10 JOURNAL OF SCIENCE. 
position and forming the upper portions of the Blue Mountains. 
Further to the north, in Queensland, this system is overlaid in 
places by rocks of jurassic and cretaceous age. Jurassic rocks 
are also found in Tasmania, Victoria, and in Western Australia ; 
consequently we must suppose that during this period Australia 
was more depressed than at present, although not altogether 
submerged. During the whole of the cretaceous period all cen- 
tral Australia and the whole of Queensland appear to have been 
under the ocean, the Rev. J. Tenison-Woods having found upper 
cretaceous rocks on the very summit of the dividing range inland 
from Brisbane. But Western Australia, New South Wales, 
Eastern Victoria and Tasmania remained above water. There 
are no tertiary marine rocks on the east coast of Australia, and 
we must therefore assume that in the eocene period Queensland 
was elevated, and from that time neither it nor New South Wales 
have ever stood much lower than at present. It also appears 
probable that the centre of the continent remained submerged 
until the close of the miocene period, or even later. But the 
geological evidence on this point is at present uncertain, for the 
“Desert Sandstone,” so largely developed in the interior, and 
which lies unconformably on the cretaceous system, is thought 
by Daintree and Clarke to be marine, by Etheridge to be lacus- 
trine, and by Tenison-Woods to be of eolian origin and of 
different ages. Marine miocene rocks are found at an elevation 
of 800 feet above the sea,* but as the central plateau of Australia 
rises to more than 1000 feet in the north, it would not necessarily 
be altogether submerged ; especially as the northern parts of 
Australia appear to have been subsiding for a long time. On the 
other hand Professor Duncan is of opinion that the miocene sea 
of South Australia and Tasmania was of so high a temperature 
that it must have been open to the influx of warm currents from 
the north. Be this as it may, it is evident (1) that during the 
jurassic and cretaceous periods Australia stood at a lower level 
than at present, and (2) that it could not have been joined to 
New Guinea during the cretaceous period as supposed by Mr. 
Wallace, although this may very probably have occurred during 
the eocene period. 
Western Australia appears to have been more stable than 
any other part of the continent. The Darling range consists of 
granite, capped by sedimentary rocks of upper paleeozoic age. 
On the east these ranges end abruptly in cliffs from 200 to 500 
feet high, overlooking plains and salt marshes composed of the 
“desert sandstone.” Towards the sea, on the west, the granite 
disappears and its place is taken by upper palzeozoic rocks, which 
are overlaid in places by another system of undoubtedly jurassic 
age ; and these are again overlaid near the coast by zolian rocks 
of a recent date. Western Australia, therefore, appears to have 
been a land surface during the whole of the tertiary and 
cretaceous periods, and perhaps it may date back to triassic times. 
* C. S. Wilkinson. ‘‘ Notes on the Geology of New South Wales,” 1882, p. 57. 
