614 
This submergence, in all probability, took place after the period to which the 
Extinct Mammalia belonged. It is probably the same submergence to which the late 
Rev. ,T. E. Tenison Woods attributed* * * § the formation of Sydney Harbour. I am quite 
in accprd with Mr. Woods on this point, as the harbour has all the appearance of a 
submerged land valley. 
The late Mr. C. S. Wilkinson ascribed f the depression which created Sydney 
Harbour to certain faults which divide the tableland of the Blue Mountains from the 
low-lying coast country, arguing that the faulting took place towards the close of the 
Tertiary Epoch, “ for no marine Tertiary deposits are known along this portion of the 
coast of Australia, whereas in New Guinea on the north, and in Victoria on the south, 
the marine Miocene beds occur at elevations up to eight hundred feet above the sea. 
Had this low-lying country along the East coast of Australia then existed, it must have 
been covered by the Miocene sea, and doubtless some traces of the marine strata of that 
period would have escaped denudation and remained, as those have which are seen in 
Victoria and elsewhere ; but it is very probable that until or during the Pliocene period 
it stood above the sea-level and extended some distance beyond the present coast line. 
Then, again, the Tertiary deposits throughout East Australia show that the valleys 
draining the Great Dividing Range have been chiefly eroded since the Miocene period, 
for we find deep valleys and ravines cutting through later Tertiary formations ; there- 
fore the sinking of the land traversed by any of these valleys — such as that of Port 
J acksou — evidently took place in comparatively recent geological times, and may have 
been contemporaneous with the extensive volcanic eruptions of the Upper Pliocene 
period during which the southern portion of Victoria especially was the locale of great 
volcanic activity.” 
I regret that I cannot agree with the reasoning of my lamented friend, so far as 
regards the age of the faults in question. All that is certain on this point is that the 
faidting took place at a period subsequent to the deposition of the strata which they 
disturb, as no strata of later date are superimposed on the faults themselves. There is 
no evidence that a low-lying country was immediately produced on the down-tlirow sides 
of the faults. The country east of the faults may have remained during Miocene times 
at a level high enough to be above the reach of the Miocene sea, and may have only 
since then been reduced by sub-aerial denudation to the present level. The argument 
from “deep valleys and ravines cutting through later Tertiary formations ” fixes the 
oldest possible, but by no means the newest possible date for the depression of the land 
surface resulting in the formation of Port Jackson. 
It need excite no surprise that the same Geologist who denied that the Desert 
Sandstone had been laid down at a lower level than that at which it is now found refused 
to admit that “ one well-recorded observation has been brought forward ” in proof of 
recent elevation on the Eastern coast. J Nevertheless, there are several observations on 
this point which must be treated with respect. 
Near Cape York, Dr. Alexr. Rattray, Surgeon, R.N.,noted§ several circumstances 
which prove that Raine Island has in Recent and even in modern times risen from its 
former position. He says : — 
“ Raine Island, which possesses its own special and active fringing reef, is low, flat, 
about one-third of a mile long, and a quarter of a mile broad. It rises about ten feet above 
* Journ. R. Soe. iV. S. Wales, 1882-1883, xvi., p. .53. The Hawkesbury Sandstone. 
tNotea on the Geology of New South Wales. 2nd. Edition, p. 70. Sydney : by Authority : 1887. 
+ Rev. J, E. Tenison Woods. Geology of Northern Queensland. Trans. Queensland Philosophical 
Society, 20th December, 1880. 
§ Notes on the Geology of Cape York Peninsula. Quart. Journ. Geol. Soc., xxv. (1869), p. 303. 
