Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/413

 the upper parts of the series, is rare ; it contains there an abundance of Polyzoa, and is a deep-sea deposit. It would appear that this limestone, so well displayed under the basalt of Mount Gambier, to the west of the south-western boundary of "Victoria, is better developed where it is most remote from the high Palaeozoic land, in Central Victoria, and that its position in the tertiary scale is occupied, near to that origin of muddy and sandy sediments, by clays containing more or less of the latter. The upper series of Mount Gambier, called by the Rev. Mr. Woods the " Coralline crag," may be recognized at Cape Otway and in Mr. Daintree's section. In both of these localities the limestone, which closely resembles the white chalk at Mount Gambier, is impure and very much mixed with sediment and some volcanic ash. Other limestones are found low down in the fossiliferous series, and often form masses like islands in a mass of basalt ; but I have not had any fossils from them.

The most fossiliferous parts of the series are yellow and brown ferruginous clays, and dark slate-coloured bands more or less sandy.

In the Cape-Otway series there is a plant-bed containing evergreen leaves, of species not belonging to the existing flora ; it is sufficiently developed to lead to the belief that a temporary upheaval must have occurred, followed by a long subsidence. The deposits which collected during this subsidence resemble those of the upper part of every section of the Tertiaries. They bear witness to the action of currents, to the influx of mud and sand, lava, and volcanic ash, and prove not only that volcanic phenomena were very active close by, but that the older rocks which formed the shore to the north-east were suffering tremendous denudation.

Vast developments of clays with fossil leaves, gravels, and conglomerates were proceeding on the area of the Silurian rocks, which formed the shore and land washed by the tertiary sea, whilst the marine deposits were forming. Even at the altitude of 4000 feet water-worn gravels and boulders were collecting, in some places to the depth of 300 feet. This old gravel, resting on the worn surfaces of the Silurian rocks, is covered in many places by a basalt, whose representative is low down in the marine series on the coast and frequently forms its base.

An immense district, extending from Port Phillip to the river Glenelg, is covered with a basalt which is younger than that just mentioned. It was poured forth over the clays and marls of which the Hamilton beds are the type ; and it covered the littoral and moderately deep-sea deposits which were in-shore of the deep sea, forming the chalky sediment. Mr. Woods has described its position in relation to the fossiliferous beds of Hamilton. Still later, and when these deep-sea deposits had crept over much of the subsiding in-shore series, which had or had not been covered with the basalt, another and long - continued lava -stream, accompanied by ash, poured from the Mount-Gambier district and many of the formerly active vents in Victoria. It covered up the coralline rocks, as they are called, and mixed with and included the lacustrine and river- sediments then forming ; and it probably continued to flow until