Geology of Warrandyte Goldjidd. 535 



'■ fracture zone '' is justified, but the cause of that fracture zone, 

 and its relations to the rocks of the surrounding country, have 

 not hitherto been determined. The distribution of the quartz 

 reefs, and their connection with tlie geological structure will he 

 subsequently discussed. 



(b) Tlie Quartz Reefs. 



These have Ijeen individually described in 189G by Mr. Murray 

 (7), and in 1898 by Mr. Walter Forbes (8). The latter gives 

 full partic\ilars of the reefs then known, as to strike, dip and 

 thickness of beds, etc. It is therefore unnecessary to deal 

 minutely with the reefs, even if that were possible, which it is 

 not, as at the time of my visit to Warrandyte most of the later 

 mines were closed down, and the old workings are as a rule in- 

 accessible to any depth. The purpose kept in view during the 

 examination of the country, was not to record minute informa- 

 tion as to particular reefs, but to endeavour to grasp the rela- 

 tion of the reefs to geological structure, and by this means to 

 throw some light on the cause of their distribution. A general 

 account will therefore be sufficient, unless there be any point? 

 of special interest. 



The reefs are associated with the minor folds, and generally 

 with the anticlines, although the Caledonian and Bendigo lines 

 are in the Caledonian Syncline. Tliey are approximately 

 parallel in strike to the direction of the axial lines, but at times 

 cut across the strata at slight angles. Their strike varies from 

 about N. 10 deg. E. to N. 25 deg. E. Their underlie is some- 

 times to the east and sometimes to the west, generally close 

 to the vertical. They ai-e usually thin, ranging from about 3 

 inches to 2 feet, the majority probably being under a foot in 

 thickness. Most of the workings are shallow, not exceeding 

 200 feet in depth, and being very little below the ground- 

 water level. The dee]>est mines are the " Victory " (whose 

 greatest depth was about 275 feet) and the " Caledonia " (600 

 feet). The quartz is in places fairly well mineralised. 



The lengths of the reefs, so far as ascertainable, appear to 

 correspond in length with the folds of the rocks, or those por- 

 tions of the folds that have been subjected to great pressure. 



