Plenty River and Andersons Creek. 169 



The Warrandyte goldtield is mainly confined to the area of 

 country bounded by the Yarra River, Anderson's Creek and 

 Parson's Gully. (Reefs extend beyond these boundaries, but are 

 not too plentiful.) The cause of this T hope to explain in a 

 later paper. For the present, it will suffice to note the fact. 

 The rocks of this area are of silurian age, and consist in part 

 of coarse sandstones, grits and conglomerates. Quartz in the 

 form of reefs and veins, filling joints and others fissures, is 

 widespread and abundant. By its injection the rocks have be- 

 come hardened and more resistant to denudation. The conglo- 

 merates, grits and coarse sandstones, and, apparently, also the 

 quartz reefs, gradually die out south of the Anderson's Creek 

 Goroe ; but the latter is not the actual boundary of the reefs or 

 of the hard rocks. This is well shown by the Great Southern 

 Hill, which forms the continuation of the ridge known as Fourth 

 Hill on the northern side of the gorge. This ridge forms the 

 crest of an anticline, and the effect of the hard rocks of the 

 Great Southern Hill is well illustrated in the small gully known 

 as Beauty's Gully, which runs eastward from its mouth in an 

 almost level line till it meets the ridge, when it sharply rises. 

 To the south of Beauty's Gully other easterly tril^utary gullies 

 of Harris's Gully extend much farther to the east, on account, 

 no doubt, of the rocks there being softer. 



To the east and west of Parson's and Harris's Gullies 

 respectively, the conglomerates, grits and thick sandstones 

 together with the quartz reefs, practically disappear. 

 The rocks consist mainly of shales, and are therefore 

 softer and liable to more rapid denudation than the 

 coarser-grained silicified rocks of the Warrandyte goldfield area. 

 Here again the effect of the hard rocks may be seen in Parson's 

 Gully. On its western side the tributary gullies are short and 

 steep, whilst on the eastern side they are long and well graded. 

 The strike of the silurian rocks of the district is a few degrees 

 to the east of north. The directions of Parson's Gully, Harris's 

 Gully, and the upper and lower Anderson's Creek approximate 

 towards the strike of the rocks, while Anderson's Creek Gorge 

 cuts across both the strike and some of the hardest rocks. 

 Parson's Gully and the upper part of Anderson's Creek on the 

 eastern side, and Harris's Gully and the lower part of Ander- 



