Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/65

Rh products seem to be interstratified with aqueous beds. The remains of land-plants, the lithological characters and peculiarities of structure of the beds, perhaps even the prevailing red colour of all the groups of this age (Upper Devonian), suggest to me the possibility that we may have here lacustrine rather than marine conditions, following the gradual emergence of land from the deep-sea areas of Middle Devonian periods, and, if so, yielding another singular parallel to observations made in Europe and remarked upon by Professor Ramsay.

The evidence, so far as it goes, suggests that volcanic activity may have become dormant in the east while it became active in the west, and also, as seen at the Snowy Bluff, that the volcanic materials changed from an acid to a basic character.

A consideration of all the localities where I know strata to occur, which may not unreasonably be referred to the Upper Devonian group, of which the Iguana-Creek beds are the type, has led me to believe that, at the commencement of the deposition of those strata, denudation had almost proceeded to the extent which it has again gained. This may be seen at Mount Taylor, Tabberabbera, the Snowy Bluff, Cowombat, the Native-Dog Creek, and the Gibbo River.

I have at present no evidence to advance as to the condition or the position of the Upper Devonian land.

Future inquiries may possibly throw light on this obscure question; and I look forward with some slight hope to an examination of the great and almost unknown mass of mountains between the sources of the Mitchell and Macallister Rivers, whose dark gorges may possibly yield as grand and instructive natural sections as the deep defiles of the Snowy River have done.

Neither is there any light as to the conditions of what is now North Gippsland during all the long ages succeeding the Devonian until Tertiary times. The Avon Sandstones only show us that they were similar to those under which the Iguana-Creek beds were laid down.

The denuding agencies which have removed the enormous thickness of the Avon and Iguana-Creek groups may certainly have at the same time stripped off superior and younger formations; but, on the other hand, it is worthy of consideration that nowhere, so far as I know, have even traces of any strata of marine origin younger than Carboniferous been met with in the mountains of Eastern Victoria above the height of 2000 feet, or, excluding the Mesozoic Coal-measures, above the height of 1000 feet from the sea-level.

Passing over the question whether the Mesozoic Carbonaceous rocks of South Gippsland ever extended over the whole, or even over the greater part, of North Gippsland, as it is evident the Upper Devonian and, perhaps, the Carboniferous formations once did, I may point out that all the groups of marine strata of Tertiary age