SYDNEY SANDSTONE. 459 
mountain just beyond, we soon reach the Sydney sandstone, which 
continues to the summit, where it stretches far to the northward and 
westward in a gently inclined plane, though broken in many parts by 
EAST AND WEST SECTION THROUGH ILLAWARRA, FROM WOLLONGONG. 
deep valleys or gorges. ‘The several deposits are conformable, and 
constitute an unbroken series. Similar sections, including the coal 
and the Sydney sandstone, are in view near Newcastle ; and at Green- 
hills, seventeen miles west, there is an argillaceous sandstone abound- 
ing in fossils, apparently identical in age with that of Wollongong. 
II. SYDNEY SANDSTONE FORMATION. 
Geographical Extent.—The Sydney sandstone is the prevailing rock 
of New South Wales, and probably, as Major Mitchell states, of all 
New Holland. It extends from Shoalhaven River on the south to the 
Hunter River on the north, and west some distance over the Dividing 
range, only occasionally interrupted by basalt or granite, or the out- 
cropping inferior deposits. North of the Hunter it occupies many 
valleys as far up as the Liverpool range of mountains. Beyond these 
mountains, itis said by Major Mitchell to occur again on the Nammoy 
and the head waters of the Darling; west of the Dividing range it 
does not appear to predominate until approaching the valley of the 
Darling, three hundred miles or more in the interior, where a similar 
rock is described as common. ‘These few facts may give some idea 
of the sameness that characterizes the geology of New South Wales. 
The thickness of the sandstone above the coal may be deduced 
approximately from the elevation of the Illawarra heights, and the 
altitude of the main range of the Blue Mountains. The former vary 
from eight hundred to eighteen hundred feet, and consist at base 
of the coal layers; and if four hundred feet be allowed for the 
subjacent deposits, we have fourteen hundred for the Sydney sand- 
stone. Nearly the same thickness may be inferred from the sections 
observed in the Blue range. North, towards the Liverpool range, 
