THE DEPTH OF THE SEA.

Bruce Herald, Volume XIII, Issue 1209, 4 June 1880, Page 6

THE DEPTH OF THE SEA.

The superficial area of the globe is about 197 millions of square miles, some threequarters of which — viz , 140 millions of square miles — are covered by sea. The average depth of this enormous extent of sea is given by Sir Wy viile Thomson as 2500 fathoms, or 15,000 feet— something less than the height of Mont Blanc. This estimate however, probably refers only to the average depth of the great oceans, for a writer in the ' iSaturforscher,' who has reckoned in the gulfs and inland seas as well (soma of which, such as the Baltic, North fca, &,c , are quite shallow"), estimates the average depth of the whole sea at 1577 fathoms. The greatest depth yet certainly known is in the North Pacific Ocean. 11. M.5. Challenger sounded in 4575 fathoms — not quite five and a quarter miles- -in the channel separating the Caroline and the Ladrone Islands ; while tiierc are several spots to the east of the islands of Niphou and Yezo (Japan) where the depth exceeds 4000 fathoms, and another similar one close to the most westerly of the Aleutien Islands. The U.S. surveying ship Tuscarora has indeed sounded oil' the east coast of Japan, without finding bottom, iv 4G05 fathoms, but tho depth may not really have been as great as this, owing to currents in the water causing loops to form in the sounding line. Unless the sounding tube brings up a specimen ofthe bottom, or bears other evidence of its having been there, no "sounding'" can be considered as thoroughly satisfactory and trustworthy. The depth sometimes increases very suddenly. Thus, the Challenger found between the Admiralty Islands and Japan that the depth was suddenly more than doubled, increasing all at once from 200 fathoms on each side to 4500 fathoms, which would indicate the contour of the bottom in this locality as a deep submarine valley with very steep sides. The Atlantic is by no means so deep as the Pacific, ita average depth being estimated by Sir Wy ville Thomson at a little over 2000 fathoms. Its deepest partis in an area 400 miles long, extending along the meridian of 65 deg. W. longitude, and reaching 38 7 5 fathoms a little to the north of the Virgin Islands.