68 T. W. E. DAVID. 
interstratified between the top of the Upper Marine Series and 
the base of the Dempsey Beds, which underlie the Newcastle 
coal-measures. The abundance of fossil trees referable to Arau 
carioxylon, many preserved in the form of stumps in situ in the 
formation in which they grew, is clear proof that the conditions 
under which the Newcastle-Bulli coal-measures grew were terres- 
trial rather than marine. The formation of the last of the coal 
seams of the Newcastle-Bulli Series closes the history of the 
Paleozoic era-in New South Wales. 
Triassic time witnessed the deposition of the sediments of the 
Narrabeen Beds, partly lacustrine or estuarine, partly of volcanic 
(tuffaceous) origin. The entire absence of distinct marine fossils 
in these beds, and the abundance of remains of terrestrial plants 
and Hstheria, suggest that the conditions were lacustrine or fluvio- 
marine. The sands and conglomerates of the Hawkesbury Sand- 
stones were next formed under conditions probably similar to those 
just described, but there is no evidence of any important tuffaceous 
beds in this group. The material of which it is formed was derived 
from Plutonic rocks to a considerable extent ; and the currents 
which carried it came chiefly from south-south-west, so that it 
may be inferred that high land lay in that direction. A slight 
elevation appears to have followed, and the clays of the Wiana- 
matta Shales were next formed in a brackish lake of much smaller 
dimensions than the area covered by the Hawkesbury Sandstones. 
The Wianamatta Shales conclude the Triassic system of New 
South Wales. There is no evidence to shew that any strata were 
added to the Blue Mountain area, or the present coastal strip, in 
Jurassic or Lower Cretaceous time. <A slight upward movement, 
however, of the western portion of the Blue Mountains appears to 
have been in progress whereby the upper Marine Beds of Mount 
Lambie were elevated to a height of over 3,500 feet above the sea. 
At the close of the Mesozoic, or commencement of the Tertiary 
era, a large river flowed from south to north at the top of what 
is now Lapstone Hill, so that the erosion of the eastern portion 
of the Blue Mountains could not have fairly commenced at this 
