NARRATIVE OF THE CRUISE. 435 



to 20 per cent, of the deposit, the whole of the remainder consisting of the frustules of 

 Diatoms and the skeletons of Radiolarians. The dredgings in these deposits yielded, 

 in addition to all the varieties of rocks mentioned in the blue muds farther south, several 

 fragments of pumice stone, basaltic volcanic rock, palagonite, and one or two fragments 

 of a compact limestone and sandstone. 



Between hit. 53° and 47° S. two soundings were obtained in 1800 and 2150 fathoms. 

 The deposit in each case was a whitish Globigerina ooze, containing respectively 85 and 

 89 per cent, of carbonate of lime, which consisted chiefly of Coccoliths, Coccospheres, and 

 pelagic Foraminifera belonging to the species Globigerina bulloides, Globigerina injlata, 

 Globigerina dubia, Pidvimdina micheliniana, and Orbidina universal, together with 

 other Foraminifera and fragments of Echinoderms. The mineral particles appeared to 

 make up 2 to 4 per cent, of the deposit, and consisted of hornblende, magnetite, felspar, 

 vitreous fragments, and a few quartz grains. There were 4 or 5 per cent, of Diatoms and 

 Radiolarians in these Globigerina oozes. 



The remaining variety of deposit (red clay) was obtained in lat. 42° S. at a depth of 

 2600 fathoms. It contained 18 per cent, of carbonate of lime, consisting of fragments 

 and perfect shells of Globigerina bulloide,s, Globigerina injlata, Globigerina rubra, 

 Pidvimdina micheliniana, Orbidina univerm, a few other Foraminifera, Coccoliths, and 

 fragments of Echinoderms. The mineral particles made up 19 per cent, of the deposit, 

 and consisted of felspars, hornblende, augite, magnetite, pumice, and fragments of volcanic 

 glass, grains of peroxide of manganese, with a mean diameter of about 0'05 mm., while 

 a few rounded fragments of quartz reached a diameter of 0"5 mm. The remainder of the 

 deposit consisted essentially of argillaceous matter with very minute fragments of crystals 

 and pumice. There was a larger percentage of carbonate of lime in the upper layers of 

 the deposit than in the lower ones. The trawl brought up 10 or 12 litres of manganese 

 nodules, pumice stones, fragments of palagonite, ear-bones of Cetaceans, and Sharks' teeth. 



From the foregoing description it appears that the deposits forming at the most southerly 

 points reached by the Challenger are composed chiefly of continental debris carried into 

 the ocean by the floating ice of these regions, and that this material makes up less and 

 less of the deposit as the distance from the Antarctic Circle increases until it completely 

 vanishes about lat. 46° or 47° S. The deposits along the Antarctic Ice Barrier, which 

 have been called blue muds, resemble in many respects the deposits formed at similar 

 depths off the Atlantic coast of British North America. The nature of the rock fragments 

 dredged in these latitudes conclusively proves the existence of continental land probably 

 of considerable extent within the Antarctic Circle. One of the fragments of gneiss 

 dredged from a depth of 1950 fathoms measured 50 by 40 centimetres, and weighed more 

 than 20 kilogrammes. In the region occupied by the Diatom ooze, northward of the 

 blue muds, the predominant feature of the deposit is due to the innumerable frustules of 

 Diatoms and skeletons of Radiolarians which have fallen from the surface and sub- 



