THE GEELONG NATURALIST. 
elevation is considerably less than this. On either bank there 
is basalt, and it looks as if the river had actually cut this vast 
channel since the outpouring of the lava sheets. I admit, 
however, the possibility of the erosion of the channel, com- 
menced earlier. There are some interesting problems of 
dynamical geology to be solved in the neighbgrhood of Shel- 
ford and at Inverleigh, where the Leigh joins the Barwon. 
The width and depth of the gorges of many Victorian rivers 
have frequently excited astonishment when they are com- 
pared with the insignificant streams which have apparently 
carried them out. Long continued action together with 
changes in the position of the river bed will account for great 
erosion, and to these causes may be added the probable 
gradual rise of the land during a great part of the time. 
Besides the Shelford outcrop, similar fossils can, I am in- 
formed, be obtained in other portions of the Leigh River, as 
the Native Hut Creekis close at hand, and also in the Barwon 
at Inverleigh, Murgheboluc, &c. 
Without doubt therefore the fossiliferous strata are con- 
tinuous over a very wide area at no great depth below the 
surface. The researches of Messrs. Hall and Pritchard, and 
others have shown their existence in the Moorabool Valley ; 
they have been noticed on the Barwon at Birregurra, in the 
road cuttings at Beeac, and as far south as the upper Gelli- 
brand River; while farther west still, at such well- 
known localities as Camperdown, the Lower Gellibrand, 
Muddy Creek, the Glenelg River, &c., similar strata are re- 
corded by many observers. An unbroken section therefore 
might be drawn from Geelong right on to the South Austra- 
lian border and even far beyond, showing strata in 
which the fossils prove to belong to the same horizon. 
In some cases they appear at the surface, though they 
are generally overlain by the Newer Basalt as at Shelford, 
by still later marine tertiaries as at Muddy Creek and on the 
Glenelg, or by recent drifts as at Inverleigh, the Lower Gelli- 
brand, &c. 
They rest upon various older sedimentary and igneous 
rocks. ‘Thus at the Lower Gellibrand, the underlying rock 
is mesozoic ; on the Grange River an ancient porphyry forms 
the base: at Geelong itself similar strata rest on the Older 
(Eocene) basalt ; while as the western boundary of the colony 
is reached, owing to their great increase in thickness, the base 
has not been found, although borings of over 1000 feet deep 
have been made. At Shelford the underlying strata do not 
show, but I am informed on reliable authority that a few miles 
higher up the river the fossil beds lie directly on the Lower 
Silurian. 
12349 
Mm 
& 
e 
ES, 
