160 — &. ETHERIDGE, T. W. E. DAVID, AND J. W. GRIMSHAW. 
this may be, that, as indicated by phenomena before pointed out 
by me, but which on this occasion cannot be further dwelt upon, 
the eastern extension of Australia has been probably cut off by a 
general sinking, in accordance with the general Barrier Reef 
theory of Mr. Darwin.” 
Perhaps the most important statement on this subject is that 
made by Mr. C. 8. Wilkinson, the late Government Geologist of 
New South Wales. He says,! with reference to Port Hacking, 
near Sydney :—‘ It will thus be seen that this locality is over a 
very deep portion of the coal basin. The eastern portion of this 
basin has been apparently faulted and thrown down beneath the 
waters of the Pacific Ocean, the precipitous coast, and a line about 
twenty miles east from it, marking approximately the lines of 
dislocation. The deep soundings immediately beyond this would 
seem to favour this view, so that here the bed of the ocean prob- 
ably consists of the old land surface which once formed the con- 
tinuation of that upon which the City of Sydney now stands, and 
which has been faulted to a depth of over 12,000 feet ; the length 
of the faulted area is not known, but it probably does not extend 
along the coast beyond, if so far as, the north and south limits of 
the Colony.” 
“The abrupt eastern margin of the Blue Mountains, up which 
the Great Western Railway ascends at Lapstone Hill, near Emu 
Plains, marks the site of a similar though not so extensive fault, by 
which all the country between it and the coast was thrown down 
to its present level—the depression being so great that the ocean 
water flowed into the old river valleys, one of which forms the 
beautiful harbour of Port Jackson. We have evidence that these 
faultings probably 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 
1 Mineral Products of New South Wales etc., p. 52. By Authority, 
Sydney, 1882. 
