TEMPERATURE 91 



exceeding 40° F. The mean temperature of 

 all the observations taken at a depth of 500 

 fathoms works out at about 40° F. , so that on 

 the average all the water in the ocean deeper 

 than 500 fathoms may be said to have a tem- 

 perature below 40° F. ; this would be equal to 

 about 87 per cent, of the entire ocean. 



The most striking fact revealed by deep-sea 

 observations of temperature in all latitudes is 

 the very low temperature of the ocean at great 

 depths, say over 2000 fathoms, even under 

 the equator. Throughout this true deep-sea 

 region the temperature is but a very little way 

 above the freezing point of fresh water, and 

 the range, except in a few restricted regions, 

 does not exceed 2° F. The ooze dredged 

 from the ocean-floor in the tropics is so cold 

 that it cannot be handled without discomfort. 

 The lowest deep-sea temperatures are found 

 in those parts of the ocean which lie in the 

 southern hemisphere, and on the whole higher 

 temperatures are encountered on receding 

 from the Antarctic regions ; the lower deep-sea 

 temperatures extend farther to the north 

 from the Southern Ocean over those depths of 

 the sea which appear to have uninterrupted 

 communication with the south, that is to say, 

 are not cut off by any intervening submarine 

 ridges separating them from the cold waters 

 of the Antarctic. 



