LOST WORLDS

Otago Daily Times, Issue 22744, 3 December 1935, Page 18

LOST WORLDS

LAND BENEATH THE SEA The discovery of the wreck of the Luisitania off the Irish coast is one of the most recent dramas of a fascinating modern science—undersea exploration. Lost continents as well as lost ships lie beneath the sea, and we are gradually learning more of them. A new mountain peak has been found in the Atlantic by a French cable ship, the Ampere. It is only 195 feet below the surface (writes R. L. Hadfield, in the Sydney Telegraph). i The Ampere was engaged in repairing j the submarine cable between Brest and | Casablanca, a cable which, formerly Ger- j man, was cut and diverted by a British ; vessel during the war, when it discovered the peak. Its position is 35.5 N. and 13.55 W., that is. about 400 miles -west of Gibraltar. To the oceanographer the discovery of a new feature of this description is every bit as thrilling as would be a new Matterhorn to the mountaineeer or geographer. It adds one more item to his considerable knowledge of that part of the earth’s surface which lies under water and which is, of course, greater than the unsubmerged area. Within the past 50 years oceanography has become a true science, and as a result of expeditions sent by scientific societies and of Government surveys almost the whole of the bed of the sea has been mapped and explored . with the same thoroughness as is exhibited by ordnance surveyors at work in the valley and on the hills of dry land. Within the last two years discoveries in the sea have strengthened belief m the former existence of the continent of Gondwanaland, lying between India and South Africa. What are believed to be the highest peaks of this continent reach above the surface of the sea, and are known to us as the Seychelle Islands. One of the most interesting discoveries in connection with this “ lost continent is the fact that across a great submerged plain lies a deep gully, conjectured to be the ancient bed of the River Indus. These discoveries link up with previous knowledge of another submerged land, the “ Empire of Zabedj,” between the coast of China and Ceylon, and tend to prove that the Indian and Pacific Oceans were once dry land, with the present islands of Polynesia as mountain peaks. Survey ships and cable ships are now provided with instruments with which the sea-bed can be explored with almost as much thoroughness as if divers went down with note book and pencil. The chief instrument for this purpose is the sounding machine, of which there are two types, the wire-and-sinker type and the sonic type. The first, as its name implies, incorporates a wire (pianowire) and a weight. The weight carries down with it brass tubes open at the bottom; these are forced into the bottom by the momentum of the drop, and thus take samples of the ground. The tubes can only be used in the case of comparatively soft sea-bottom; when this is hard, an instrument known as a a snapper ” is used. The snapper incorporates two jaws, kept apart by a finger; on hitting the bottom the finger is displaced. the jaws close with a snap, and thus bite out a sample of the soil. In addition, it is usual to take the temperature of the water at the bottom of he sea, this information being necessary to submarine-cable manufacturers. Curiously enoXigh, the temperature of the sea bottom is much the same over about 87 per cent of the sea’s entire area, being about 35deg. Fahr., whether at the Equator or in the North Sea. The heat from the sun penetrates less than 25 fathoms below the surface. When no samples or temperatures are required, the Sonic sounder is used. This instrument incorporates a gongi hammer and microphone. Its principle is the catching of an echo from the bottom of the sea, calculation from the time taken for .Um echo to return, giving the depth of water. The gong, hammer, and microphone are attached to the ship’s skin below the water line, leads from the latter being taken to headphones in the ship’s wheelhouse. The navigator listens to the headphones, and watches a dial marked off in fathoms. When the needle on the dial points to zero a blow on the gong is given, and at the same time the needle begins to move, the instrument being so adjusted that when the navigator hears the echo the number on the dial to which the needle points is the depth in fathoms. One of the great advantages of this sounder is that the ship does not have to be stopped, and only when taking very deep soundings—when, of course, the echo is faint—do any extraneous noises in the ship, such as the chipping of rust from anchor cables, have to be stopped. Such instruments as these, combined with the “dredge” with which shellfish and other living organisms are brought up from the bottom, are enabling the extent, shape, and nature of all the land lying under’ the sea to become known to us, and in some cases very strange discoveries have been made. For instance, in a great area in the Gulf of Oman, near Muscat, the seabottom smells like rotten eggs through the presence of sulphuretted hydrflgen, and is absolutely devoid of living creatures. It is supposed that there is great seepage into the sea from petroleum regions in the very bowels of the earth.