320 
Geology of Sydney. 
5. In Carboniferous times sedimentary rocks 
were deposited away to the North of Newcastle and 
Maitland, and probably much of the Devonian strata 
was removed by erosion and denudation, to supply 
the required materials. The Permo-Carboniferous 
and Carboniferous are also unconformable. 
6. The conditions during the Permo-Carboni- 
ferous age shows the area from Moruya to Port 
Stephens and west to Mount Lambie, as a great plain, 
and in part a morass, well watered and clothed with 
a rich vegetation. Periodic inundations submerged 
large areas at a time. A slow, but continuous subsi- 
dence was in progress, that permitted the accumu- 
lation of the great thickness of the Coal Measures 
and associated rocks. The sea during two prolonged 
periods occupied a great part of the whole of the area, 
giving rise to our Upper and Lower Marine. About 
the close of the Permo-Carboniferous great changes, 
widespread in their effect, took place. This region 
was not again depressed beneath the sea, and prac- 
tically all the animals and plants became extinct, 
giving rise to a totally new fauna and flora. 
7. The Mesozoic days witnessed the Hawkesbury- 
Wianamatta series being laid down, under physical 
conditions similar to the fresh-water strata of the 
Permo-Carboniferous. The land was still subsiding. 
8. The next step in the building of the mountains 
was the elevation of the whole region, together with 
a wide strip of land at present covered by the waters 
of the Pacific. 
