86 DB. WAITJCH ON THE PHYSICAL 



a large proportion afc least, of the rock debris and volcanic detritus 

 which was found mixed with the mud in this region, I think there 

 cannot be a doubt as to these having been derived from the sources 

 suggested by the analyst. In most of the samples of mud obtained 

 in that oceanic area, and more particularly in the tract extending 

 across to the north-westward from the Faroes to Iceland, and again 

 from the north-western point of Eockall in a north-westerly direction 

 towards Cape Rekianess in Iceland, I almost invariably detected 

 more or less rock debris mingled with well-marked volcanic materials. 

 I shall show presently why I consider the specimen of Atlantic 

 mud analyzed by Mr. Porbes, to which such a prominent place has 

 been given, a most unfortunately chosen one. But meanwhile, I 

 would observe that there is every reason to believe that, in the open 

 portions of the North Atlantic, the really typical mud supposed to 

 represent the Cretaceous material is more or less entirely devoid of 

 debris of this kind. But, for all this, the subject is in many respects 

 puzzling and complicated, inasmuch as pieces of rock of considerable 

 size have undoubtedly been found by me in mud obtained at 

 such distances from land as to render it extremely unlikely that 

 they could have been drifted by even the strongest currents known 

 to prevail anywhere out at sea in those latitudes. Moreover, as this 

 occurs in oceanic areas which for ages have not seen the bottom of an 

 iceberg or even large masses of drift-ice — probably not since the 

 Glacial period — the rock debris can scarjsely be traceable to that 

 agency. Nor is it likely that it can have been transported and 

 dropped by fish ; for the question at once arises, Where could fish 

 get it from ? And surely the rock debris could not have lain to this 

 day in its present position at the sea-bed, uncovered, to any extent, 

 with sedimentary deposit, since the period when the areas in which 

 they occur were shoal-water areas, and therefore subject to the in- 

 fluence of currents capable of moving such masses to long distances*. 

 Under these circumstances it is desirable that the following ad- 

 ditional facts indicating the exceptional condition of the sea-bed in 

 the channel between the Bockall shoal and the north-west coast of 

 Ireland should be made more generally known than they appear to 

 be. It will be seen how well founded was Mr. David Porbes's sur- 

 mise that the volcanic detritus in the 1443-fathom mud had been 

 drifted either from Jan Meyen or Iceland, when I state that be- 

 tween the Faroes and the south-western part of Iceland there 

 exists a channel where we found a depth of 680 fathoms. The 

 sounding was a most important and interesting one, since it was 

 here that I obtained the first clear and really indisputable evi- 

 dence of the presence of animal life at such a depth. Prom the 

 nature of the creatures brought up, and a number of conclusive 

 facts to which I need not now refer more particularly, but which have 

 also already been fuUy described by me f, there are the strongest 



* This subject was fully discussed in a paper contributed by me to the 

 * Quart. Journ. of Science ' for Jan. 1864, and also in my ' North- Atlantic Sea- 

 bed,' pp. 3-7. 



t North-Atlantic Sea-bed, pp. 3-7 and 147. 



