HaWKESBURY- W I AN AM ATT A. 
189 
the wind over limited areas. Altogether the great 
Triassic lake at one time might be compared to a vast 
morass or swamp. Again it showed deeper water, 
with swift currents and turbid rivers rushing down 
as torrents laden with sand, to build up the sandstones. 
Once again we see the morass condition repeated, 
while the Wianamatta Shales were forming. 
Rocks of the same age in Europe yield brine 
springs, and are the great source of the supply of 
common salt. The European Trias was also deposited 
in and around an inland lake or shallow sea, whoso 
waters were charged with salt and gypsum. The con- 
ditions were not unlike those around the Dead Sea of 
the present time. The middle division — the Muscliel- 
kalk, a shelly marine limestone — shows that there was 
a great ingress of sea-water, or perhaps the lake may 
have become an open sea. Anyhow, the fossils tell us 
that there was an abundance of marine life. No 
such episode characterised the Trias in England or 
Austral ia. 
As to when the Hawkosbury-Wianamatta rocks 
were deposited, there is not much to learn. The series 
is newer than the Coal Measures, and older than the 
Cretaceous rocks of the north-west of New South 
Wales. No better illustration can be given of the 
vast antiquity of these geologically-speaking modern 
rocks, than a reference to the stupendous changes 
that have taken place since their deposition. 
Towards the close of the Mesozoic period, and 
during the Tertiary period, physical, climatic and 
