Devonian. 
215 
from Rydal to beyond the Canoblas, while another 
expanse of the same waters spread from Cobar, across 
by Wilcannia, to and beyond the White Cliffs opal 
field. The sandstones about Eden and Twofold Bay 
are of a similar age, and, as shown by Mr. Carrie, of 
the Geological Survey, were laid down under marine 
conditions, RhyucIionelUi plcu/rodou (Fig. 57) being 
found at Bellbird Creek, three miles north of Eden. 1 
Devonian rocks of fresh-water origin have also 
been described by Mr. Carne. They occupy a consider- 
able area in the Nungatta and Yambulla Ranges, 
towards the head of the Genoa River, and contain the 
interesting ferns Archceopteris Howitti and Sphenop- 
teris Garnei, as well as the gymnosperm Oordaites 
Australis. The Devonian rocks on the Blue Moun- 
tains are, however, for the most part marine, but not 
of deep-sea origin. In fact, the abundance of con- 
glomerates and rounded pebbles points unmistakably 
to shore deposits. The Devonian beds have been 
invaded, tilted, and altered by intrusions of granite 
and felsites, some of these last representing what are 
probably the oldest volcanic flows of New South 
Wales. The Devonian sediments, hardened and altered 
to quartzites, have, since their deposition, participated 
in many great earth movements. They are now often 
several thousand feet above sea-level, and tilted for 
the most part from their original horizontal position, 
they have not, however, been folded and compressed 
as intensely as the underlying Silurian Slates. 
1 J. E. Carne, Ann. Kep. Dept. Mines, N.S.W., 1387, p. 163. 
