FOSSILS. AQ 
Fossils of the Sandstone below the Coal, and Age of the Deposits. 
Fossil shells, along with some corals, occur at many localities of the 
argillaceous sandstone. They abound at Wollongong Point, and at 
various points on the shore, to Black Head and Shoalhaven. At 
Wollongong the specimens usually occupy the interior of globular 
concretions, and some of these imbedded bivalves are eight inches long. 
At Black Head, and also between this place and Rocky Cove, and 
three miles south of Kiama, they are scattered through the rock, in 
great numbers. Harper’s Hill and Glendon are localities on the 
Hunter already somewhat noted in the colony. 
The shells throughout the formation are well preserved, the valves 
are united with unbroken edges or angles, (except from pressure,) and 
the ridges or markings are distinct and apparently unworn. The 
bivalves usually lie with the valves somewhat gaping, though some- 
times closed. Numbers of the same species are often clustered 
together. 
The shells are fossilized either with lime or silica. ‘The former is 
the case at Harper’s Hill; and the shells look as fresh and white, and 
as natural, as if just from the water. ‘They are so neatly preserved, 
that, judging from this character alone, they might easily be mistaken 
for fossils of a modern date. When broken across, a cleavage struc- 
ture is often exposed, showing that the original lime of the shell has 
been recrystallized. If, as the writer has suggested in another place, 
the lime of shells is in the condition of arragonite, we may understand 
how a molecular change should take place, producing the ordinary 
calc spar and its cleavage. The stri# or markings of the original 
shell are perfectly retained. 
The fossils of Black Head are either calcareous or siliceous. They 
sometimes consist of chalcedony, with the interior more or less per- 
fectly filled with cale spar. 
The remains of plants are few in number, and are badly preserved. 
Flattened fragments of trees, like those of the coal series, are occasion- 
ally met with. At Black Head, a portion of a silicified trunk of a 
tree, seven inches in diameter, projects three feet from the face of the 
cliff. The structure of the wood was beautifully preserved, and re- 
sembled that of the layers above. ‘There are also coaly impressions 
of irregular form and large size, one of which measures twenty 
inches by six. They present no traces of their original structure ; 
