THE SUBMARINE BANK 149 



deeper than a hundred fathoms ; indeed in calm weather it is 

 said that the bottom may be seen in saihng between the two 

 atolls. 



To the north of Keeling the ridge probably stretches to Glen- 

 dinning Shoal — a reef of which I have no definite knowledge, 

 but I have been told by one of the captains of the Clunies- 

 Ross schooners that he has often seen the discoloration of 

 shallow water when on some of his numerous runs to Batavia. 



It would be of great interest to sound over this northerly 

 continuation of the ridge to determine its limits and its 

 characters. 



; Soundings directly to the south of the southern atoll are 

 also rather unsatisfactory, and the southern limits of the 

 submarine ridge are quite uncertain ; but it seems likely that 

 the southern slope is more abrupt than that in other 

 directions. 



Along the sounding-line to Java, I have examined samples 

 of the bottom brought up with the sounding-gear, and these 

 samples, on the whole, confirm the state of things shown in 

 the map of ocean bottom furnished in the Challenger re- 

 ports, where the atoll is shown to stand in the midst of an 

 area of Radiolarian ooze. 



I have not examined the samples obtained by the sounding 

 expeditions in the other directions, but the naked eye appear- 

 ance of the specimens is described by the staff of the cable 

 ships as being successively " coral fragments," " coral sand," 

 " fine sand," " sand and mud " ; and then, from a hundred 

 miles from shore and onwards, "brown mud" was the un- 

 varying nature of the bottom. In the neighbourhood of the 

 atoll, coral fragments and pieces of Nulliporce, with a coating 

 of a whitish clay, composed of GloUgerina and Orbulina 

 remains, constitute the commonest sample. Adown the sides, 

 of the submarine slope, to a depth of over 2000 fathoms, the 

 remains of organisms with calcareous skeletons far outnumber 

 the siliceous organisms, and Gldbigerina and Orhulina are the 

 predominant forms. This is the " fine sand " and " sand and 

 mud " ; its colour is greyish, and it has a distinct granular 



