to Tanjong Berikat the Eastern point (), on to Tanjong Djemang () in Billiton, along the North coast of this island to Tanjong Boeroeng Mandi () and thence a line to Tanjong Sambar () the Southwest extreme of Borneo. On the East. From Tanjong Sambar through the West coast of Borneo to Tanjong Sampanmangio, the North point, thence a line to West points of Balabac and Secam Reefs, on to the West point of Bancalan Island and to Cape Buliluyan, the Southwest point of Palawan, through this island to Cabuli Point, the Northern point thereof, thence to the Northwest point of Busuanga and to Cape Calavite in the island of Mindoro, to the Northwest point of Lubang Island and to Point Fuego (14°08'N) in Luzon Island, through this island to Cape Engano, the Northeast point of Luzon, along a line joining this cape with the East point of Balintang Island (20°N) and to the East point of Y'Ami Island (21°05'N) thence to Garan Bi, the Southern point of Taiwan (Formosa), through this island to Santyo (25°N) its North Eastern Point. On the North. From Fuki Kaku the North point of Formosa to Kiushan Tao (Turnabout Island) on to the South point of Haitan Tao (25°25'N) and thence Westward on the parallel of 25°24' North to the coast of Fukien. On the West. The Mainland, the Southern limit of the Gulf of Thailand and the East coast of the Malay Peninsula. However, in a revised edition of Limits of Oceans and Seas, 4th edition (1986), the International Hydrographic Organization officially recognized the Natuna Sea. Thus the southern limit of South China Sea is revised from the Bangka Belitung Islands to the Natuna Islands. Geology The sea lies above a drowned continental shelf; during recent ice ages global sea level was hundreds of metres lower, and Borneo was part of the Asian mainland. The South China Sea opened around 45 million years ago when the "Dangerous Ground" rifted away from southern China. Extension culminated in seafloor spreading around 30 million years ago, a process that propagated to the SW resulting in the V-shaped basin we see today. Extension ceased around 17 million years ago. Arguments have continued about the role of tectonic extrusion in forming the basin. Paul Tapponnier and colleagues have argued that as India collides with Asia it pushes Indochina to the SE. The relative shear between Indochina and China