342 
Geology of Sydney. 
3. The basements of some of our large buildings 
are Melbourne “ bluestone,” a Tertiary basalt 
with a somewhat vesicular structure, imported 
from Victoria. 
4. The so-called trachyte, from Bowral, is now used 
extensively by architects. The best example of 
its application is seen in the Equitable Buildings, 
near the General Post Office, George-street, where 
this beautiful stone is used in the rough, dressed, 
and also polished. 
5. Granite is mostly used in the form of turned and 
polished columns. The Post Office pillars are 
Moruya granite. Gabo Island granite, of a warm 
flesh tint, is very often made use of for pavements, 
and some polished columns of the same material 
are used in the facade of the Lands Office. 
G. Australian marble is not used extensively about 
Sydney, not from lack of the material however, 
but rather on account of the great cost of trans- 
port and skilled labour. No marbles are known 
on the coast, so that the carriage of marble 
from the interior must always remain somewhat 
prohibitive. 
7. Bricks are made from the clays of the Wianamatta 
Shales, and there is no lack of this material imme- 
diately around Sydney. The shales are a bluish- 
grey colour, the iron present in them being mostly 
in a ferrous condition. Messrs. Bake well Bros, cour- 
teously informed me that at their pottery works, 
St. Peters, near Sydney, they manufacture from 
the Wianamatta Shales such a variety of wares as 
