~~ 
it oi, 
PROCEEDINGS OF SECTION C. 441 
10.—OBSERVATIONS ON THE TERTIARY AND POST- 
TERTIARY GEOLOGY OF SOUTH-WESTERN VIC- 
TORIA. 
By Joun Dennant, F.G.8., F.C.S., Corr. Mem. Roy. Soc., S.A. 
THE region referred to in this paper forms the basin of the 
Glenelg River, and comprises the counties of Follett, Normanby, 
Dundas, and the southern half of Lowan. With the exception 
of Dundas and a small portion of Normanby, it may be described 
generally as an extensive limestone formation, of Tertiary age, 
overlain either by basalt or by drift sands and gravels. In 
places the limestone crops out in ridges, but, when covered by 
the more recent deposits mentioned, it is always found at a short 
distance below the surface, and is thus frequently exposed in the 
channels of creeks and rivers. The Glenelg has for more than a 
hundred miles of its course carved out a deep as well as wide 
gorge through beds of limestone. One is much struck by the 
height of the cliffs on the Glenelg at Dartmoor, and also by their 
great distance apart—that is, by the width of the gorge through 
which the river runs. Not only is this noticeable for the Glenelg, 
but even in the case of insignificant streams, or rather creeks, 
which flow into it. The Glenelg gorge is, at Dartmoor, perhaps 
as much as a mile across, and that formed by the Glenaulin 
Creek nearly half a mile, though it is but a puny stream. The 
actual channel of the Glenelg is much increased in volume during 
winter floods, but even then it never approaches the top of the 
cliffs. From Drik Drik the width, but not the depth, of the 
gorge gradually diminishes, and close to the mouth of the river it 
is only from 100 to 200 yards across. The friable nature of the 
limestone causes it to suffer degradation rapidly when once it 
becomes subject to atmospheric wear, and it is possible that in 
course of time the gorge, even there, may yet widen out from 
this cause alone. If this is the only cause, then at Dartmoor 
and upwards the river must have been flowing a longer time than 
near its mouth. 
From various portions of the strata, I have, during the last 
few years, collected nearly a thousand species of fossils, the 
majority of which have been determined by Professor Tate. 
With their aid, and by noting the relative positions of the beds, 
the Tertiaries and Post-Tertiaries of the district can be classitied 
into several well defined groups, which will be discussed in the 
order of their deposition, beginning with the lowest. 
I.—Lower TERTIARY. 
As the celebrated shell beds at Muddy Creek have been 
described by me quite recently, the remarks now made upon them 
