26 A. W. HOWITI ON THE PHYSICAL GEOGRAPHY AND 
moved the greater portion of it before the succeeding groups of strata 
were laid down. Denudation had also probably removed much of 
the volcanic materials of Wombargo and other localities of the Snowy- 
River porphyries. I have now to consider those groups of strata, 
which I believe may be classified as above. 
Mr. Selwyn described several groups of strata in North-east 
Gippsland, in the localities of the Avon, Freestone Creek, Iguana 
Creek, and Mount ‘’ambo, as provisionally classified as Upper Paleo- 
zoic, and he regarded the plant-bearing sandstones and conglome- 
rates of Mount Tambo as being below the fossiliferous limestones of 
Bindi, and therefore as ‘‘ older than the true Huropean Paleozoic 
coal-measures ”*, 
I believe that I shall be able to show that this view of the pro- 
bable age of the Mount-Tambo beds is untenable, being based on a 
misconception of the true stratigraphical relations of the Mount- 
Tambo and Bindi formations. At first sight, however, their posi- 
tions appear to be such as are indicated by Mr. Selwyn. 
The groups of strata which until now have collectively been 
spoken of as the Avon Sandstenes have recently been separated into 
two divisions—the Avon Sandstones proper, containing Lepzdoden- 
dron australe, M‘Coy, and referred to the base of the Carboniferous +, 
and the Iguana-Creek beds, with Archeopteris Howitt, M‘Coy, Anez- 
mites iquanensis, M‘Coy, and Cordartes australis, M‘Coy %, and re- 
ferred to the Upper Devonian. 
Still further inquiries have enabled me to extend the Iguana-Creek 
beds northward as far as Tabberabbera, and westward as far as 
Maximilian Creek, thus confining the Avon Sandstone proper within 
much narrower limits than formerly. The exact stratigraphical 
relations of the two groups have not yet been worked out. At 
present I incline to believe that the passage may be gradual from 
one to the other, that is, from the Upper Devonian to the Lower 
Carboniferous, which is not unusual elsewhere. 
I now proceed to describe the Upper Devonian strata from the 
typical locality Iguana Creek, and from which I have named the 
whole group. 
Iguana Creek joins the Mitchell River just within the line where 
the fringing marine Tertiaries thin out on the older rocks. It is 
here that the Iguana-Creek beds are seen to dip at a low angle under- 
neath the Tertiary sands and clays. ‘The base of the series is not 
here visible, the “‘ Lower Paleeozoic formation” having dipped to- 
gether with the overlying strata, so that at the place mentioned, and 
also generally, though not at all places along the same line, it is 
velow the water-level of the rivers. 
* “Notes on the Physical Geography, Geology, and Mineralogy of Victoria,” 
by A. R. C. Selwyn, &c., Intercolonial-Hxhibition Essays, 1866, p. 17. 
+ A.B. C. Selwyn, “ Notes on the Physical Geography, Geology, and Mineralogy 
of Victoria,” &c., Intercolonial-Exhibition Essays, 1866, p. 15; and ‘ Prodromus 
of the Palxontology of Victoria,’ decade i. p. 87, by Frederick M‘Coy, F.G-S., 
Government Palzontologist, &c. 
t ‘Report of Progress, Geological Survey of Victoria,’ No. 2, p. 72. 
