BY PROFESSOll STEPHENS, :M.A. 603 



archipelago, lapped round the northern end'of our mountain 

 system, at least as far as Dubbo, and extended far to the north- 

 ward, west of the Sister Island. It formed our eastern coastline 

 running nearly north and south as far as Bateman's Bay, where 

 its record is lost. 



This sea was not generally deep, but had a very rugged bottom ; 

 and there were probably many small islands in it, about which no 

 conglomerate would form, for obvious reasons. Their shores and 

 the general sea floor were formed by corresponding deposits, but 

 composed chiefly of sand, sometimes so full of shells as to become 

 impure limestones. The lime however has by the present time 

 been almost entirely removed by acid percolation, at least in the 

 beds to which we have access. They are known generally as the 

 Upper (Uppermost) Marine Carboniferous series, and are found 

 as evidence of this ancient sea in many parts of our coalfields. 

 They can seldom be traced by their outcrop, because the super- 

 incumbent or fresh water beds (including the coal itself, which 

 is of subaerial formation) for the most part overlap them. Con- 

 sequently they only become visible when disclosed by dislocation 

 and erosion, or when penetrated by miners in sinking for the 

 lower seams. They have thus been proved at Anvil Creek, G-reta 

 and Stony Creek near Maitland, at the Australian Agricultural 

 Company's and the Wallsend pits, Newcastle ; at Mount Keira, 

 near Wollongong ; at Kangaroo Eiver, near its junction with the 

 Shoalhaven, where they are bedded on Grranite, and at Jarvis 

 Bay. They have also been proved further to the west at Xattai, 

 Burragorang, Lithgow, and the Wolgan.* I do not doubt that 

 the level country at the bottom of the Capertee Valley is of the 

 same formation, though I was unable to examine it except from 

 a distance. And there are innumerable localities in the basin of 

 the Hunter, and some at least in that of the Namoi, where they 

 are also found. 



* See reports by Eev. W. B. Clarke and Mr. J. Mackenziej Mines and 

 Mineral Statistics, 1875. 



