340 IF. M. Davis — The Great Barrier Reef of Australia. 



On the other hand, Yanghan, while recognizing recent sub- 

 mergence of small amount as the cause of upgrowth of the 

 visible barrier reef from a platform now about 30 fathoms 

 below sea-level, has excluded coral-reef agencies from any part 



Fig. 1. 



in forming the platform itself, and has thus limited the thick- 

 ness of the reef to a small fraction of the thickness that is 

 implied bv Darwin's theory: Yaughan concludes that "the 

 living barrier reef is growing on what was a land surface in 

 Pleistocene time;'' hence "the idea that the platform was 

 formed bj infilling behind the reef may be permanently set 

 aside."* Both Gardiner's and Yaughan's views as to tlie thick- 



* T. W. Vauglian . . . The Virgin Islands . . . and their bearing on the 

 coral-reef problem. Bull. Geol. Soc. Amer., xxvii, 41-45, 1915. 



