SEA-FLOOR DEPOSITS. PART I 303 



in these deposits. In samples from Sts. WS 468 and WS 469 tests of Globigerina occur, 

 but their broken and worn appearance suggests that they are drifted material. The 

 characters of a sample from Drake Strait (St. WS 403) are less easy to interpret. The 

 coarser fraction contains many tests of Globigerina and rotaline Foraminifera together 

 with Radiolaria, but mingled with these are abundant angular sand grains up to o-i mm. 

 across ; the abundance of the latter prevents classification as an ooze. On the other hand, 

 the finer fraction is mainly of diatomaceous origin ; this and the terrigenous matter seem 

 to determine the deposit as a diatomaceous mud, despite the presence of the Fora- 

 minifera. St. WS 403 lies within the limits of a belt through Drake Strait considered by 

 Pirie to consist of diatom ooze. 



With regard to the sample from Bouvet Island, St. 117 lies well within the belt of 

 diatom ooze as indicated on the maps of Murray and Pirie. Both these observers would 

 doubtless classify the sample as diatom ooze, but they constantly remark that the de- 

 posits of this area are not typical diatom ooze. 



Glauconitic mud. Most of the glauconitic deep-sea deposits in the Discovery 

 collection are from the South African region (p. 304), but two stations, far removed 

 from that area, must be considered here. About 80 miles east of the Falkland Islands 

 (Sts. WS 433 and WS 518) glauconitic mud was dredged from depths of 1035 and 

 1258 m. In each sample grains of glauconite are seen infilling the broken tests of 

 Foraminifera, and the shape of other grains is consistent with formation within such 

 shells. The localities are near the south-western margin of the Globigerina ooze belt, and 

 they may be within the overlapping limits of the cold north-flowing Antarctic Drift and 

 the warm south-flowing extension of the Brazil current. The occurrence of glauconite 

 here is therefore in accordance with prevalent theories regarding the conditions under 

 which the mineral is formed. 



Terrigenous deposits. It is only to be expected that sediments of detrital origin do 

 not occur to any great extent in this oceanic region. Twelve stations, however, have 

 yielded samples of terrigenous deposits ; eleven of these are classed as sands and one as 

 terrigenous mud. The latter is a rather sandy grey mud obtained at St. J in a depth of 

 892 m. St. J is about 150 miles north-east of the Falkland Islands, which lie on an 

 extension of the Patagonian continental shelf; the station appears to be situated on the 

 somewhat steep gradient which slopes rapidly to oceanic depths. The deposit is there- 

 fore consistent with a situation within the influence of detritus-bearing currents. Even 

 so, the paucity of organic remains is remarkable. 



The sands are from widely separated localities, each of which may be discussed 

 separately. Sts. 235, 236 and 237 to the north-east of the Falkland Islands have yielded 

 sands from depths of 600, 612, and 904 m. respectively. Evidently these stations lie on 

 an easy gradient which continues northwards to about lat. 47 , where it begins to slope 

 more rapidly to oceanic depths. The occurrence of these sands is consistent with north- 

 flowing currents bearing detritus from the Falkland Islands area. 



The samples from St. WS 317 and WS 319 appear to be incomplete; indeed the record 

 of the latter sample in the Station List bears a note, " finer material from bottom sample 



