50 THE DEPTH AND MARINE DEPOSITS OP THE PACIFIC OCEAN. 



(3) The large rock fragments are broken masses of an impure limestone, 

 showing in some cases traces of bedding, whilst other blocks are compact. A 

 microscopic slide showed no trace of organisms, but the blocks were subse- 

 quently broken into smaller fragments, and in some parts numerous shells of 

 Foraminifera belonging to one of the Textularidae (probably BoUvina) could 

 be seen crowded together. The same fossil occurs in the small pebbles de- 

 scribed above. 



An unusual interest attaches to this deposit : a Diatom Ooze formed in 

 tropical latitudes, and yet free from the remains of lime-secreting organisms. 

 It is also curious that it should contain so many large fragments of rocks of 

 continental origin, and that small mineral particles should be so scarce. It 

 may be that in this case the large masses have not the same source as the 

 mineral particles, but were carried to this point by some such agent as 

 the roots of a floating tree, and that they happened to be in the way of the 

 trawl, although otherwise quite rare. The descriptions of the samples from 

 neighboring stations show that the abundant deposition of siliceous remains 

 in this region is extremely local. 



No. 14. Station 4675, 22nd November, 1904. 

 Lat. 12° 54' S. ; long. 78° 33' W. ; depth, 3120 fathoms. 



RED CLAY : very little material available, greenish-brown, soft, and plas- 

 tic, emitting a faint mouldy smell. 

 Calcium carbonate : per cent. 

 Eesidue: 100 per cent: — 



Siliceous Organisms (0 per cent) ; none could be observed in the portion 

 of the sample taken for examination. 



Minerals (traces), angular, mean diameter 0.06 mm. ; augite and fels- 

 par are the principal constituents; felspars are represented by oligoclase 

 and andesine ; common grass-green hornblende is also fairly abundant. 

 Strangely enough, a few undoubted rounded grains of glauconite are to be 

 found, difEering in no way from the typical glauconitic grains of a Green 

 Mud. 



Fine Washings (nearly 100 per cent), greenisli-brown, ilocculent matter, 

 with a very large proportion of minute particles of the above-mentioned 

 minerals. 



