650 DK J. H. HARVEY PIRIE ON DEEP-SEA DEPOSITS 



Diatom oozes, although there is still a very large proportion of mineral particles. The 

 preliminary reports sent home by Dr Heim (3) of Lieut. Filchner's Expedition show 

 that still further to the east, in the neighbourhood of S. Georgia, the Diatom ooze band 

 extends considerably further to the north than is shown on the Challenge!' map, in 

 that published by myself in the Scot. Geog. Mag. in 1905 (4), and in Murray and 

 Philippi's Valdivia report (5), and its limits must apparently be extended so as to pass 

 to the north of S. Georgia, but here again radiolaria form a considerable part of the 

 siliceous contents. 



Two samples obtained somewhat to the west of the southern end of the Sandwich 

 group were too fragmentary to determine with any exactitude, but appear to be 

 transitional between Diatom oozes and glacial clays. 



B. Weddell Sea. — All the samples obtained in the Weddell Sea to the south of the 

 60th parallel consist of material almost entirely of terrigenous origin, and are dealt 

 with at length (p. 677 et seq.) under the heading "Terrigenous Deposits, particularly 

 Glacial Muds and Clays." 



C. Between 60° S. latitude, Gough Island, and S. Africa. — Five samples (Nos. 

 45 to 49) were obtained along the meridian of 10° W. long., between 60° S. latitude, 

 and Gough Island ; two between Gough Island and Cape Town. 



In this area the northern boundary of the Antarctic glacial clay lies probably a 

 little north of the 60th parallel, and the transition from it to the Diatom ooze band 

 must be a fairly sharp one. Sample No. 44 (from lat. 61° 21' S., long. 13° 02' W., 

 2764 fathoms) is a tough clay approximating in some respect to an abyssal Red clay, 

 although differentiated by containing a large amount of the finest rock flour of terri- 

 genous origin. Not a single diatom, however, could be found in it, whereas in No. 45 

 (from lat. 56° 58' S., long. 10° 03' W., 2518 fathoms) siliceous organisms constitute 

 55 per cent, of the whole deposit, diatoms forming the greater part of this. This 

 deposit is not, however, a typical Diatom ooze, but is intermediate in type between it 

 and a volcanic sand. It contains 40 per cent, of minerals, mostly of evident volcanic 

 origin. This point is about midway between Bouvet Island and the Sandwich group, 

 both volcanic in nature ; but considering the prevalent westerly winds in this region, 

 the latter is the source from which the pieces of pumice and volcanic minerals have in 

 all probability been derived. * 



In lat. 51° 07' S., long. 9° 31' W., 2103 fathoms (No. 46), the sounding-tube came 

 up empty, having been apparently on hard ground, but the trawl brought up a small 

 quantity of a characteristic Diatom ooze of a light straw colour when wet, almost pure 

 white when dry, and of a floury consistence with very little grittiness. The percentage 

 of siliceous organisms is as high as 80, diatoms predominating largely over radiolaria. 

 Mineral particles form only 5 per cent, here, whilst there is 9 per cent, of CaCOs, 

 chiefly foraminifera. 



In lat. 48° 06' S., long. 10° 05' W., 1742 fathoms, the bottom material (No. i7) 

 is transitional in type between Diatom ooze and Globigerina ooze, containing as it does 



