W. IT. Hudleston — E. Margin of N. Atlantic Basin. 99 



It will be gathered from the preceding extracts that Professor Milne 

 regards the suboceanic continental slope as an important factor iu 

 the tectonic history of the earth's crust. Looking at the subject 

 broadly, one might say that this suboceanic slope performs a double . 

 function. In the first place, as the more or less abrupt termination 

 of a continental mass, it affords relief to the periodic strain, and 

 thus becomes at times the seat of dynamic energies of great force. 

 Secondly, its more obvious function is to contain all but the surface 

 waters of the great oceans within its limits, and it thus becomes the 

 true margin of their respective basins. 



Trusting to be pardoned for what might seem at first sight 

 a digression, I will now direct attention to a few hydrographic 

 details with reference to the particular suboceanic slope under 

 consideration. We have already seen that it extends over 51° of 

 latitude. Allowing for sinuosities and for the easterly extension 

 beyond Spitzbergen, we are dealing with a marginal line which 

 cannot be less than 5,000 miles in length. The principal authorities 

 for these details, and also for the accompanying map, are as follows : — 



Nansen's paper " On some Results of the Norwegian Arctic 



Expedition." ^ 

 " The Physical Chart of the North Polar Regions," by Bartholomew.^ 

 " The Norwegian North Atlantic Expedition," by H. Mohn.^ 

 And lastly, several of the British Admiralty charts, e.g. : 



Chart No. 1, " British Islands to Mediterranean Sea," pub- 

 lished in 1884, with small corrections down to 1897. 



Chart No. 2, " The British Islands," published in 1884, 

 with small corrections down to 1894 and large corrections 

 down to 1896. 



Chart No. 1,104, " The Bay of Biscay," published in 1888, 

 with large corrections down to 1892 and small corrections to 

 1897. 



Chart No. 2,058, " North Atlantic Route Chart," published 

 in 1892, with small corrections down to 1897. 

 Also other Admiralty charts. 



It must be understood that the accompanying map has no claim 

 to accuracy of detail ; if a general impression is conveyed, that will 

 be sufficient for the purpose.* The ' edge ' or angle between the 



1 Geogr. Journal, May, 1897. ^ Ibid., June, 1897. * Christiania, 1887. 



* This remark refers to the large chart which was exhibited at the Bristol meeting. 

 Since then Messrs. Bartholomew have prepared a more elaborate map based upon 

 the outlines of that chart. This will serve to give a general idea of the subject of 

 the paper, viz. "The Eastern Margin of the North Atlantic Basin." It will be 

 readily understood that details can only be shown on a larger scale. Indeed, for very 

 close work in connection with the " suboceanic Continentcd slope,'''' it may be doubted 

 whether a sufficient number of reliable soundings have been taken as yet to warrant 

 any-detailed mapping of these slopes in some cases. Notwithstanding the imperfection 

 of the record, however, there are some features in the marginal line, such as the 

 ' Fosse de cap Breton,' which have been clearly established (see Fig. 4). It will be 

 observed that a very small area in Messrs. Bartholomew's chart, to the W.S.W. of 

 Madeira, shows depths exceeding 3,000 fathoms. This, however, has no bearing on 

 the subject of my paper. 



