BIOLOGY OF SNOWY RIVER AREA 1S1 



bargo and iNlt. Statham, and extending south towards Buchan, 

 while to the easl il drops \cvy steeply to the valley of the Snowy 

 River. 



The porphyries arc very hard, and their resistance to erosion 

 lias resulted in the development of steep rocky gorges along many 

 of the swiftly flowing fivers in the area. 



At Suggan Buggan, and along the Snowy River at the junction 

 of the Deddick River and a1 Campbell's Nol>, older granitic rocks 

 are exposed. I n these areas, the river valleys open out, becoming 

 relatively broad and flat, and the topography is much less rugged. 



The older sedimentary rocks (Ordivician) which underlie the 

 Snowy River Porphyries were not examined during this prelimi 

 nary survey. 



Notes on Hocks Collected 

 Granitic Rocks. 



The rocks exposed at Suggan Buggan, at, the junction of the 

 Deddick River and at Campbell's Nob are v;vc\\ even textured, 

 plutonic rocks containing quartz, white felspar, and abundant 

 biotite, with a little hornblende in places. Sections have not yet 

 been cut, but in hand specimens, the rock resembles granodiorite. 

 Microscopic examination of a crushed specimen revealed abun- 

 dant plagioclase felspar, bul the ratio of plagioclase to orthoclase 

 cannot be determined without sectioning. Xenoliths of sedimen- 

 tary rocks in all statics of assimilation are common at Suggan 



Buggan and at the Snowy River Bridge. 



These grey granitic rocks are older than the overlying Snowy 

 River Porphyries. Evidence for this can be seen in road cut- 

 tings above the Suggan Buggan River, where sections have 



exposed at least, one large mass and a few small rounded boulders 

 of 1 he granil ic rock embedded in 1 he porphyries. < )n t he western 

 bank of the Snowy River, just north of Campbell's Nob, similar 

 boulders can be seen embedded in fine-grained porphyry- (Plate 

 13, lower. 



Snowy River Porphyries 



This series includes many types of rock, most, of which appear 

 to be of volcanic origin. They have been described in detail by 

 Howitt (2), and only specimens collected on this survey are 

 described here. 



(a) Quartz Porphyry.— Massive quartz porphyry occurs 

 south of Currie < heok, approximately two miles west of t he < Jelan 

 tipy-Wulgulmerang Road. This rock is very uniform, and con- 



