Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/41

Rh GEOLOGT Of NORTH GIPPSLAOT), VICTORIA.

15

Fig. 4. — Argillaceous and Crystalline Schists near Omeo.

A. Section near the Livingstone Swamp. a. Surface-soil and rubble. b. Glistening nodular argillaceous schists.

c. Quartzite. d. Quartz vein.

Dip about N. 60° E. at 75° to 80°. B. Ground-plan of contact of the argillaceous and crystalline schists from a gully near Livingstone Swamp. a. Granitic schist, b. Nodular argillaceous schist. No well-marked contact can be seen at this place between a and b, excepting at the sides of b, as shown. The nodules are unusually large, being oval and up to a quarter of an inch in length.

In crossing to the eastward, these argillaceous schists are seen to extend beyond the Omeo Plains ; but it is only occasionally that the rocks are visible. They appear to have been much disturbed by the quartz-porphyries "which form the mountains of the Great Dividing Range on the south side of the plains, and are considerably indurated and altered in texture along that line.

In proceeding southward from the plains, a gradual series of changes in the rocks may be traced connecting the argillaceous schists with the indurated slates and sandstones, which end in the granite of Bindi, and which have so completely the appearance and position of the Silurian rocks elsewhere seen to have been invaded by granites, that I have felt little doubt in regarding them as such. I think we may infer that the complete metamorphism which pro- duced the crystalline schists of Omeo has been subsequent to the first alteration of the sedimentary strata into the argillaceous schists.

These latter rocks continue to the eastward for some distance beyond the plains ; but the structure of the country then becomes marked by extensive flats of clay derived from the hills connected with Mount Leinster. In one place a coarse black mica-schist is met with, having a dip to the west of 43°.

Passing still further to the eastward over a tract of country occupied by tho porphyritic rocks of Mount Leinster and by horn- blendic granite, the crystalline schists are again found*. This is at

masses of Mount Leinster ; but, from a few microscopic sections which I have prepared, I conclude that they probably all belong to the class of "por- phyrites."
 * I am at present unable to assign an exact place to the interesting ro?k