Geology of Broadine<uloivs. 175 



Alluvium. 



TTie alluvium occurs in small quantity along the bed of the 

 creeks. It is obviously derived partly from the granitic area, 

 partly from the basalt, and partly from the silurian sediments. 

 It is omitted from the accompanying map for the sake of 

 clearness. 



In conclusion, I should like to gratefully acknowledge the 

 help of Professor E. W. Skeats and Mr. H. S. Summers, M.Sc, 

 throughout the year 1910, when the work detailed in this paper 

 was carried out. I am also indebted to Dr. Pritchard for 

 information concerning shells from the limestone, to Mr. H. C. 

 Richards, M.Sc, for the analysis of the granite, and to Mr. H. 

 J. Grayson for the micro photographs. Mr. Grayson also gave 

 valuable and greatly appreciated assistance in the preparation 

 and stainino' of the rock slides. 



Summary. 



The Broadmeadows area includes a low granitic hill called 

 Gellibrand's Hill, which gradually rises from a river valley to 

 the south. Tlie hill and valley are surrounded by a level basalt 

 plain. 



In the valley and central portion of the area a folded series 

 of Silurian sandstones, mudstones and shales outcrop. The 

 granite is intrusive into this series. A chemical analysis by 

 Mr H. C. Richards, M.Sc, and a petrographical examination 

 prove that the granite is to be correlated with the devonian 

 granodiorites of Victoria. In part the granite is kaolinised. 



North-west of the Broadmeadows township occurs a volcanic 

 series which rests, with only a thin intervening iron-stained clay 

 bed, on both granite and silurian rocks. This series has been 

 found chemically and petrographically related to the older 

 basalt series of Victoria. 



A tertiary quartzite and grit series is found underlying the 

 newer basalt plain and outcrops along the valley walls. It is 

 probably younger than the older basalt, but the relations are 

 not clear. 



