Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/456

 lian coral fauna and that of the Tertiaries would give a much older geological age to them than is warranted by the physical geology of the area. During the deposition of the Tertiaries there was much disturbance in the currents and constant alterations in the depth of the coralliferous sea, whose bottom and shores were formed by the Silurians, old basalts, and carbonaceous sandstones of Victoria. The conglomerates and pebbly sandstones were of course formed during different marine conditions from those which existed during the deposition of the clays and clayey sands. As the depth increased during the subsidences which evidently followed every basaltic outpouring, the calcareous element mingled with the wash down from the land, and finally it increased to such an extent that it encroached upon the area formerly occupied by littoral deposits, and even in some places covered the rocks whose denudation had produced the conglomerates.

There were temporary upheavals during this general subsidence ; and the leaf-beds, with, their associated clays, bear testimony to them. The relations of leaf-beds, clays, gypsum, and basic sulphate of iron, so frequently observed in Europe, are repeated in the Australian deposits. The metamorphosis of some of the original contents of these vegetable-bearing clays into gypsum, and the gradual solution of the latter by the natural- drainage waters, may account for the irregular bedding of the Cape-Otway fossiliferous Tertiaries, contortion following the depression incident upon the gradual removal of the salt of lime. The tertiary deposits were not subjected to any other alterations in their relative level than those of the most local kind. There were none of the phenomena of uptilting and crumpling which occurred in the tertiary deposits of the West Indies, Southern Europe, and Sindh ; and one fauna did not collect around the ruins of those which had been antecedent to it.

It is reasonable to admit, especially when the long duration of the time which was occupied by the formation of the series over the fossiliferous deposits is considered, that whilst the vast central area of Australia was a sea, there was open water to the north, with reefs in the Java district and corresponding formations opening into what is now the Mediterranean and the Sahara to the north-west. The Indian peninsula, and the area now occupied by the Himalayas and stretching far away to the east, were not part of a great continent ; and their marine tracts equalled the terrestrial in magnitude. The greater part of the American continent was submerged, and the Caribbean sea was a coral area. Where was the bulk of the land when the coral-sea stretched round the tropics? It could only have been to the extreme north and south. New Zealand and South Australia were therefore bounded to the north by a coral-sea, and to the south by the deep ocean, as now. So far as the coral-fauna is considered, this separation of the Australian sea from the European area by a coral tract inhabited by a distinct fauna, which could only exist under conditions very diverse from those witnessed in Victoria, is explanatory of the comparative isolation of the remote assemblages of species, supposing them to have existed during the same geolo-