Page:A sketch of the physical structure of Australia.djvu/37

25 those localities are at a sufficiently low level to admit the waters of the sea.

At Port Stephens, a little north of Hunter's River, are some great hills, and a wide district of porphyry, which has often a syenitic character. Sandstones of the palæozoic formation sometimes are seen leaning on the porphyry at very high angles, and containing in some instances pebbles of the porphyry or some very similar rock; but in others they are traversed by dykes and intrusive masses of a rock almost equally similar. The relative age therefore of the porphyry can only be discovered by a much more detailed survey than I was able to make of the district.

North of Port Stephens, our information becomes very scanty. From "Hodgkinson's Australia," however, we learn that there is sandstone and limestone (probably palæozoic) in the hills between the rivers Hastings and M'Leay. That there is granite, trap, clay, slate, and limestone, at various parts of the M'Leay river, and also in the hills which form part of a great lateral spur that projects from the main chain between the rivers M'Leay and Clarence. We have also in the same work indications of palæozoic rocks between those places and Moreton Bay, and in the latter district we learn