208 



DEPTHS OF THE OCEAN 



Rock frag- at depths ranging from 318 to 3420 feet during the expeditions of H.M. 

 merits dredged ships "Triton" and "Knight Errant." It suggests that the glaciated 

 stones on the ridge are or have been embedded in a boulder clay. The 

 stones are composed chiefly of Lewisian gneiss and the Moine schists 

 lying to the east of the post-Cambrian displacements in the Highlands 

 of Scotland. A large proportion consists of Caithness flagstones and 

 other Old Red Sandstone rocks, like those occurring in place in the 



Orkney and Shetland 



' ^^^ Isles. A considerable 



number of Jurassic and 

 Cretaceous types occur 

 in the collection, together 

 with two carboniferous 

 specimens, the age of 

 which is determined 

 by their fossil contents. 

 The assemblage of fossil- 

 iferous stones are similar 

 to those found by Messrs. 

 Peach and Home in the 

 boulder clays of Caith- 

 ness and Orkney. 



On the Faroe Banks 

 the volcanic rocks of the 

 Faroe Isles are not re- 

 presented among the 

 rock fragments dredged, 

 which would seem to 

 point to the extension of 

 the combined Scottish 

 and Scandinavian ice- 

 sheets over that part of 

 the sea-floor during the 

 glacial period. 



Just inside the Rock- 

 all Bank, at Stations 

 100 and loi (" Michael 

 Sars "), only one Old Red 

 Sandstone boulder was 

 found in the materials 

 collected, but the sand 

 grains occurring in the 

 ooze are either red or green. The ooze also contained fragments of 

 brown glass, resembling the slaggy volcanic rocks of Iceland. Such 



AO 



80 



— I — 

 120 



6 //YCHES 



160 MM. 



Fig. 



50. — Diagrams drawn to scale showing positions 

 OF Stones embedded in the deposit, the shaded 



PARTS indicating THE PORTIONS PROJECTING ABOVE 

 THE DEPOSIT. 



distributed by floating ice. 



At Station 3 ("Knight Errant"), at a depth of 318 feet, many 

 dead shells of shallow-water habitat were got, which clearly indicate a 

 subsidence of the sea-floor since the glacial period. The absence of 

 raised beaches in Orkney and Shetland, the submerged peat-mosses, 



