts of the sea might have influenced the direc- 

 tion of our drift, and that therefore the results arrived at 

 as to the direction of the current are not quite correct. 



R. A. Harris's contention that the difference in the 

 magnitude of the iiilt-s on Bennett Island and the coast 

 of Alaska proves the existence of extensive land to the 

 north is based on a much too scanty material of observ- 

 ations. On the northern coasts of Franz Josef Land I 

 found a smaller tide than the Jeanette -(.'eople on Bennett 

 Island. 



The possible differences shown by the ice in the Beau- 

 fort Sea, on the coast of Prince Patrick Island, north of 

 Ellesmere Land and Greenland, and in the sea crossed by 

 the Fram, cannot be said to point to the existence of 

 land in the Unknown North. 



The occurrence of driftwood on the northern coasts, and 

 even on the floe-ice itself (north-west of Greenland), proves 

 that this ice must have drifted across the unknown sea 

 from Siberia or America. The great quantity of " post- 

 Glacial " driftwood, found even at high elevations on 

 the now ice-bound coasts in the north, points to a milder 

 period in post-Glacial times with a more open North 

 Polar Sea. 



.Methods of Exploration. — The drawback with sledge 

 journeys acro.ss the Polar ice is that they do not give 

 much opportunity of soundings and oceanographical work ; 

 but something could be done by a practical equipment. 

 Determination of the edge of the continental shelf would 

 be most important, but also some observations of the 

 temperature and salinity of the deep-water strata of the 

 deep sea beyond this edge would be of value. 



A drift with a ship across the Unknown North from the 

 sea north of Behring Straits or Western Alaska, and 

 towards Greenland, would give important results, and 

 could be done probably in five years, although the drift- 

 cask of Bryant and Melville took nearly six years from 

 Alaska to Iceland (from September 13, 1899, to June 7, 

 1905): 



SEISMOTECTONIC LINES.' 

 T N studying the distribution of the towns and villages 

 ■'■ damaged by Calabrian earthquakes. Prof. Hobbs finds 

 that they show a noteworthy tendency to grouping along 

 series of essentially parallel straight lines (seismotectonic 

 lines), which he believes are related to coast-lines, borders 

 of mountain-masses, boundaries of geological formations, 

 &c. The places most seriously damaged are generally 

 situated at or near the intersections of indicated seismo- 

 tectonic lines, while these lines often intersect lines of 

 volcanoes (volcanotectonic lines) at volcanic vents. In the 

 direction perpendicular to seismotectonic lines, he states 

 that the destructive intensity of the waves falls off rapidly, 

 having but little effect upon well-built houses more than 

 a mile distant, except in the case of earthquakes of the 

 first order of intensity. He therefore concludes that " the 

 destructive violence of an earthquake is localised on 

 vertical planes of fracture within the earth's crust; along 

 which cracks the seismic waves are transmitted with the 

 least loss of intensity." 



The district chiefly affected by the Calabrian earthquakes 

 is one in which the peculiar earth-sounds, known as 

 brontidi, mistpoeffers, &c., frequently occur. Recent in- 

 vestigations by Cancani, .Alippi, and others have shown 



1 (i) "On some Principles of Seismic Geology"; (s) " The Geotectonic 

 and Geodynamic Aspecis of Calabria and North-Easlern Sicily, a Study in 

 Orientation." By William Herhert Hobbs. (.Blilrage zur Grofkysik, 

 Bd. viii., pp. 219-362, and plates.) 



