,v DEPTHS AND DEPOSITS OF THE OCEAN 143 



rise based on a sounding in 2600 fathoms occurs between two 

 soundings in 3100 fathoms, and the floor of the deep sinks from 

 this rise towards the east to the maximum depth of 2)ZZ7 

 fathoms. 



C/mn Deep hes in the North Atlantic between lat. 20" and Chun Deep. 

 29^ N., and is very pecuHar in outhne ; it is estimated to cover 

 an area of about 159,000 square miles, and the greatest depth 

 is 3318 fathoms. 



Challenger Deep lies to the east of the Ladrone Islands in challenger 

 the western Pacific, and extends from lat. 11' to nearly 20° N., ^^'"^i"- 

 covering an area estimated at about 129,000 square miles. In 

 1875 the "Challenger" recorded a depth of 4575 fathoms 

 between Guam and the Pelew Islands, and in 1899 the United 

 States steamer " Nero" took a sounding in 5269 fathoms to the 

 south-west of Guam, which is the deepest sounding hitherto Deepest 

 recorded. The 4000-fathoms area extends in a narrow trench bounding. 

 as far to the north-east of the "Nero" sounding as the 

 "Challenger" sounding is south-west of it, and a small isolated 

 area occurs still farther north, based on a single sounding in 

 4204 fathoms. At a comparatively very short distance from 

 this deep trench is a pronounced rise within the deep based on 

 three soundings : one in 1800 fathoms and two in 1000 fathoms ; 

 another slight rise is based on a sounding in 2900 fathoms. 



The remaining deeps are smaller, and need not be referred 

 to in detail, their position being clearly shown on the accom- 

 panying map (Map II.). Attention may be drawn, however, 

 to the great depth of the Planet Deep, situated in the tropical 

 Pacific between the Solomon Islands and New Pommerania, in 

 which a sounding in 4998 fathoms was recorded in 19 10 by the 

 German survey ship "Planet" a short distance to the west of 

 Bougainville Island. 



2. Deep-Sea Deposits 



The systematic investigation of deep-sea deposits was first First 

 undertaken by Sir John Murray during the "Challenger" Ex- sJudy'oV 

 pedition, and the only standard work dealing with the whole ™_f^^".^^ 

 subject is Murray and Renard's " Challenger''' Report on Deep- ' 

 Sea Deposits, published in 1891. That Report was not based 

 merely on the deposit-samples brought home by H.M.S. 

 " Challenger," though the detailed descriptions were limited 

 to those samples, but included the results of the examination 

 of samples collected by many other ships, received at the 



