2 2 Depth of the Ocean. 



W., she crossed the apex of a plateau which rises to less 

 than 1500 fathoms from the surface, and the base of which, 

 extending from Juan Fernandez to Magellan Strait, attaches 

 itself to the South American continent. It seems, therefore, as 

 if an almost uninterrupted area of elevation crossed the whole 

 basin of the Pacific in a north-westerly direction from Patagonia 

 to Japan. The tendency of most of the submerged ridges of 

 this ocean to follow the same direction has been frequently com- 

 mented upon, and, as is the case with the submerged plateaux of 

 the Indian and Atlantic Oceans, their association with centres of 

 volcanic activity is equally evident. 



The track of S.M.S. "Gazelle" in the South Pacific lay to 

 the westward and southward of that of the " Challenger," and 

 her soundings have proved the existence of an area of depression 

 with depths of from 2600 to 2900 fathoms, bounded on the west 

 by New Zealand, the Kermadec group, the Friendly Islands, 

 and the Samoan Islands, and on the north by the Cook Islands, 

 and the Tibuai or Austral Islands. It extends with lessening 

 depths eastward towards Patagonia, along the southern edge of 

 the above-described plateau, and probably communicates with 

 the deep areas to the northward in the space between the 

 Samoan group and the Society Islands. This southern area of 

 depression, however, may be considered as belonging not so 

 much to the Pacific as to the Southern Ocean. 



A line passing from Kamtschatka over Japan, the Ladrone, 

 Caroline, Marshall, Gilbert, Ellice, Sarnoa, Tonga, and Kermadec 

 Islands to New Zealand, divides the main basin of the Pacific, 

 of an average depth of 3000 fathoms, from the much shallower 

 seas lying to the westward, and may possibly have formed the 

 coast-line of a large continent which existed at a remote epoch 

 in the history of the surface of our planet, and the boundaries 

 of which have since been driven back to the present confines of 

 Asia and Australia. 



