Pacific Islands Oceania

PACIFIC ISLANDS (OCEANIA). The Pacific islands, also sometimes spoken of collectively as Oceania or even Oceanica, may from a geographical point of view, be described as including all the almost innumerable "oceanic" islands, as distinguished from the "coastal" archipelagoes adjoining the shores which more or less surround the Pacific Ocean, i.e., those which obviously pertain physically to the coasts of Australia with its Territory of Papua, and those of New Zealand, and the shores of America on the east and again on the west of this great ocean.

No entirely satisfactory classification of these islands seems to have been suggested. The one most commonly put forward is to treat them as divisible, in accordance with the native races found in occupation at the time when Europeans first entered this area, into the three areas of Polynesia, Melanesia, and Micronesia; Polynesia (Gr. roXbs, many, and vficos, island) being the eastern part of the area embracing Hawaii, the Ellice, Phoenix, Union, Manihiki and Marquesas groups, the Cook, Society, Tubuai and Tuamotu groups and many other lesser islands; Melanesia (Gr. pLaas, black, and island), being the area in the western and south-central area embracing in some interpretations New Guinea and the Louisiade islands and, in addition, the Solomon, Santa Cruz, New Hebrides, New Caledonia and the Loyalty islands, the Fijian islands, and the intervening groups; Micronesia (Gr. puKpos, small, and viicros, island), the third and smallest of the divisions lying north and somewhat east of Melanesia, and embracing the Marianas, Palau (Pelew), Caroline, Marshall and Gilbert islands.

The Structural Arcs and Geology.—Several great zones of deep water may be traced in the Pacific Ocean. The first is east of the Ryukyu islands and the Philippines, and beyond it far out to sea rise the island chains which stretch in scattered order from south-east Hondo, Japan, to the Ogasawara Jima (formerly some times called Bonin islands) between lat. 28° and 26° 3o' N., the Volcano islands (lat. N.), the Marianas, Yap and the Palau (Pelew) islands.

Islands of the Asiatic Continental Edge.

The Ogasawara Jima include nummulitic limestone with ancient igneous rock and there are also newer (horizontal) limestones abutting against the above. The Volcano islands are said to continue the line of Fujiyama. In the southern Marianas terraces of coral formation rise to the summits, but in the north the coral is restricted to the bases. Yap is formed of basic volcanic material. The Palau islands have a volcanic foundation on which rests a f ossiliferous limestone that is more or less crystalline. Malakal in this archipelago reaches a height of over 1,600 feet and syenitic pebbles occur even on this high ground. The island chains above discussed have been thought by Suess to mark the limit of the continental mass of Asia, in which case they may be said to mark the edge of the easternmost of a series of steps, the edges of which may be indicated by the Ryukyu, Corea and the Khingan Mts. Beyond the Ogasawara Jima-Palau zone to the east is one of the world's chief lines of sea-deeps, 4,000 fathoms being much exceeded over long distances.

Western Pacific Arcs. Introductory.—From the south-east of the Marianas another zone of deep water extends north-eastwards to the west-north-west end of the Hawaiian chain, beyond which again is another great deep. From the east-south-east end of the Hawaiian chain another zone of deeps extends south-south-west wards to the vicinity of East Cape, New Zealand with a south eastward extension east of Chatham island (q.v.). The expanse of ocean extending south-westwards between the two deep zones, Marianas-Hawaii and New Zealand-Hawaii, is marked by islands set in arcs. These arcs are rather a series of overlapping sub parallel lines than strictly continuous curves. Arcs of the western Pacific farther and farther away from Australia show less and less traces of continental land, and mountain folding and volcanic lines, usually with atolls, are all that remain. The western Pacific arcs have been thought to be in relation with those of both New Guinea and New Zealand.