CHAPTER VII. 
THE TRIASSIC ROCKS. 
ORIGIN OF THE NAME — A THREE-FOLD DIVISION — THE 
IIAWKESBURY-WIANAMATTA SERIES — THE SANDSTONES — 
THE SHALES — THE IRONSTONES —THEIR FOSSIL CONTENTS 
THE SANDSTONES AND SHALES BELONG TO THE SAME 
GEOLOGICAL PERIOD. 
The beds known as Triassic are so called from the 
fact that in Germany rocks of Triassic age are made 
up of three distinct groups ; 
1. Keuper or 
Marl group. 
2. Muschelkalk or 
Mussel-chalk. 
3. Bunter or 
Coloured Sandstone 
Curiously enough, the Triassic beds of the coastal 
districts of New South Wales admit of a like three- 
fold grouping. The three groups are : — 
1. Wianamatta Shales. 
2. The Hawkesbury Sandstones. 
3. Narrabeen Shales. 
