460 NEW SOUTH WALES. 
which is apparently away from the centre of the region of sand 
depositions, the thickness is but four hundred or four hundred and 
fifty feet; below this, coal layers occur. Approaching Newcastle, at 
the mouth of the Hunter, the sandstone becomes very thin, and at the 
cliffs is represented only by a single layer of conglomerate, of which 
we shall speak particularly when describing the coal deposits of New- 
castle. As this conglomerate appears to belong to the upper portion 
of the Sydney sandstone series, it is probable that it presents us with 
nearly the whole thickness which the sandstone has ever had in the 
vicinity of Newcastle. 
Lithological Characters and Stratification —The sandstone of this 
formation is mostly a soft friable rock, of fine texture and light sandy 
colour. It consists of minute grains of quartz, with particles of decom- 
posed feldspar of an opaque white colour, and scales of light-coloured 
mica. The quartz usually predominates. The mica is at times want- 
ing, though small scales may generally be detected; in some cases it 
is so abundant as to increase much the glistening lustre of the rock. 
The colours of the layers are white, grayish-white, and yellowish, 
like ordinary sand ; also varying to light blue and grayish-blue, which 
characterize a variety used as a building material at Paramatta, where 
it occurs. ‘There are also reddish shades. The colours are very often 
arranged in curved parallel bands, or waving lines, and concentric 
oval figures. A very pretty variety occurs to the south, at a place 
called the Cowpastures. Owing to the delicate arrangement of 
the layers of deposition, and the dissemination of mica scales in 
patches, the slabs, which are of a grayish colour, are marked with 
short waves or curls of a darker tint. 
The finer varieties of the sandstone contain an occasional rolled 
pebble of milk-white quartz, three-fourths of an inch to an inch in dia- 
meter; now and then, small fragments of an argillaceous schistose rock, 
either white or some light shade of colour; and rarely black siliceous 
pebbles. Small masses of soft clay of a dirt-brown colour are occa- 
sionally met with imbedded in the sandstone, and some are several 
inches long, though generally small. They are much like lumps of 
clay, and may be kneaded by the fingers when moist. 
Besides the ingredients already enumerated, minute scales of gra- 
phite are found disseminated through a large portion of the rock, like 
the scales of mica. Iron ore in the form of sand is common, and it 
also occurs in seams. The disseminated iron is so abundant in some 
parts that exposure to the air and moisture soon rusts or reddens the 
