130 BULLETIN OF THE 



has occupied a far longer period than that during which the northeast 

 coast was either stationary, or had been slightly elevated. He urges 

 the parallelism of the outline of the Great Barrier Reef with that of the 

 northeast coast as evidence that the circumstances which modified the 

 outline of the coast likewise determined the general outline of the reef, 

 while subsidence would most assuredly produce the results observed on 

 the northeast coast of Australia if the rate of growth of corals were 

 absolutely identical with that of the subsidence of the bottom of the 

 sea. With our present knowledge of the mode of coral reef formation, 

 it seems unnecessary to explain the existing state of things by a sub- 

 sidence coincident in rate with the growth of corals, when observation 

 plainly shows us that there has been only a slight elevation or a stationary 

 condition of the coast line. Starting from the conditions Jukes imagines 

 to have existed before the subsidence took place, only leaving the coast 

 nearly at its present level, we can imagine a fringing reef to have been 

 formed slowly, and to have little by little extended seaward, advancing 

 more slowly as the depth increased, while the talus for the upper limits 

 of coral grew, it increased in thickness, and to have ended in a barrier 

 and inner reef with channels very much like the reef we find to-day. 



Is it credible that, along the whole length of the northeast coast of 

 Australia, the subsidence should, for a length of over one thousand 

 miles, be so nearly identical in amount as to have ended in forming 

 pai*allel to it the Great Barrier Reef? The same question is one which 

 must be answered not only for Australia, but for all the atolls and 

 barrier reefs in the Pacific and other regions where such reefs exist. 



We have all over the world many positive proofs of the elevation of 

 the land, sometimes on a gigantic scale, as in South America, for instance, 

 up to nearly three thousand feet. Neither can we deny that there are 

 many points, especially in the Pacific Ocean, where are to be found 

 areas of subsidence ; but it is by no means proved that this subsidence 

 has been the main cause of the formation of atolls or of barrier reefs. 

 In fact, all the later investigations of coral reefs have, without exception, 

 rejected Darwin's theory of subsidence as explaining the formation of 

 reefs, and they have looked to other causes, which seemed to them more 

 natural, as probably more efficient in the growth of reefs. The ques- 

 tion is not whether subsidence has taken place even in the areas where 

 atolls or barrier reefs occur, — this may be considered as proved, — but 

 whether this subsidence has absolutely kept pace with the rate of growth 

 of corals. It is remai-kable that Darwin, who is so strongly opposed to 

 all cataclysmic explanations, should in the case of the coral reefs cling 



