78 
Geology of Sydney 
water either by ocean currents or rivers carrying 
along sediments and depositing them in layers, or by 
some chemical reactions, or by the intervention of 
organic life. In tabular form the divisions stand 
thus : — 
j Clay, shale, flagstone. 
I. Sedimentary - Sandstones. 
[Conglomerates. 
II. Organic / Limestones. 
j^Coal. 
( Rock-salt, some limestones. 
Flint. 
Gypsum, &c. 
Rocks 
of Aqueous 
origin. 
Rocks ( T Volcanic, 
of Igneous - 
origin. [ll. Plutonic. 
| Lavas, Basalt, 
( Volcanic Ashes, &c. 
Diorite. 
Granite. 
Metamorphic. 
Rocks of 
Aqueous or 
Igneous origin. 
Marbles. 
Some slates. 
Various kinds of schists. 
Gneiss, &c. 
In the districts referred to in this book the 
following rocks occur : — 
Basalt : Dykes about Sydney. 
Dolerite : at Prospect. 
Basalt : Mount Hay, Mount Tomah, and 
Igneous Rocks 
Mount King George, Bathurst and 
Orange. 
