THE EXTENT AND DEPTH OF THE SEA.

New Zealand Graphic, Volume XIV, Issue III, 19 January 1895, Page 55

THE EXTENT AND DEPTH OF THE SEA.

As it is hopeless to do more, we will briefly sketch the amount of our knowledge. First, as to the greatest depths known. It is very remarkable, and from a geological point of view, significant, that the very deepest parts of the ocean are not in or near their centres, but in all cases are very near land. One hundred and ten miles outside the Kurile Islands, which stretch from the northern point of Japan to the north-east, the deepest sounding has been obtained of four thousand six hundred and fifty-two fathoms, or twentyseven thousand nine hundred and thirty feet. This appears to be in a deep depression, which runs parallel to the Kurile Islands and Japan ; but its extent is unknown, and may be very large. Seventy miles north of Port Rico, in the West Indies, is the next deepest cast known—four thousand five hundred and sixty one fathoms, or twenty seven thousand three hundred and sixty-six feet; not far inferior to the Pacific depth, but here the deep area must be comparatively small, as shallower soundings have been made at distances sixty miles north and east of the spot. A similar depression has been sounded during the last few years west of the great range of the Andes, at a distance of fifty miles from the coast of Peru, where the greatest depth is four thousand one hundred and seventy five fathoms. Other isolated depths of over four thousand fathoms have been sounded in the Pacific. One between the Tonga or Friendly Islands of about four thousand live hundred fathoms, one of four thousand four hundred and seventyeight fathoms near the Ladrones, and another of four thousand four hundred and twenty-eight fathoms near Pylstaart Island, all in the Western Pacific. They all require further investigation to determine their extent. With these few exceptions the depths of the oceans, so far as yet known, nowhere comes up to four thousand fathoms, or four sea miles ; but there can be little doubt that other similar hollows are yet to be found. The sea with the greatest mean depth appears to be the vast Pacific, which covers sixty-seven millions of the one hnndred and eighty-eight millions of square miles composing the earth’s surface. Of these one hundred and eighty-eight millions, one hundred and thirty seven millions are sea, so that the Pacific comprises just one-half of the water of the globe, and more than one-third of its whole area. The Northern Pacific has been estimated by Mr John Murray to have a mean depth of over two thousand five hundred fathoms, while the Southern Pacific is credited with a little under two thousand four hundred fathoms. These figures are based on a number of

soundings which cannot be designated otherwise than as very sparse. To give an idea of what remains to be done, 1 will mention that in the eastern part of the Central Pacific there is an area of ten million five hundred thousand square miles in which there are only seven soundings, while in a long strip crossing the whole North Pacific, which has an area of two million eight hundred thousand square miles, there is no sounding at all. Nevertheless, while the approximate mean depth 1 am mentioning may be considerably altered as knowledge increases, we know enough to say that the Pacific is generally deeper than the other oceans. The immensity, both in bulk and area, of this great mass of water is difficult to realise ; but it may assist us when we realise that the whole of the land on the globe above waterlevel, if shovelled into the Pacific, would onlv till one seventh of it. The Indian Ocean, with an area of twenty live million square miles, has a mean depth, according to Mr Murray, of a little over two thousand fathoms. This also is estimated from a very insuflicient number of soundings. The Atlantic, by far the best sounded ocean, has an area of thirty-one million square miles, with a mean depth of about two thousand two hundred fat homs.