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Geology of Sydney. 
Permo-Carboniferous and Triassic sediments, and are 
now strewn on the surface as silent witnesses of the 
amount of denudation and wear and tear that this 
country has suffered. 
At various points on the road, walls of sandstone 
may he seen away in the distance, across the valleys, 
every wall or cliff showing a slope or talus at its base. 
Fig. VO.- — Halyntes, a characteristic Silurian fossil coral, known as 
“chain coral.” Abundant in limestone near Molong, New 
South Wales, 
On the top of Cave Hill we find diorites and por- 
phyries intruding the Silurian sediments. Many 
examples of these intrusions will be found in the long 
cutting down to the Caves. Almost vertical slates can 
also he noted, dipping now in one direction, now in 
another. A careful examination will show masses of 
