over geologic time the central volcano becomes extinct, followed by erosion and subsidence beneath the sea surface, leaving the coral reefs as a ring around (or cap on) the submerged island remnant.
由于侵蚀和海底的下沉,经过地质时代的变迁,中心的火山已经不见蹤影,而只留下珊瑚礁环绕或覆盖在沉入海底的火山岛上。