Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/48

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A. W. HOWITT ON THE PHYSICAL GEOGRAPHY AND

the place I speak of, that, in shafts sunk through the detritus in the heels of those streams among the porphyritic hills, slates and lime- stones similar to those in the Limestone River are found as the bed- rock.

In the valley of the Native-Dog Creek where that stream has cut through the thin remains of Upper Devonian fossiliferous limestones and shales into the underlying porphyries, several masses of meta- morphosed sedimentary rocks of a most remarkable character are re- vealed protruding from the peaty soil and snow-grass. These have apparently been calcareous shales, but are now calcareous schists of a pale yellowish or nearly white colour, and are not only extremely altered, but are bent into the most abrupt angular contortions. I may roughly represent the appearance of these schists thus : —

Pig. 7. — Contorted Schists, Native-Dog Creek.

They present no similarity to any of the metamorphic schists of North Gippsland which I have ever seen. But I have observed that among the limestones and slates of the Limestone River there are thin calcareous bands which may represent the comparatively un- altered condition of the schists of the Native-Dog Creek. Further to the southward down the same stream, but above Fanwick, is another patch of shales and crystalline limestones, here also altered in an unusual manner, but somewhat similar to those I have just described. They appear in a deep valley from under the great por- phyritic tableland. Prom these appearances I believe that the in- dicated extension of the Limestone-River strata is not inconsistent with the probable truth.

In mentally looking over the whole district, I perceive that here and there mountains or ridges of quartz-porphyries stand out from the " Snowy-River Porphyries " or in their neighbourhood, in the latter cases being often in the Marine Tertiary areas, from which they rise as isolated hills. Taking the Wombargo Mountain as an example, I notice that grouped round the central mass of quartz- porphyries there are immense thicknesses of successive accumulations of ash, agglomerates, and felstones, which, where the deeply cut ravines show the vertical structure, are often clearly seen to be not- only bedded, but also seamed with dykes of compact pale-coloured felstone. These appearances are seen in descending from Wombargo