澎湖海洋地質公園 PENGHU MARINE GEOPARK 文化與旅遊篇 Culture & Travel Volume 赤嶼蕈狀石 赤嶼壺穴 Chihyu's mushroom rock Chihyu's pothole 北寮半島潮間帶岩脈 Rock vein in the intertidal zone of Beiliao Peninsula 46 46 47 47