672 DR J. H. HARVEY PIRIE ON DEEP-SEA DEPOSITS 



CaCO^ 40 per cent. : — Foraminifera. Coccoliths fairly abundant, no rhabdoliths. 



Residue red in colour. 



Siliceous organisms 3 per cent. : — ^Diatoms, radiolaria, sponge spicules. 



Minerals 1 per cent. : — The only recognisable piece is a fragment of pumice 

 0*75 mm. in size. 



Fine wasliings bQ per cent. : — Similar to No. 50, but distinctly more amorphous 

 clay, almost sufficient to term the deposit a transition form to Red clay. 



A feiv small pebbles from trawl, angular and sub-angular. Probably ice-carried 

 from their variety, but no striae seen on any of them. (Specimens lost.) 



Chief foraminifera : — Glohigerina bulloides and G. infata are the most numerous 

 forms. Fewer bottom-living forms than in No. 50. Truncatulina seems to take 

 the place of Lagena so far as numbers go. Arenaceous types include Psammosphxra 

 fusca, Rhabdamniina discreta, and Proteonina diffiugiformis. 



Summary of the Three Main Types of Deposits obtained. 



Globigerina Ooze. 



Samples of Globigerina ooze from the S. Atlantic were obtained by the Scotia in 

 two localities : (1) between Falkland Islands and the S. Orkney group, and (2) to the 

 south and east of Gough Island. In the former area the Globigerina ooze forms a narrow 

 zone between the S. American terrigenous deposits and the circumpolar Diatom-oozc 

 band. Only one typical sample was obtained in this locality, viz. No. 28, from 56° 54' S., 

 56° 24' W., 1946 fathoms, containing 24 per cent, of CaCOg by analysis, the lime 

 being chiefly derived from the shells of foraminifera, Mr Pearuey has separated no less 

 than twenty- nine genera and sixty species of foraminifera from this sample, of which 

 twelve genera are of arenaceous types. The calcareous forms include practically all 

 the types characteristic of the Globigerina oozes of the S. Atlantic, the most abundant 

 being the small cold-water forms Globigerina dutertrei,G. pachy derma, G. btdloides, and 

 G. infiata. The mineral particles of this deposit, like those of the Diatom oozes to the 

 south-east, are largely of volcanic origin. On the Burdwood Bank, although no ooze 

 was actually brought up in the sounding-tube, the material obtained in the trawl, 

 containing, as it did, much foraminifera and shelly, sandy material, points to the eastern 

 portion of the Bank at all events, if not the whole of it, lying within the Globigerina ooze 

 area, and outside the region of deposition of land-derived material from the S. Americau 

 continent. Some eighty species of foraminifera were obtained, the general facies 

 being an Antarctic shallow-water one, with few arenaceous species. 



South of Gough Island, on the Mid-Atlantic rise, the Globigerina ooze extends to 

 about 48° S. lat. Sample No. 47, from 48° 06' S., 10° 05' W., from a depth of 1742 

 fathoms, must be classed as a transitional form of deposit, containing, as it does, 55 per 

 cent. CaCOa, and also 30 per cent, of siliceous organisms. The foraminifera from this 

 place consist predominatingly of the cold-water Globigerinidae, G. infiata, G. dutertrei. 



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