PHYSIOGRAPHY OF SOUTH GIPPSLAIND. 457 



Upper Silurian. 



Rocks of this age outcrop on the northern watershed of the 

 Latrobe and on the coast fiom Cape Liptrap to Shallow Inlet, 

 extending to Foster and Turton's Creek. Along the coast from 

 Cape Liptrap to Waratah Bay the rocky strand is wholly occupied 

 by these Upper Silurian sediments, intruded upon by aphanitic 

 and diabasic dykes. The beds are greatly contorted, and consist 

 of alternating dense shales, silicious sandstones, schistose grits, 

 conglomerates, and limestones — the last converted into murbles, 

 and showing splendid instances of the effects of contortion. The 

 limestones near the quarries at Waratah Bav yield an abundance 

 of corals, which are pronounced by Sir F. McCoy, F.R.S., to be 

 new, and are now being examined by him for specific naming ; 

 several univalves Hud bivalves are also present, the latter including 

 such widely distributed genera as Atrypa spirigerina., &cc. The 

 analysis of this limestone by Mr. Co<mo Newbery gave — carb. of 

 lime, 94-90 ; silica, 2-25 ; iron, 2-85 ; magnesia, traces ; water, 

 t)"5. It is therefore a good stone for lime, and for such has been 

 extensively quarried to supply the Melbourne market. 



On the western shore of Corner Inlet, at a locality known as 

 Yanakii, the Silurian rocks all rest on the granite of Wilson's 

 Promontory. I have not noted any contact metamorphism, so that 

 it is difficult to say if the former are laid down upon the latter or 

 whether the granite is intrusive. Mr. Reginald Murray, however, 

 inclines to the view that they may be so.^' The curvatiu'e of the 

 Silurian at Waratah Bay may be due to forces exerted during 

 a period of Devonian plutonic activity. 



Granite, 

 cape vvoolamai. 



Cape Woolamai, which rises from Phillip Island to a height of 

 over 3()0ft., is composed entirely of red granite. Microscopically 

 it IS a medium-grained granite composed of quartz, mica, and 

 felspar, in which the pink or red felspar predominates. \ slice 

 prepared and examined by me jjave the following petrographic 

 characters: — 



Quartz. — Mostly allotriomoiphic. Inclosures consist of small 

 flakes of biotite or of idiomorphic orthoclases and small 

 cavities. 



Felspar. — Most notable felspar is microperthite, an inter- 

 laminated aggregate of orthoclase and plagioclase with the laminae 

 parallel to the orthopinacoid of orthoclase, appearing as fine stripes, 

 on the two principal cleavage planes. Many of the orthoclase 

 crystals .show alteration to sericite. The ])lagioclase felspars are 

 idiomorphic as to the orthoclase and exhibit polj'senthetic twinning. 



* Proir. Rep. mid GpoI. Sur.. Vie'oria, p. laS, vol. 3. 



