| 释义 |
‖ atoll|əˈtɒl, ˈætɒl|
In 7 atollon.
[adoption of the native name atollon, atoll, applied to the Maldive Islands, which are typical examples of this structure; prob. = Malayalam aḍal ‘closing, uniting’ (Col. Yule).]
A coral island consisting of a ring-shaped reef enclosing a lagoon. Darwin's theory, now generally accepted, is that the lagoon occupies the place of a submerged island.
1625Purchas Pilgrims ii. 1648 Every Atollon is separated from others, and contaynes in itselfe a great multitude of small Isles..Each of these Atollons are inuironed round with a huge ledge of rocks. 1832Lyell Princ. Geol. II. 285 In the centre of each atoll there is a lagoon from fifteen to twenty fathoms deep. 1859Darwin Orig. Spec. xii. (1873) 324 Such sunken islands are now marked by rings of coral or atolls standing over them.
b. Comb. and attrib.
1842Darwin Coral Reefs 107 An atoll-shaped bank of dead rock. Ibid. 169 True atoll-structure. 1845― Voy. Nat. xx. 468 The foundations, whence the atoll-building corals sprang. |