W. M. Davis — Shaler Memorial Study of Coral Reefs. 235 



that a continental shelf of one origin extends along the whole 

 coast ; but unlike Guppy, Vaughan recognizes the submergence 

 that the coast has suffered, and explains the Barrier reef as 

 having grown up only on the warmer, northern part of the 

 shelf — the Queensland border — during and after submergence. 

 On this point the following comments are offered : 



As far as the shelf south of the reef — along the New South 

 "Wales border — is concerned, it may well be the result of inor- 

 ganic marine processes of abrasion and deposition during a 

 long still-stand period before the recent submergence of the 

 continental margin ; during the same still-stand period, indeed, 

 as that in which the Queensland coast was, as Andrews has 

 shown, worn down to a lowland. There is good reason for 

 supposing that the still-stand period was preceded by flexure, 

 which uplifted the interior highland belt and depressed the 

 coastal margin and the adjoining belt of the sea floor; and if 

 so, it is reasonable to suppose that then, as now, the warmer 

 sea-floor belt was, during and after submergence, the seat of an 

 upgrowing barrier reef, which in the later stages of the same 

 still-stand period was broadened by lateral growth, just as the 

 present barrier reef is now broadening; and that still later the 

 lagoon was tilled with coral sand from the reef, with organic 

 deposits of local origin, and with land waste from the coast. 

 Thus a great terrace-like rampart — the total mass of the coral 

 reef, in the large sense of that term — was added to the Queens- 

 land border, in such form that, although above instead of 

 below water, it imitated in a general way the form of the inor- 

 ganic shelf farther south ; for surely there is no sufficient rea- 

 son for doubting that coral reefs 'could be formed along the 

 Queensland border before the recent submergence just as well 

 as afterwards. The chief differences between the northern 

 and southern — the Queensland and the INew South Wales 

 — parts of the shelf before submergence would have been 

 determined, as they are now, by the presence of the Barrier 

 reef. Where it grew, the exterior marine agencies could work 

 only on the breakwater formed by its organic mass, while far- 

 ther south they could work on all the shallow sea bottom and 

 on the edge of the continent as well. There they must have 

 abraded a shallow platform along the shore, and carried out the 

 detritus thus derived, as well as that received from the rivers, 

 to build the outer border of the shelf. In both parts of the 

 shelf there must have been large deposits of land waste 

 brought down by rivers, just as there is to-day, because the 

 coast of both parts rises rapidly inland to a well-watered high- 

 land. The occurrence of such detritus in abundance is expect- 

 able in an inorganic continental shelf formed along a still-stand- 

 ing coast of rather strong relief long subjected to erosion ; it is 



