80 
Geology of Sydney. 
A MORE COMPLETE LIST OF ROCKS OF 
AQUEOUS ORIGIN IS AS FOLLOWS:— 
List of Mechanically Foemed Rocks. 
{ Gravel and Rubble when loose ; Con- 
glomerate and Breccia when compacted. 
Sand and Silt when loose; Sandstone, Flag- 
stone and Gritstone when compacted. 
Argillaceous f Mud, Clay, Marl, and Loam when soft ; 
op -| Shale, Mudstone, Clay-rock and Slate 
Clayey. I when indurated. 
Arenaceous 
or 
Sandy. 
List of Organically Formed Rocks. 
Carbonaceous. { Peat, Lignite, Coal, Anthracite, Graphite. 
Calcareous 
or 
Lime-bearing. 
Limestone and its varieties — Compact, 
Crystalline, Chalky, Oolitic, some 
Dolomites, and Globigerina ooze. 
Siliceous or ( Radiolarian rocks, Chert and Diato- 
Quartz-bearing. { maceous rocks. 
List of Chemically Formed Rocks. 
Siliceous. (Flint, Chert , 1 Sinter. 
( Travertine, Stalactites, Stalagmite, Cal- 
Caleareous. \ _ , 
( careous nodules, and concretions. 
1 Fine-grained argillaceous sedimentary rocks occurring in the Coal-Measures 
are sometimes called cherts. 
