340 WOOD'S POINT DYKE, VICTORIA. [May 1902. 
19. The Woon’s Point Dyxz, Vicror1a (AustRAtiA). By FrepeEric 
Puitie Mennett, Esq., F.G.8. (Read April 16th, 1902.) 
| Abstract. } 
Tuis dyke is intrusive into a belt of Silurian (Upper Silurian) 
strata which strike in a direction somewhat west of north, and 
extend beyond Walhalla on the south. Wood’s Point is about 
75 miles east of Melbourne. It may be taken as typical of the 
intrusions associated with the Silurian rocks of the Victorian gold- 
fields. Brown, original, hornblende is the dominant constituent, but 
it is rarely idiomorphic; augite, three varieties of felspar, micro- 
pegmatite, and ilmenite are also present, in a microcrystalline or 
cryptocrystalline groundmass, ‘The rock is called a hornblende- 
porphyrite. In certain varieties cordierite occurs, and is accounted 
for by derivation from the adjacent shales. The reefs in the Silurian 
and Ordovician rocks usually occur at or near the contact with 
intrusive rocks. At Wood’s Point the reefs are nearly horizontal, 
traversing dykes and shales, the junction usually marking the 
occurrence of rich ore. The Author notes the ‘ almost invariable 
association of gold in this class of deposit with rocks containing 
original hornblende,’ 
