350 DR MURRAY ON THE DEEP AND SHALLOW- WATER MARINE FAUNA 



A wedge of cold water thus stretches northwards from the Antarctic Circle for more 

 than twelve degrees of latitude, being overlaid and underlaid by strata of a higher 

 temperature (see diagram). In the Antarctic Ocean the temperature of the water is 

 probably 28° or 29° F. (-2°'22 or-l°'67 C.) from the surface to the bottom, for the 

 temperature of the lower stratum decreases as colder latitudes are reached. One 

 remarkable fact brought out by these observations is that in latitude 50° S. the bottom 

 water has a temperature of 33° '5 F. (0°*83 C), which is very little different from the 

 temperature found all over the bottom in the Indian and other Oceans. The tendency 

 in a polar ocean, isolated from general oceanic circulation, is to produce a uniform 

 temperature of about 28° or 29° F., and this is the temperature actually observed in the 

 Norwegian Sea, north of the Wyville-Thomson Ridge, on which the depth is 250 

 fathoms (457 m.). There is no evidence at the present time of a similar condition of 

 things in the Antarctic or Great Southern Ocean. 



Salinity and Density of the Sea. — Mr Buchanan's observations on the density of 

 sea-water, and his experiments on the formation of sea-water ice, throw much light on the 

 causes of the remarkable distribution of temperature noted above. All the observations 

 made on water from the bottom or intermediate depths in the Southern Ocean, with the 

 density of the surface-water at each Station, are brought together in the following table. 1 



■Salinity of Water expressed as Density at S 



BOVF. 



89*-2ir. 



(s 1 ?^) 



1 >epth from which 

 Water was taken. 



Surface, . 



50 fathoms, 



100 ,, 



200 „ 



300 „ 



<00 „ 



Rottoni, 



Depth of 

 (fathoms), 



bottoi 





M 



:W 



.2 Igeo 

 3 *3 iD 



o <o ' 



w « 5 

 M ^5 



1-02657 

 629 

 616 

 593 

 572 

 579 

 607 



1900 



1-02516 



524 

 533 

 532 

 537 

 525 



1570 



1-02515 



512 

 535 

 534 

 536 

 550 



1000 



£2- 

 J'g'S 



-2 +3 bc 



1-02512 



1 -02561 



1260 



ohk 



1-02413 



... \ 

 .- i 



1 02567 

 1675 





iS +s fee 



►J ° 



1-02458 

 534 



(140fath.s.) 

 1-02547 



553 

 562 

 529 



1800 



.OQ' 



to _ • 



2, *i 6 o 





m * s 



1-02508 1-02509 

 507 



561 

 565 

 565 

 555 

 515 



1975 



37 



561 



1950 



. — 



od CO. 

 \Ci - ^ 



_ n <W 



Son 

 .2 « • _l 

 rf +j bo 



1-02522 

 522 



544 



548 



(315 faths.) 

 1 -02546 



554 



1800 



>o m co 



""" <M o 

 Bo O 



•_« -* rl 



CO « S 



p-J O 



.w 



- , ■* 



CM" 



M « = 

 \-i o 



1-02566 



1 -02564 

 2150 



1 -02570 

 576 

 565 

 573 

 560 



570 

 2600 



It will be observed that the salinities in the first column in lat. 3648' S. are higher 

 than in any other column; the water from surface to bottom bears evidence of having 

 been warmed and concentrated in tropical or sub-tropical regions, the position being 

 where the warm water of the Indian Ocean is carried southwards of the Cape of Good 

 Hope. The salinities of all the other columns are from stations within the zone of 

 1 See Challenger Report, Summary of Results, First Part, passim. 



