Early Theories of Atoll Formation

The earlier voyagers imagined that the coral-building animals instinctively built up their great circles to give themselves protection in the inner parts. This is so far from the truth that the massive kinds, on whose growth on the exposed outer shores the very existence of the reef depends, cannot live within the lagoon, where other, delicately branching kinds flourish. Moreover, this view supposes that many species of distinct genera and families combine for one end, and not a single instance of such a combination can be found in the whole of nature. The theory that has been most generally accepted is that atolls are based on submarine craters, but when we consider the form and size of some atolls and the number, proximity, and relative positions of others, this idea loses its plausibility. Thus Suadiva atoll is 44 geographical miles in diameter in one direction and 34 miles in another; Rimsky is 54 by 20 miles across and has a strangely sinuous margin; Bow atoll is 30 miles long and on average only 6 wide; and Menchicoff atoll consists of three atolls united, or tied together. This theory, moreover, is totally inapplicable to the northern Maldive atolls in the Indian Ocean (one of which is 88 miles long and between 10 and 20 miles wide), for they are bounded not by narrow reefs, like ordinary atolls, but by a vast number of separate little atolls, while other little atolls rise out of the great central lagoonlike spaces.