228 CORAL AND ATOLLS 



lagoon, still Sir John Murray has shown quite conclusively that 

 matter is being removed in suspension. At p. 515 (op. cit.) 

 he says : " Very strong currents run out of the entrances into 

 lagoons and lagoon channels, and when the tow-net was used, 

 it showed that a large quantity of coral detritus was being 

 carried seawards." 



This is an easily verified observation, but it needs some 

 amplification, for it is only true for certain inlets, or at 

 certain states of the tide. If other inlets had been visited, for 

 instance those on the windward side, or if the turn of the 

 tide had been awaited, then currents running into the lagoon 

 would have been detected, and their burden of detritus would 

 have been found to be even greater. In the Cocos-Keeling 

 atoll. Dr. Guppy estimated "that at least 5000 tons of sand 

 and debris derived from the breaker edge of the reef are 

 annually transported by the currents through the passages 

 between the islands into the lagoon, nearly all of which is 

 deposited at or near the lagoon's margin." The importance of 

 this water-borne sand will be dealt with more fully, but the 

 undoubted fact of its coming to the lagoon in greater quantities 

 than it leaves it, negatives the idea that, even in suspension, 

 matter is commonly robbed from a lagoon. 



Besides this failure of the common history of atoll lagoons 

 to show any signs of the action of " solution," or to demand 

 any such explanation for their origin or development, there 

 is an inherent improbability in the theory as a whole. 

 Darwin, on the very first publication of the theory, detected 

 this weakness, for in a letter written to the late Mr. T. Mellard 

 Reade on September 22,1880 (quoted in Nature), he says : "It is 

 astonishing that there should be rapid dissolution of carbonate 

 of lime at great depths and near the surface, but not at the 

 intermediate depths where he places his mountain peaks." 

 This is of course a very pertinent point, and one that does 

 not appear to have had any definite answer, although it was 

 again raised by Dr. R. von Lendenfeld in Nature of May 8, 

 1890. Dr. Lendenfeld sums up the stages as follows: 

 " First a limestone cone is built, because the lime is deposited 



