69 
Geological History in Palcvozoic Times. 
•which would naturally have included the layers of a more con- 
glomeratic character, have been entirely removed. If the patch 
at Wild Duck Creek, near Heathcote, is correctly classed as 
Upper Palaeozoic — of which there is some doubt — deposits of that 
a g e mus t have flanked the northern slopes of the older rocks, and 
overlaid a large portion of the area now occupied by the Murray 
tertiaries. 
The rocks of the eastern Upper Palaeozoic area show evidence 
of different conditions in their deposit from those observable in 
the Grampian Sandstones. 
Taken as a whole, the bolt of rocks from Iguana Creek to 
Mansfield occupies a deep trough, or long indentation in the older 
rocks, which constitute its margins on the west, north, and east 
The head of the indentation appears to bo represented by the Mans- 
field valley, and if so the Main Divide of the Upper Palaeozoic 
period was further north than the present one, and probably 
in the position now occupied by the Strathbogie Ranges. This 
will be further referred to during description of the Tertiary forma- 
tions. The deposit of the Upper Palaeozoic rocks in this district 
was restricted latterly within comparatively narrow limits ; the 
proximity of the land surface on either side is evidenced by the 
coarse breccia-conglomerates along the edges, and the character of 
the plant impressions discovered in somo of the beds. While they 
were being laid down, the boundary Silurian and granite rocks y 
which formed the land surface, evidently reached a very much 
greater elevation than at present, and projected above the sea. 
There would also appear to have been two distinct volcanic 
districts now represented by the most elevated parts of the Upper 
Palaeozoic belt — one in the country lying between the Jamieson 
and King Rivers, north of the Main Divide, and another ou the 
south, between the heads of the Wonnangatta and the lower part 
of the Macalister, as the upper portion of the latter river appears 
to contain in its bed no rolled fragments of igneous rock that have 
come from the direction of the Main Divide, nor do such rocks 
appear in situ far to the north of the Wellington Range in thp 
Macalister drainage-area. 
The general geological appearances suggest the idea that, at the 
commencement of the Upper Devonian period, a deep fiord or 
sound, between very lofty and precipitous mountain ranges, ex- 
tended inland from the Southern Ocean to what arc now the 
southern bases of the Strathbogie Ranges ; the axial line of the 
western range was approximately from the Strathbogie Ranges to 
Wilson’s Promontory, and that of ibe eastern from the Strath- 
bogie Ranges to between Bairnsdale and the Snowy River. 
The tongue of the Upper Palaeozoic rocks, formed by the ex- 
tension of the Iguana Creek beds in the Mitchell valley up to 
Tabberabbera, seems to represent a minor inlet on one side of 
where the great fiord debouched on the open ocean. 
