'f=^ OCT 1 1900 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. VI. 



No. IV.— APRIL, 1899. 



CD:RX(3-xi<rj^Xj -.^s-ticlies. 



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



By Wilfrid H. Hudleston, M.A., F.E.S., F.L.S., F.G.S., etc. 



{Concluded from the March Number, p. 105.) 



Part II. — The Icelandic Shallows.^ 



(PLATES V, YI, AND YII.) 



QUITTING 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 

 Feeroes 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 : — 



The Fseroe- Shetland Channel 319 fathoms. 



The Faeroe-Iceland Platform 277 ,, 



The Denmark Straits 319 ,, 



The Fseroe-Shetland Channel, sometimes known as the Lightning 

 Channel, is one of great interest to us. It runs up from the axis of 

 the Norwegian Atlantic in depths of about 600 fathoms, when it 

 suddenly abuts on the Wyville Thomson ridge, which is a kind of 

 submerged causeway running from the Shetland bank to the Fteroe 

 bank. The extreme depth, in the centre, to which this ridge is now 

 submerged, may be taken at 319 fathoms, or 1,914 feet. To make 

 things perfectly safe, we should require an elevation of this part of 

 the sea bed to the extent of 2,000 feet in order to walk over to 

 Iceland without wetting our shoes, and an equal amount of elevation 

 in the Denmark Straits would enable us to extend our journey to 

 Greenland. But it must not be supposed that an elevation of 

 2,000 feet would do more than produce a very narrow neck of land ; 

 and even an elevation of 3,000 feet, if Mohn's chart is to be relied 

 on,^ would still confine us to the use of the narrow Wyville 

 Thomson isthmus. It should be noted that the Lightning Channel 

 runs up in almost direct continuation of the axial depths of the 



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. 



2 According to Bartholomew's map illustrating Hansen's paper in the Geographical 

 Journal, the Lightning Channel is bridged by two submerged necks of laud. 



DECADE IV. VOL. TI. NO. IV. 10 



