Granitic and Palaeozoic Mocks, Dandenong. 113 



The age of the granite at Walhalla has an important bearing 

 on the geology of the goldfield of that district, but no fully 

 satisfactory evidence of its age has hitherto been got near there. 

 The granite is marked on the Geological Sketch Map of Victoria 

 as extending almost continuously from Dandenong to Mount 

 Baw Baw and Walhalla, and therefore its age at these three 

 places is probably the same. 



As the two groups of granites are not distinguished in the 

 geological maps of Victoria, at the suggestion of Professor 

 Gregory, I have examined the granite near Dandenong to try 

 to determine its age relative to the lower palaeozoic beds.^ 



II. — Topography. 



Dandenong is eighteen miles south-east of Melbourne, on the 

 creek of the same name, which flows from the swampy land to 

 the north-east of the Dandenong ranges. The township is about 

 69 feet above sea level, on slightly undulating country, to the 

 north-east of which rise the " Dandenong Ranges "; but as these 

 hills are isolated or connected by very low saddles, a better name 

 would be the Dandenong Hills. Near Dandenong there are three 

 types of rocks : — 



1. Granite, forming the picturesque foot hills of the pro- 



posed National Park, in the old Police Paddocks, and 

 the hills to the east and north-east. 



2. Dacites, similar to those of Mount Dandenong, occurring 



near Ferntree Gully. 



3. Lower palaeozoic rocks, on the flanks of the granite, 



and forming the low, undulating country towards 

 Oakleigh. 



III. — Literature. 



There is not much literature on the geology of Dandenong 

 district. 



The earliest is a report by the late A. R. C. Selwyn on a 

 geological map of the country between Port Phillip Bay and 



1 In the absence of fossil evidence there is no certainty whether the rocks be ordovician 

 or Silurian, but the discovery, by Mr. Ferguson, of ordovician fossils in the Mornington 

 peninsula suggests the possibility that the lower palaeozoic rocks in contact with the 

 granites at Dandenong are also ordovician. In that case the Dandenong-Baw Baw massif 

 may be pre-silurian though post-ordoviciaii. 



