CORAL REEFS 



173 



Barrier Reef and the coast of Queensland — but should the 

 land have been a small island which finally sank, then all 

 that would finally appear above the surface of the sea would 

 be a ring of coral surrounding a central lagoon, in other 

 words a typical atoll. This process will be made clearer by 

 a study of Figure 36, which shows the various stages in the 

 conversion of fringing reefs into atolls according to 

 Darwin's theory. 



At first this theory met with widespread support, notably 

 from an American geologist named Dana, who studied 

 many reefs, but as coral formations began to be studied in 

 more detail and with ever increasing care, it was found that 

 in many regions where corals flourished, so far from there 



Fig. 36. — Diagram to illustrate formation of Atolls and Barrier Reefs by sub- 

 sidence, according to Darwin's theory. A,A, Sea-level of island, with 

 fringing reef in black; A',A', the same after some subsidence — island, with 

 barrier-reef shaded ; A", A", the same after the island has been sub- 

 merged — atoll reef dotted. 



being any evidence of subsidence of the land, there was 

 definite evidence that the land was rising. Moreover, all 

 three types of reefs are sometimes present in the same area, 

 which is incompatible with Darwin's theory according to 

 which the presence of a fringing reef is evidence that the 

 land is stable while the presence of barrier reefs and atolls 

 is evidence that it is sinking. Again, Darwin'* theory 

 demands that an immense belt of land between the tropics 

 should have been steadily sinking over a long period of time, 

 which would be certainly a very remarkable fact, if true. 



