378 PROCEEDINGS OF SECTION E. 



argillaceous members of the series into dense granitoid masses is 

 traceable — as on the Mayford spur — from the Dargo River over 

 the main divide towards the Cobungra River. 



The less altered beds, vary from argillaceous to arenaceous 

 in composition, with slaty cleavage. The preponderating dip 

 is to the east (although the dip varies from 70° to the vertical), 

 from which we may infer that the whole of the beds were tilted 

 over to the west. The strike varies between north-north-east 

 and N. 60° W., although in some localities where certain plu- 

 tonic masses have invaded the sediments, the latter have been 

 thrust out of the normal line of strike. On the whole the strike 

 is at an angle with the axial line of the main divide. 



On the surface the argillaceous rock masses are yellowish and 

 brownish, but in all the mines they are of a bluish or greenish- 

 cast of colour, and of a slaty structure. The arenaceous beds 

 are varied in structure from soft and friable sandstones to coarse 

 quartzose grits. I am not aware that any conglomerate beds 

 which might be considered as representing the base of the series 

 have yet been discovered. 



There is a noticeable absence of fossils from which the actual 

 age of the beds might be determined. They present lithogra- 

 graphical resemblances to the normal Lower Silurian sediments 

 elsewhere. On the eastern watershed of the Snowy River, as at 

 Deddick and Goongerah, are certain black slates, apparently part 

 of the series which contain undoubted Lower Silurian organic 

 remains, such as Diplograptits recta7i(/n.Iaris, M'Coy ; Didymo- 

 graftus cadiiceim^ and Diplogra'ptus foliaceus.''' The author has 

 recently found similar Graptolites on the Yalma River in similar 

 black slates, t 



Whatever may have been the character of the rocks upon which 

 these Silurian sediments were laid down, there are abundant 

 evidences that a granitiform mass underlies the whole of the 

 sedimentary rocks over the greater part of the area known as the 

 Australian Alps, and, as has been remarked, " were the whole of 

 the granite stripped of the superior strata, without being itself 

 denuded, it would present an extremely uneven and irregular 

 surface, for we find on examining tlie streams, that in places the 

 Silurian strata descend below the general surface of the granite 

 and are much contorted and fold back on themselves, while in 

 other places we find bosses of granite appearing through the 

 Silurian ridges of slate." On the whole those sediments classed as 

 Lower Silurian are more indurated and slaty, and present a higher 

 angle of dip than similar sediments in which undoubted Upper 

 Silurian fossils exist. It is doubtful if the classification of a 

 considerable area in the Mitta Mitta and Ovens River valleys as 



* M'Coy, Prodomus Pal. Victoria, Decade I., p. 12, 



+ Stirling-, On Prospecting- Parties, County Croajingolong. Reports, Mining Registrars, 

 Victoria, March, 1888. 



