538 /. T. Jubtson: 



independent fissures, each one (when followed to the north) 

 more to the west than the preceding one. In these quartz has 

 been deposited. The faults have moved the reef, and are tliere- 

 fore clearly subsequent to it, and consequently to the formation 

 of the splices. These are the main structural points of inte- 

 rest in the mine. 



(c) Dykes. 



The two dykes east of Warrandyte have already been de- 

 scribed. There are small irregular auriferous quartz veins in 

 the rock, which at the surface is now decomposed to a clay. 

 These quartz veins have evidently tilled the cracks formed in 

 the dyke rock on cooling, and are therefore subsequent to the 

 intrusion of the dykes. The latter have been worked to 

 shallow depths, and the results are given in the mining history 

 of the field. 



(d) TJtt Cause of tJie Horizontal Limitation of the Field. 



The Warrandyte goldfield occupies very little area. Few reefs 

 cross the Yarra, and the latter may be regarded, roughly speak- 

 ing, as the northern boundary of the field. On the west and 

 south, Anderson's Creek (with some few exceptions a little to 

 the south) is the boundary, whilst on the east, Parson's Gully 

 and a line drawn to the east of the Caledonia Mine, form the 

 remaining boundary. This peculiar limitation therefore calls 

 for explanation. 



The question involves the consideration of the relation of the 

 reefs to the folds of the rocks, and the more westerly of the 

 two dykes to the east of Warrandyte. As has been seen, the 

 reefs appear to be connected with the folds, and to bear a 

 distinct relation in regard to their horizontal lengths to the 

 lengths of the folds. The dyke on the other hand has a direc- 

 tion and a position that suggest an influence on the lengths of 

 the reefs. The view held by the local miners is that the dyke 

 has in some way cut the reefs off. This could happen in two 

 ways — viz., faulting and intrusion of the dyke subsequent to 

 the fornuition of the reefs ; and the formation of the dyke prior 

 to the reefs, the former acting as a barrier to the latter. 



