346 Morris Morris: 



more fragmentary, and intenst-ly pleocliroic. There is also a 

 micaceous dust shinunering tlnough a ground mass composed of a 

 granular maze of quartz, felspar, and biotite. and a glassy residue. 

 The flexure of the biotite and the coi'responding arrangement of 

 the other fragments indicate marked How structure. Ilmenite is 

 still abundant. 



e. — The U 2) per or H ypersthene, or formal Dacite Series. 



This is the last and probably the gi'eatast series of the system. 

 Though occupying only the upper portion or crest of the Dande- 

 nongs in the north, it extends over 10 miles south, passing beyond 

 the Gembrook railway line as far as the granodiorite, and at the 

 same time spreading west as far as Lower Ferntree Gully, and east 

 to Monbulk and Emerald. 



This normal Dacite is distinguished from the preceding series 

 thus : — Its porphyritic character is much less apparent, the pheno- 

 crysts being small, Avhile quartz phenocrysts are very seldom seen ; 

 hypersthene is very abundant, though it appears to be quite absent 

 from the preceding series, except possibly the first. Even in the 

 series immediately underlying the normal Dacite, I have not found 

 one occurrence of hypersthene. Orthoclase is present, but in a 

 much lower ratio to plagioclase. 



This dacite shows no difference from the r]>wt'V dacite 

 described by H. ('. Richards (16), except that here lutile sometimes 

 occurs in well-formed ciystals. 



Schistose Dacite.- — In certain places, secondary biotite has formed 

 in clusters, surrounding the hypersthene to some extent, and the 

 ilmenite to a greater extent. At Mt. Dandenong this alteration is 

 not easily noticeable, but going east towards the Evelyn fault valley, 

 it becomes more marked, and on the highest ))art of the hornfels 

 ridge, that forms the eastern wall of tliis valley, tliere are a few 

 small i-esidual ])atches of schistose dacite. Of tliese patches, one at 

 least is almost, if not (|uite, isolated by the Silui'ian hornfels from 

 the main mass of the dacite of the Dandenongs on tlie west of the 

 valley. Other i)atclies run down the eastern sloi>e of the valley into 

 the alluvium. It is clear, therefore, that the normal dacite rests on 

 the Silurian as a lava How. (See Plate XXX., Fig. 4.) 



Orii/iit of the Schistose Dticite. — Tliese i)atches of dacite are not 

 all equally altered. In some of tliem the schistose structure is 

 emphatic; in others, it is si'arcely peice])tible in hand specimens. 

 The following reasons present, themselves for attributing their con- 

 dition to plutonic and hypabyssal intrusions of granodiorite : — 



