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Geology of Sydney. 
here exhibited. This kind of view to me was quite 
novel and extremely magnificent.” 
The Rev. W. B. Clarke thus describes the 
Hawkesbury Sandstones : — “Over the uppermost work- 
able Coal Measures, which are of considerable thick- 
ness, is deposited a series of beds of sandstone, shale, 
and conglomerate, oftentimes concretionary in structure 
and very thick-bedded, varying in composition, with 
occasional false bedding, deeply excavated, and so 
forming deep ravines with lofty escarpments, to the 
upper part of which series I have given the name of 
Hawkesbury rocks, owing to their great development 
along the course of the river-basin of that name. 
These beds are not less in some places than 'from 800 
to 1,000 feet in thickness, containing patches of shale 
occasionally with fishes, with fragments of fronds and 
stems of ferns, a few pebbles of porphyry, granite, 
mica, and other quartziferous slates, and assume in 
surface outline the appearance of granite, from the 
materials of which and associated old deposits they 
must in part have been derived.” 
The Shales. 
The shale-beds of tire Hawkesbury- Wianamatta 
Series are much in evidence about Sydney, if only for 
their economic importance. Brick and pottery works 
make a large industry, materials for which are entirely 
derived from the Wianamatta Shales. It must not be 
forgotten, though, that shales occur at various levels.. 
