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澎湖群岛位于我国台湾岛和大陆之间的台湾海峡中央,在台湾海峡位置偏南,距离台湾本岛最短距离约25海里,西与福建沿岸相距约80海里,由100多个大小不等的岛屿和岩礁所组成,分布在东西宽约40km、南北长约70km的海面上。最北端为目斗屿,最南端为七美屿,最东端为查母屿,最西端为花屿。陆地之总面积约为127km2,其中以澎湖本岛、白沙岛和西屿(渔翁岛)最大,占群岛总面积的80%以上。除花屿由安山岩组成外,其余各岛屿均由玄武岩、沉积夹层岩、凝灰岩与火山碎屑岩构成,分布十分广泛,保留完整,是台湾西部火山区的代表。澎湖玄武岩的钾氬定年和动物化石资料表明岛上火山活动约自17 Ma开始,而至8 Ma停止,以10~14 Ma为最盛期。
Penghu Islands is located in the center of the Taiwan Strait between Taiwan Island and mainland China, south of the Taiwan Strait, about 25 nautical miles from the mainland of Taiwan and about 80 nautical miles from the coast of Fujian Province to the west. It consists of more than 100 islands of different sizes and Rock reefs, distributed in the east-west width of 40km, about 70km north-south sea. The northernmost is Douduu Island, the southernmost tip of the Seimei Island, the easternmost end of Cham Island, the westernmost flower island. The total land area is about 127km2, of which the island of Penghu, Baisha Island and Xiyu Island are the largest, accounting for more than 80% of the total area of the archipelago. Apart from the ancients of Yuanyu, the rest of the islands are composed of basalt, sedimentary disseminated rock, tuff and volcaniclastic rocks. They are widely distributed and remain intact, representing the volcanic area in the west of Taiwan. Potassium-argon dating and animal fossil data from the Penghu basalts indicate that the volcanic activity on the island started at about 17 Ma and stopped at 8 Ma, with the peak at 10 ~ 14 Ma.