382 PROCEEDINGS OP SECTION E. 



DEVONIAN. 



There is a well marked stratigraphical break between the 

 underlying Silurian beds and the lowest members of the Devonian 

 series. The sedimentary rocks of the latter occupy basins in the 

 former, and are found in isolated areas. 



The lowest Devonian rocks are certain quartz porphyries, 

 fragmental porphyries, and felsitic rocks — the products of volcanic 

 activities which marked the close,of the Silurian Period. These 

 rocks occupy a large part of the western watershed of the Snowy 

 River. At several points, notably the Cobberas Mountains, 

 Wombargo Mountains, &c., are very distinct remnants of this 

 period of igneous action — round these centres are grouped beds of 

 consolidated ash and tufa, while resting in hollows in these igneous 

 masses are beds of conglomerate, shale, and crystalline limestone 

 containing fossils of distinctively Middle Devonian age. Such 

 Middle Devonian areas now form mere pockets in the general land 

 surface, and have suflered extensive denudation. The principal 

 Middle Devonian areas are Bindi in the Tambo Valley ; Buchan 

 in the Snowy River watershed ; Cowambat and Native Dog on the 

 flanks of Mount Cobberas, at the head of Cowambat Creek and 

 Native Dog Creek respectively, and at Tabberrabei^a and Cob- 

 bannah Creek, in the Mitchell River valley. 



The lithological and pal?eontological characteristics of the Middle 

 Devonian areas are as follows : — 



At Bindi, on the east side of the Tambo, beds of blue crystal- 

 line limestone rest on subordinate beds of conglomerate. The 

 limestone beds are inclined at an angle of from forty to sixty to the 

 west, and contain the following fossils — Phragmoceras subtrigommi, 

 Spirifera loevicosta, Chonetes australis, Favosites Goldfusi, ^pirigera 

 reticularis, Stromatopora concentrica, Cystipliyllum, Pterinea, with 

 fragments of Asterolepis* 



On the west are beds of shale, felspathic sandstone, and in the 

 Main Dividing Range masses of conglomerate, and red sandstone, 

 as at Mount Tambo. The Mount Tambo beds have been classed 

 as Upper Devonian by Mr. Howitt, although I am not yet satisfied 

 that they are really superior to the Bindi Limestones, and may 

 after all form part of the Middle Devonian series. 

 I The Buchan beds are situated between the Buchan and Merrindal 

 Rivers, and occupy a hollow in the porphyries. In lithological 

 character they are similar to those of Bindi, but darkerin colour, in 

 fact nearly black, and are very much contorted. These beds are 

 between four hundred and five hundred feet thick, and only form 

 part of the group. The lower members consist of coarsely 

 aggregated felsitic breccias — the coarseness of the materials de- 

 creasing, but with alternations of texture, in ascending, and in 



* Stirling, Notes on the Bindi Limestones. Progress Report, Geol. Survey Victoria, No. 3, 

 p. 188. 



