Origin or Shales. 
113 
known are for the most part plants — land plants, or 
such as would grow in lagoons or marshy places. The 
magnificent fronds of Thinnfeldia found in the sand- 
stones could never have been drifted very far, and 
must have grown quite close to were the fossil 
imprints are found. Of course, fish remains have also 
been discovered, but they are such as might easily 
have lived in brackish or estuarine waters. The late 
Rev. J. E. Tenison- Woods at one time held that the 
sandstones were all of .dioliau origin, but in later 
years he abandoned that theory. From my stand- 
point, there seems to be no room for doubt that the 
Hawkesbury Sandstones were for the most part laid 
down under water. At the same time, there are minor 
features which are strongly suggestive of the sands 
being subjected to the action of wind previous to 
consolidation. There is presumptive evidence, too, 
that the sand might have been re-distributed and 
bedded by wind over small areas. 
No one doubts but that the shales wero laid down 
in water — in shallow lakes or lagoons. These lakes 
must, it goes without saying, have been surrounded by 
dry land. Now, beds of shale are found at different 
levels in the sandstones, and, therefore, wero formed 
at various levels, as the sandstones themselves were 
formed. Evidently, then, the still unconsolidated 
sands formed the dry land surrounding the lagoons. 
Under these conditions, it is more than probable that 
sand-dunes were formed locally. A general depression 
of the land was in progress, and the shales already 
