392 PROCEEDIKGS OF SECTION C. 



contains numerous spherulites of chalcedony, each giving- a perfect 

 interference cross between crossed nicols. The felspar is orthoelase, 

 and varies in color from Avhite to pink. Twinning on the Carlsbad 

 type is frequent. In texture the rock differs a good deal, in some 

 places being very fine grained and in others quite coarse. I once 

 picked up a specimen prismatic in shape, but have not found this 

 variety in situ. Both the quartz and felspar often show well- 

 defined crystal boundaries ; in very thin sections there is 

 practically no portion AA'hich cannot be resolved 



Among other rocks from the Grampians, Mr. Murray, in his 

 Handbook, speaks of a syenitic porphyry as catalogued by Mr. 

 A. R. Selwyn, in 1868. Whether the particular rock I am 

 describing is (he one meant I cannot say, but the name agrees 

 Avith its mineralogical composition. 



Von Cotta, in his " Classification of Rocks," says : — " In dis- 

 tinguishing and naming these transition rocks their geological 

 relations must always to some extent be taken into account." As 

 will presently be shown, a typical quartz-porphyry is very abun- 

 dant on the west and also to the south of the Victoria Range, and 

 it is difficult to resist the conclusion that the two groups of rocks 

 are closely connected. Though there is no actual junction visible, 

 an outcrop of Grampian sandstone separating them, there seems 

 to be a gradual passage from the more coarsely crystalline rocks of 

 Victoria Valley, through the finer grained variety, to the quartz 

 porphyries of Cavendish, and of the syncline between the ^"ictoria 

 and Dundas Ranges. I wish it to be understood that my remarks 

 on the granite of Victoria Valley apply only to the more southerly 

 outcrop, as I have not examined the northerly one. 



On either side of the former the Grampian sandstones dip to the 

 west at from 15° to 20°, but break off abruptly on the eastern 

 escarpment of both the Victoria and Serra Ranges. The Victoria 

 Valley is thus not a syncline, and the short distance between the 

 ranges — about eight miles near Mount Victoria, the most southerly 

 point of the Victoria Range, and less than this a few miles to the 

 north — forbids the assumption that there was ever an anticline 

 with its accompanying synclines between these two similarly 

 dipping ranges. If they were formerly connected the original 

 anticline would not be on the site of this valley, but some distance 

 to the east of the Serra Ranges. It consequently follows that the 

 elevation of the mountain chain must then have far exceeded that 

 of the highest peak in the present Grampians. 



The central boss of granite to the west of Dundas Range is 

 surrounded either by later trappean and volcanic rocks or by those 

 ancient crystalline schists which probably form the bedrock over 

 the whole region. Speaking of the last, Mr. Selwyn remarks : — 

 " Little is yet known of the relation of these beds, and whether 

 they represent a series older than Silurian or are some highly 

 metamorphosed lower beds of the Grampian sandstone group is 



