308 REPORTS OF RESEARCH COMMITTEES. 



Blue Mountain (Wuid Kruirk), on the Main Divide, 4 miles 

 north of Blackwood township, consists of a volcanic rock which 

 somewhat resembles some of the basic trachytes of the Macedon 

 district. It may be described as an anorthoclase-oliviue-trachyte. 



Thefee rocks from Western and Cetntral Victoria ?<rei most 

 probably of mid to late Cainozcic age, and are to' be described 

 later in a publication of the Geological Survey of Victoria. 



An olivine-anortlicclase trachyte occurs at the north end of Stony 

 Creek Gorge, 1^ miles south from Daylesford. 



From North-eastern Victoria, a few years ago, the Country 

 Roads Board submitted tc^ the writer for examination a boulder 

 found among the coarse gravels of the Ovens Valley, near Bright. 

 On microscopic examination it proved to be an alkali rock of a 

 type hitherto ixndescribed in Victoria. It contains nepheline and 

 aegirinei in a fine^ grained ground mass and is probably a dyke 

 fock, and so is best described as a tinguaite. 



. Recently the writer has described a series of dyke rocks, collected 

 by Mr. Kenny, of the Geological Survey of Victoria, during the 

 inapjjing of an area between Hairietville and the Main Divide, 

 in the watershed cf thei Upper Ovens River. They occur as igneous 

 intrusions intO' slate and sandstone beids, probably of Lower 

 Ordovician age. Brief reference will suffice here as the descrip- 

 tions are to be published as an appendix to Mr. Kenny's report 

 in a Geological Survey publication. No less than eight of these 

 rocks are of a highly alkalic character. Five cf these rocks 

 occur as small volcanic pipes ranging up to about 20 acres in area ; 

 while the remainder are dykes from a few feet up' to 75 feet in 

 width. 



All these eight rocks contain nepheline, alkali-felspar and 

 soda augite, and the rocks consist of tinguaites and nepheline 

 phonolites. 



It is now probable that the boulder of tinguaite from the 

 Ovens Valley, near Bright, mentioned above, was derived from 

 this remarkably interesting area of alkali-rich igneous rocks. 

 Their age, apart from being post Lower Ordovician, cannot be 

 definiteiy placed, but is quite probably not older than Mid- 

 .Cainosoic, since some of the rock types are little, if at all, altg^red. 



It will be noticed, in conclusion that, up till 1911, when the 

 writer first described the ej^istence oi nepheline in dykes at Omeo, 

 no felspathoid bearing rocks had been definitely recognised in 

 Victoria. Since that date, 25 felspathoid bearing rocks have been 

 recognised or described apart from other alkali rocks of a lessi 

 alkaline character. With these additions to' our census of alkali 

 rocks, Victoria must now rank as a definitely alkali-rich province, 

 and there can be no doubt that closer examination of our Cainozoic 

 volcanic rocks Mill in the future ccnsiderablv extend this list. 



