Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/50

24 24 A. W. HO WITT ON THE PHYSICAL GTCOGBAPHY AND

taking a general view of North Gippsland it is seen that there are isolated patches of limestones which present perfectly similar charac- ters as to position and lithological character, and, what is of more importance, an identity of fossil remains. Mr. R. Brongh Smyth's geological sketch map of Victoria well shows this. These limestone patches are usually found, as at Buchan, in the hollows of hasins formed in and surrounded hy the Snowy-River porphyries ; at the " Basin " and on the Snowy River at the junction of the Bodgers River, not far from Buchan, similarly situated ; or, as at Bindi, where the hasin is formed hy granites, quartz-porphyries, indurated Silurian and crystalline schists, in fact the "Lower Balaeozoic rock-foundation." At New Gellingall, on the Buchan River, the hasin resembles that of Buchan. At Gelantipy, however, we find three small outliers of the Buchan Limestone on the summit of the tableland, resting on the Snowy-River porphyries, and covered by late Tertiary (Pliocene ?) doleritic rocks.

These limestones are generally somewhat thick-bedded and com- pact, usually of a dark blue or blackish colour, and undulate at a somewhat low angle, but are in places seen to have been much folded at high angles. They produce a country of rolling hills or steep grassy ridges, with an excellent red soil, and lightly timbered with Eucalyptus and Acacias. " Sinkholes " are of common occur- rence, as in other limestone districts, and the scenery is strikingly soft and pleasing in contrast to the harsh and rugged mountains which frame these basins.

The age of these Buchan Limestones has been determined by Professor M'Coy as being Middle Devonian*.

At Buchan argentiferous galena and copper-ore, principally py- rites, has been found and worked.

At Tabberabbera, at the junction of the Mitchell and Wentworth Rivers, I have found a group of strata which present features dif- fering in many respects from those just described, but which, from the fossils gathered from them by me, have been referred by Pro- fessor M'Coy to the same age as the Buchan Limestones f.

The group of strata at Tabberabbera consists mainly of more or less indurated or slaty shales, which alternate with quartzites, coarse sandstones with pebble bands, and has a subordinate belt of compact dark blue limestone. The fossils are found abundantly in a black shale adjoining this ; but the limestones have not as yet yielded any thing.

The inclination of these strata is nearly as great as, and their general direction of strike and of dip approximate to, that usually found in the great series of slates and sandstones with auriferous quartz veins which are regarded as Silurian, and together with which the Tab- berabbera shales have been also folded. The extension either on the strike or laterally, I have as yet been quite unable to deter- mine ; but I believe it to be great. I have identified this group down the course of the Mitchell River nearly to Cobbannah Creek ; to the

t Report of Progress, Geological Survey of Victoria, No. 2, p. 72.
 * Intercolonial-Exhibition Essays, 1866, No. 7, p. 327.