172 GEOLOGY OF QUEENS1.AND COAST, 



were once hills oa the dry land would now be islands between the 

 Barrier and the main, such as Sir C. Hardy's Island and those 

 about it. Islands that once existed in front of the mainland 

 would now be altogether submerged, and their places only marked 

 by detached reefs outside the Barrier, such as those north and 

 south of Wreck Bay. According to the old rule of high land and 

 deep water going together (in other words, the slope of the ground 

 below water being only a continuation of that above), we should 

 have the Barrier much closer to the present land in its more 

 abrupt and lofty portions than in those which were lower and 

 less highly inclined. We see accordingly the reefs approach the 

 present land about Cape Melville, where the land is steep and 

 lofty, and recede from it as we go further north in proportion as 

 the land becomes flatter and more gentle in its inclination. Deep 

 holes and ravines, full perhaps of fresh water, may have existed 

 on the old land, so that when the surface of these lakes and 

 hollows first sank to the surface of the sea, and admitted its 

 waters, the bottom may have been too deep for the coral animals 

 to live on. This would explain such a phenomenon as the deep 

 narrow channel just north of Sir C. Hardy's Islands, with reefs 

 running along each side of it. In short, every modification in the 

 form and structure of the reefs is explicable by this h3"pothesis, 

 and many difficulties solved, which admit of no other explanation.' 



" He assumes, as we do, that the Australian coast at one time 

 was just within the line of the present Barrier Reef; but it seems 

 to me that the causes given by Jukes for the formation of the 

 Barrier Reef are equally well explained by erosion and denuda- 

 tion. He assumes a great thickness for the corals on the outer 

 edge of the Barrier Reef, — a thickness to have grown b}' the 

 synchronism of the subsidence and the growth of the corals, — a 

 thickness the extent of which no one can even guess at. We 

 assume for the corals a thickness that can be determined fairly 

 accurately as only a veneer of at most 20 fathoms upon the faces 

 of the denuded platforms of the islands which once formed the 

 outer line of the Australian continent. . . ."' 



