taining numerous impressions o£ minute bracliipoda and corals 

 of alleged Middle Devonian age.* 



These limestones and shales dip about N. 85^ W. at 65°, 

 and rest unconformably on the Silurian sediments to the north, 

 and on the brownish fragmental quartz porx^hyries which 

 make up the mass o£ the Cobberas Mountain to the south. 

 Higher up on the north-west side of the Cobberas Mountain 

 are isolated patches of reddish conglomerates, apparently- 

 younger than the shales of Coowambat. 



On the eastern side 8f the Cobberas Mountain are seen 

 dense, almost granitic, salmon-coloured porphyries, made up 

 of translucent whitish quartz crystals and prisms of orthoclase- 

 felspar imbedded in a reddish felsitic base, with plates of 

 hexagonal mica of a greenish-bronze colour, and, according to 

 the microscopic examination by my friend Mr. Howitt, F.G-.S., 

 " an amorphous, yellowish-green, apparently hydrated, mineral 

 found sparingly in small cavities." The summit of Mount 

 Cobberas consists of bosses of compact fragmental porphyries, 

 having similar petrographical characters to those on the 

 eastern side, with the addition of the imbedded fragments of 

 indurated slate and other rocks, thus forming a trappean 

 breccia. These fragmental porphyries are continuous on the 

 south and south-west side of the mountain to the sources of 

 the Native Dog Creek, where outcrops of fossiliferous lime- 

 stone are observable. This limestone is similar to that at 

 Coowambat, and probably of the same age ; but, unlike the 

 latter, it is wholly surrounded by the quartz porphyries, 

 filling a pocket in these igneous rocks. From this place 

 northerly across the Main Dividing Eange towards Limestone 

 Creek the porphyries are more silicious in character, stand 

 out in large weathered blocks, and yield a griity, although not 

 unfertile, soil. 



At Stony Creek, erosion has laid bare thick beds of fossili- 

 ferous limestone, marble and slaty shale, the first containing 

 among other molluscs the well-known Sinrigerina reticularis, 

 common to Upper Silurian and Lower Devonian formations, 

 and undescribed species of BeyricJiia and Atrypa. The marble 

 beds are crowded with stems of Actinocrinus and obscure im- 

 pressions of trilobites.f 



The unaltered fossiliferous limestones, at this place, are in 

 direct contact with the overlying porj^hyries, while the 

 crystallization of the rocks increases with the depth. This 

 would appear to confirm the suggestions made by Mr. Howitt 



* "Devonian Kocks of North Gippsland," by A. M. Howitt, F.G.S. 

 t " On Caves Perforating Marble Deposits, Limestone Creek," by J. 

 Stirling, F.L.S. Trans. Eoy. Socy. Vict., 1883, p. 11. 



