THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 19 



found at such a depth. At the next station in 2391 fathoms (lat. 18° 29' S., 

 long. 130° 51' W.), the deposit was Ked Clay containing 18 per cent of 

 calcium carbonate; thence northwards the deposit continued to be Globi- 

 gerina Ooze with a percentage of calcium carbonate exceeding 60 as far as 

 lat. 5° S., then, finally, a peculiar Red Clay was met with at 1955 fathoms 

 (lat. 10° 38' N., long. 106° 48' W.), containing no calcium carbonate. 



Types of Deposits. 



The deposits obtained during this cruise of the U. S. S. " Albatross " all 

 belong to "Deep-sea Deposits" found beyond the 100-fathoms line. The 

 ordinary classification still holds good in this case, and the material at hand 

 gives typical examples of both terrigenous and pelagic deposits. As may be 

 expected from the configuration of the eastern shores of the Pacific, the ter- 

 rigenous deposits form only a narrow belt along the continental shelf of 

 North and South America, We have there Blue Muds, Green Muds, and 

 Green Sands, giving place to pelagic deposits as the depth increases towards 

 the open sea. 



Pelagic Deposits. Glohigerina Ooze was the deposit most frequently met 

 with, 36 samples having been studied. As regards the organisms that make 

 up the calcium carbonate, it was at first proposed to give a complete list 

 of the various species of Foraminifera, but as no difference could be found 

 between the organisms of the successive stations, the Foraminifera are 

 indicated merely as pelagic or bottom-living. The pelagic Foraminifera 

 usually present are : Glohigerina bulloides, Globigerina conglohata, Glohigerina 

 cequilateralis, Globigerina rubra, Glohigerina dubia, Glohigerina sacciilifera, Orhu- 

 lina iinivcrsa, Sjjhceroidina dehiscens, PuUenia ohliqiiilocidata (very frequent), 

 PidvinuUna menardii, and Pidvinulina tumida. Fishes' teeth and Echinoid 

 spines are the most frequent calcareous remains that accompany the 

 Foraminifera.^ 



Red Clay. The collection contains sixteen samples of Red Clay. The 

 deepest sounding where this deposit was found was at 3120 fathoms, and 

 the shallowest 1955 fathoms, the average depth being 2404 fathoms. The 



' The determination of the percentage of calcium carbonate was done througliout by means of 

 the method based on the displacement of carbonic acid by an acid and loss of weight, a modification 

 of Mohr's apparatus being used. This method is quite accurate and sensitive enough for the purpose, 

 especially as calcium carbonate cannot be equally distributed throughout a sample, even when small, 

 as is naturally the case with a deposit that has not been chemically, but mechanically, laid down, the 

 size and abundance of the constituents varying continually, as may be expected from their organic 

 origin. 



