NOTES ON DEEP SEA SOUNDINGS. 67 



From these data Dr. Carpenter infers that between the Sand- 

 wich Islands and Japan there must have been " a great and rapid 

 subsidence within a very recent epoch." This, is, no doubt, a 

 just conclusion, for, as he states, the limit of coral growth being 

 about 20 fathoms, the seven elevations in the area named show 

 that the sinking was too rapid to allow of the corals being formed 

 up to the surface in the period of depression. The corals must 

 have been killed at the submersion of each elevation, as on the 

 slopes of the Bonin Islands. It is a fair illustration of Darwin's and 

 Dana's doctrines of the coral reef formations ; and the data also 

 show that there was once> chain of submarine volcanoes in that 

 part of the Pacific. The absence, moreover, of such coral islands, 

 as in the Central and Southern Pacific, shows also the rapidity 

 and perhaps recentness of the subsidence in the Northern por- 

 tion. I would remark, however, that this must have taken place 

 very recently indeed, if the view taken is correct, that the volcanic 

 islands lie along a line of elevation.* 



The great depth of the bottom in parts of the Pacific will, as 

 Dr. Carpenter deduces from the Tuscarora observations, render 

 the laying of a cable across that section unsuitable. The irregu- 

 larity of the bottom is also very great near the shores of Niphon, 

 Yesso, and the Kurile Islands, though a terrace exists at from 

 1,100 to 1,425, and 653 fathoms of depth ; for at the outside of 

 the ridge the fall was rapid to 3,587, 4,356, and 4,655 fathoms. 

 Even 100 miles south of Cape Lopatka, the extreme point of 

 Kamschatka, the depth was 3,759 fathoms ; and though it rose at 

 about 300 miles south of Behring's Island, to 1,777 fathoms, it 

 sank again rapidly to 4,037. Similar facts are stated of the 

 vicinity of the Aleutian group. South of the Alaskan Peninsula, 

 great and sudden changes of depth occurred ; but between 

 53° 35' N., and 60° W., and Vancouver's Island, for 1,000 

 miles, the bottom sloped upwards with little variation from 2,500 

 to 1,500 fathoms, and after another series of ups and downs from 

 1,007 to 1,300, it rose to within 100 fathoms along the North 

 American coast. Yellowish and clay-coloured mud and ooze 

 with grey and black sand, formed the specimens brought up, but 

 in one spot, at 3,439 fathoms, the bottom was formed of " hard 

 yellow sand with black specks." Dr. Carpenter ends his review 

 of the " Tuscarora's" researches in these words: — "Along the 

 whole of this route, except between the Peninsula of Alaska and 

 Cape Flattery, there was land at no great distance ; and there is 

 therefore no great difficulty in supposing that both the mud and 

 sand were derived from its disintegration. No indication is given 

 of organic constituents ; but I have reason to believe that a 

 microscopic examination of these Soundings would yield abund- 

 ance of siliceous exuviae." 



*See on this head some interesting remarks by Darwin {Structure and Dis- 

 tribution of Coral Beefs, 2nd. Edn., 1874, p. 184). 



