Notes on a Geological Sketch - Section 

 through the australian alps. 



By James STiKLi:jfa, F.L.S., Corr. Member. 



Plates I. and II. 



[Eead February 5, 1884.] 



An examination of the different rock masses wliicli compose 

 the Australian Alps reveals many interesting geological 

 features, not only in respect to their stratigraphical relations, 

 but in the evidences of long-continued denudation which has 

 laid bare the deep-seated crystalline schists and their intrusive 

 rock masses. The surface configuration over which the sec- 

 tional line has been determined is most varied, passing from 

 the porphyritic bosses of the rugged Cobberas Mountains, 

 across the Upper Silurian slates and marble-beds in the 

 valley of Limestone Creek, through the metamorphic schist&i 

 and granites of the Mitta-Mitta source-basin and its included 

 Omeo plains and tableland, to the Main Dividing Eange ; 

 thence across the deep gorge formed by the Dargo Eiver 

 (where the metamorphic schists merge into unaltered Lower 

 Silurian slates and sandstones) to the basaltic tableland of the 

 Dargo high plains, which has sealed up the river valleys of 

 Miocene age. 



The lithological characters of the different rock masses are 

 as follows: — At A are a series of open mossy upland flats, 

 forming a low gap in the Main Dividing Eange. These flats 

 are made up of deposits of Tertiary or Post-Tertiary gravels, 

 containing stream-tin and fine gold, and rest on a bottom of 

 decomposing granite. The gravels are overlain by a moderate 

 depth of alluvium, held together by the thin wiry interlaced 

 roots of various Alpine shrubs. Samples of stannite in a 

 quartz matrix have been found in the ridges in situ, indi- 

 cating a probable lode not far distant. On the spurs from 

 Mount Pilot the granite merges upward into a coarse granitoid 

 schist, while on a high lateral range proceeding westerly the 

 latter rock passes into a series of highly-inclined argillaceo- 

 mica schists.* 



Descending the southern slopes of Mount Pilot, towards 

 Porest Hill, the open park-like basin of Coowambat Flat is 

 reached ; here are seen outcrops of yellowish to bluish and 

 greyish shales, calcareous shales, and limestones, the last con- 



