'THE PACIFIC BASIN. The configuration of the Pacific basin is quite irregular, although there are large areas where the bottom exhibits little relief. In general, the depth increases from southeast to northwest. A vast depression known as the Tuscarora deep extends from the Japan and Kurile islands eastward along the Aleutian chain toward the roast of North America. With in this area the depth exceeds 2000 fathoms and in places soundings of 4000 fathoms or more have been made. Another extensive deep lies south of the Tonga Islands, between the Chatham Islands and New Zealand on the west and the Maria Theresa Reef on the east. In the central part of the ocean are the Belknap, Miller, and Ililgard deeps. The deepest sounding-5269 fathoms—was made in 1900 off the island of Guam by the United States ship Nero. A sound ing of 5155 fathoms and another of 5147 fathoms have been made north of New Zealand. These depths are much greater than have been found in any other ocean. The most extensive plateau in the Pacific lies southeast of New Guinea and in cludes the Solomon, Ellice, Fiji, and Tonga islands, while a southern arm extends from the last-named group to New Zealand. The bottom
within this area rarely exceeds 2000 fathoms in depth and much of it is less than 1000 fathoms. Other plateaus are occupied by the Marshall and Gilbert groups, by the Caroline Islands, the Low Archipelago. and Hawaii. A broad continental shelf extends along the eastern coast of Asia, but the western shores of America slope abruptly to the ocean floor. The mean depth of the Pa cific is estimated at 2300 fathoms.
The proportion of land drained into the Pacific is insignificant when compared with the drain age received by the Atlantic. Its basin includes the generally narrow strip of the American con tinent to the west of the Rocky Mountains and the Andes, Melanesia. the Indo-Chinese States, China, a small part of Siberia, and eastern Aus• t ralia.