242 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 24, 



ing a tract of country two or three miles wide, to the southward of 

 which again were other sandstones of a dull red colour ; but our time 

 did not permit of our working out their relations with any approach 

 to accuracy. I will now briefly describe this section in an ascending 

 order, and glance at the extension of the rocks over the adjoining 

 district, and at the position in which they now repose. 



5. The lowest group of rocks, the Wollongong sandstones, are 

 commonly thick-bedded, fine-grained, and either dark grey or reddish 

 brown. They are often slightly calcareous, and contain many concre- 

 tionary calcareous nodules, from two inches to two feet in diameter, 

 which when broken open commonly disclose a fossil shell. Beds two or 

 three feet in thickness often exhibit concentric bands of colour, or sec- 

 tions of spheroidal coats, and the rock has more or less a tendency to 

 decompose along these coloured coats. This concretionary structure 

 in one place exhibited itself on a much larger scale. A portion of the 

 beds, twenty feet high by thirty feet long, and consisting of six or eight 

 beds, exposed in the face of a cliff, showed on each side the coloured 

 edges of concentric coats enveloping the whole mass. The lines of 

 lamination of the beds passed through the enveloping coats without 

 alteration. The coats were not more than a foot thick altogether, 

 and peeled off as they decomposed, leaving the mass described above 

 as a solid nucleus. 



These Wollongong sandstones contained a few fragments of fossil 

 wood and shells and corals, identified by our Curator Mr. Sowerby. 



Fossils of Wollongong. 



Stenopora crinita. Pachydomus ovalis (P. globosus, Morris, 

 Producta rugata. not Sowerby). 



Spirifer subradiatus. Orthonota, sp. nov. 



Stokesii. Pleurotomaria Strzeleckiana. 



avicula. Bellerophon contractus, MSS., sp. nov. 



Pachydomus carinatus. 



At Wollongong these beds dipped to the N. and N.N.W. at a 

 slight angle, and in following them along the coast in that direction, 

 as we rose on to the higher beds and approached the coal, the sand- 

 stone became charged with great quantities of fossil wood. In the 

 level sheets of rock left by the tide at low water, great fragments of 

 black fossil wood, with smaller chips scattered about, were exposed 

 in the lighter-coloured sandstones, with their edges rounded and worn, 

 and having been evidently drift-wood before they were enclosed in the 

 rock. So like were they to common drift-wood on a beach, that I 

 could hardly help fancying them so, until their hard siliceous sub- 

 stance and the difiiculty of extracting them from the sandstones 

 proved the contrary. The total thickness of these sandstones, as 

 seen by us, was about 300 or 400 feet. 



4. The coal-measures that show themselves in the cliffs, on the 

 north part of the lUawarra district, are but very insignificant, the total 

 thickness of the whole beds containing the coal not exceeding 200 

 feet. The actual thickness of the coal-seams themselves we did not 

 ascertain, but from all we saw and heard of them, they must be but 



