138 



H. S. Summers: Dacite and Granodiorite. 



After the extrusion the remaining magma would continue crystal- 

 ising, but with a lower initial temperature than was the case in the 

 Macedon area. Complete solidification would take place in a shorter 

 period (other conditions being equal), so that the sinking of crystals 

 ceased while the silica percentage of the plutonic type was below 

 that of the extended rock. 



The Mount Dandenong and Healesville areas are more complex 

 as toscanites and rhyolites are associated with the normal dacites. 

 No reliable analyses of the plutonic types in these areas have been 

 published. Mr. M. Morris has been working out the relations in these 

 areas, but has so far not published the results of his work, so that 

 they cannot be discussed at present. 



-f-4-4--h + + + 4--fy 



MIOCENE 



DEVONIAN 



DEVONIAN 



Traclivte, etc. 



t + + + 

 Granodiorite. 



OllDOVrCIAN 



UiHirili 



Uacite 



Slate, etc. 



