Taiwan and the Philippines are two neighboring island groups situated in the middle of the West Pacific island chain fringing the Asiatic continent. Marine Tertiary sediments constitute the bulk of the formations in these two island groups, and lie on a pre-Tertiary metamorphic basement which is characterized by the predominance of deformed sedimentary rocks and metarnorphosed volcanic rocks. Various kinds of schists are common in both regions. However, the old metamorphic basement of the Philippines is marked by the widespread intrusion of basic to ultrabasic igneous rocks whereas that of Taiwan is distinguished by the prolific development of crystalline limestone and some pegmatite minerals. The oldest dated formation in the metamorphic complex of Taiwan is Permian, while that ol the Philippines is Jurassic.