Coal Basin of New South Wales. 5 
sandstone. The fossiliferous limestone or its equivalent is at 
this spot shown to be absent, not even the silurian strata 
intervening between the sandstone and the crystalline rocks. 
This fact, taken with the circumstance that limestone forms 
the base of the series in Tasmania, at Newcastle, and at 
Wollongong, goes in some measure to point out the con- 
ditions under which the entire formation came to be 
deposited, viz., that after the laying down of the limestone 
there existed, hereabouts, a gradually sinking sea bottom, | 
since the circumstance that no limestone is found reposing 
upon the granite shows that at the time of the limestone’s for- 
mation the granite must have existed in the form of islands, 
afterwards so far submerged as to allow of a subsequent 
thick layer of sandstone being thrown down upon them. 
I had neither time nor opportunity to explore personally 
these deposits, but what fossils obtained from them were 
shown me in private collections, were found to resemble in 
the most striking manner similar organic remains which | 
had met with near Hobart Town, and consisted for the most 
part of Fenestella Producta, Terebratulide, Conulare, and 
Orthoceratites. I may mention that at Raymond-terrace and 
also at Illawarra Terebratula hastata is mentioned by 
Stezelecki as a common fossil, one which Mr. Geikie, in his 
“Story of a Boulder,” speaks of as occurring at depths of 
not more than 50 fathoms ; here then, if the latter assertion 
is correct, is sumething like reliable data by which the 
maximum depth of the sea hereabouts during the limestone 
era, may be approximately arrived at. 
A paper professing to treat of the geological features of 
the Hartley, Newcastle, and Wollongong districts would be 
manifestly incomplete, if no allusion were made to the 
large deposits of bituminous shale met with in each of these 
localities. That of Hartley is, at present, for the most part 
obtained from one of the valleys of the Blue Mountains, pre- 
viously alluded to, termed Petrolia Vale. The deposit occu- 
pies the very bottom of the slope of the two sides of the 
valley, and probably once extended, if it does not now 
extend, completely across the intervening flat, made up of 
alluvial accumulations. On the western slope it is seen to 
crop out at the surface, and is procured by driving a tunnel 
into the hill side, but on the opposite side of the valley it is 
only reached by means of a shaft some thirty feet in depth. 
The seam here hit upon is of exceeding richness, yielding 
over 160 gallons of crude oil to the ton. In its purest state 
