1869.] on the Scientific Exploration of the Deep Sea. 491 



rather inclined to the opinion that they have been derived from Ireland, 

 and not necessarily connected with any glacial phenomena, believing that 

 their presence may be accounted for by the ordinary action of marine 

 currents. 



" Pebbles from 1215 fathoms (Station 28)." 

 The stones were all subangular, the edges being all more or less worn or 

 altogether rounded off. The specimens were 38 in number, and upon 

 examination were found to consist of : — 

 5 Hornblende schist ; the largest of these (which also was the largest in 

 size of the entire series) weighed 421 gr. Q of an ounce), was ex- 

 tremely compact, and was composed of black hornblende, dirty- 

 coloured quartz, and some garnet. 

 2 Mica schist ; quartz with, mica, the largest weighing 20 grains. 

 5 Grey pretty compact limestone, the largest being 7 grains in weight. 

 2 Fragments (showing the cleavage faces rounded off on edges) of ortho- 

 clase (potash felspar), evidently derived from granite ; the largest of 

 the two fragments weighed 15 grains. 

 5 Quartz, milky in colour or colourless ; the largest of these weighed 

 90| grains, and showed evidence of having been derived from the 

 quartz-veins so common in clay-slate. 

 19 Fragments of true volcanic lava, most of which were very light and 

 — scoriaceous (vesicular), although some small ones were compact and 

 38 crystalline ; and in these the minerals augite, olivine, and glassy 

 felspar (Sanadine) could be distinctly recognized. Amongst these 

 were fragments of trachytic trachydoleritic, and pyroxenic (basaltic) 

 lavas, quite similar to those of Iceland or Jan Mayen of the present 

 period, from which they had probably been derived. 



"Gravel from 1443 fathoms (Station 20)." 

 This sample of gravel consisted of 718 subangular fragments, in general 

 not above from | to § grain in weight, with occasionally some of a little 

 greater size ; but the most considerable of all (a fragment of mica schist) 

 only weighed 3 grains. They consisted of : — 



3 Fragments of orthoclase felspar. 



4 Bituminous or carbonaceous shale (? if not accidental). 



5 Fragments of shell (undistinguishable species). 



4 Granite, containing quartz, orthoclase, and muscovite. 

 15 Grey compact limestone. 

 62 Quartzose mica schist. 

 317 Hornblende schist; sometimes containing garnets. 

 273 Quartzite fragments, with a very few fragments of clear quartz ; the 

 majority of the pieces being of a dirty colour, often cemented 

 together, were evidently the debris of quartzite rocks or beds of 

 indurated sandstone, and not from granite. 

 28 Black compact rock containing augite, most probably a volcanic 



basalt. 



718 



