54 THE HAWKESBURY SANDSTONE. 
well formed crystals. The uppermost beds of this formation, — 
especially where they become conglomerates, exhibit isolated sum-— 
mits, imitating ruined castles, and have thus been ‘traced by me_ 
at intervals all along the escarpments to the westward of Sydney, 
from the latitude of the Clyde River to that of the Talbragar, aul 
in certain localities within the longitude of that line and the cous. 
In the deep ravines of the Grose and Dargan’s Creek, one 
eastward, and the other westward of the Darling Causeway 
versed by the Western Railway line, the slopes are studded with 
fantastic pillars sculptured by denudation and decay into imitative - 
architectural forms. Similar forms cap the extension of the coast | 
range to the head of the Goulburn River. The tints are poikilitie, 
considerable masses of the sandstones could have received nae 
By washing in acids the colouring matter of the particles may og | 
have been instances, as stated to me by the Engineer-in-Chie sa 
the largest blocks have been shisnapd te atoms by a not very hee? : 
fall over an embankment.”—Sedimen. Form, N.S.W- i. 
pp: 70 et seq. ; 
__ Eatent.—The extent of this formation about Sydney 
able. According to the geological map of New South r 
piled Mr. Wilkinson from Mr. Clarke's notes; 16 “lg 
oblong mass about 140 miles long, with a width of from | | i. 
miles, With the exception of a north-western sput whole 
‘harrow range extending 50 miles from the mass, the © ves 
seems to be between two degrees of latitude. A line dra" gf 
ward from Newcastle on the north, ; 
