1856.] WILSON AUSTRALIA. 285 



portion is so hard that it resists the action of the water with greater 

 firmness than the trap-dyke itself to which it seems united. 



The upper seam of coal, where it comes in contact with the dyke, 

 has been altered in the same manner ; but the alteration extends 

 only a few feet on each side. A similar dyke passes through Beacon 

 Hill, where I saw a number of prisoners working a seam only a few 

 feet from the dyke, to obtain coal for the Beacon-fire. 



At the top of the island, on the south side, the rocks have parted 

 from the dyke to the extent of about one inch, and the space has 

 been filled with clay and gravel, washed in from the shale and con- 

 glomerate above, as far down as the first coal-seam. This mixture 

 is highly impregnated with the oxide of some metal (supposed by 

 Mr. Stutchbury to be nickel), and is of a yellowish-green colour. 

 Nobby's Island is about 100 feet high ; but the top, as far down as 

 the first coal-seam, is being cut down to form a level base for the 

 erection of a light-house. 



At a promontory called Red Head, six miles southward from 

 Newcastle, Mr. Beaumont showed me the remains of a fossil forest 

 on a broad bed of shale that was generally covered at high-water. 

 Roots of trees, evidently in the situation where they had grown, now 

 consist of rich ironstone. Some of the trees, broken off by the roots, 

 and lying in the place where they first fell, are similarly fossilized. 

 Some of the trunks are about 2 feet in diameter. 



At a place three miles nearer to Newcastle, several tree-trunks, of 

 more than one kind, are exposed to view, all of which consist of iron- 

 stone. Near the same place, in the face of the clifP, but in several 

 beds higher in the series, a part of the trunk of a fossil tree, about 

 4 feet in length and 1 in diameter, stands erect in a bed of decom- 

 posed shale ; but this tree has nothing of the ferruginous character 

 of the trees of the lower bed. 



In crossing the range of hills between Maitland and Singleton, I 

 met first with a porphyritic dyke, containing fragments of quartz 

 and crystals of felspar ; next was a shelly limestone, corresponding 

 to the mountain-limestone ; and afterwards a hard conglomerate, 

 at a cutting west of the point where the Black Creek crosses the 

 road. It is of a bluish colour, and contains marine shells and water- 

 worn pebbles of the crystalline rocks. 



From six to eight miles N.W. from Singleton are large quantities 

 of angular ironstone-gravel, without any appearance of having been 

 waterworn ; and soon afterwards I found the source from which it 

 had descended, — namely, the remains of a fossil forest, similar to 

 that on the coast at Redhead. One large stem, that lay extended 

 from a wide-spreading root from which it had fallen, measured 

 12 feet in length. It appeared to me, that the rock in which these 

 trees are imbedded is the same in age as that containing similar 

 fossils at the water's edge near Newcastle. 



About five miles from Muswell Brook I saw an edge of old slate- 



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