130 Proceedings of the Royal Society of Victoria. 



IV. — Summary of Conclusions. 



The evidence of the microscopic structure of the rocks and 

 their relations in the field both point to the following con- 

 clusions: — First, there is no evidence of a gradual passage from 

 the ordovician to the schists and gneisses. The two rocks have 

 a fairly sharp junction, and their strike is not parallel. Both 

 rocks have been greatly disturbed since ordovician times, so that 

 they have been crushed together, and a clear section showing an 

 unconformable junction between them cannot be expected. 



The ordovician rocks appear to be decidedly younger than the 

 schists, for not only are they less altered, but they are clearly 

 ■clastic rocks, and they appear to have derived most of their 

 materials from pre-existing igneous rocks; they might easily have 

 been formed as a series of shore deposits, derived from the 

 weathering of the adjacent schists. 



That the ordovician rocks are a later series than the schists 

 is rendered further probable by their general distribution 

 in the district, as represented by the Geological Survey map. 

 The granitic rocks of Yackandandah have cut through both 

 series, while those at Beechworth are intrusive only into 

 the ordovician rocks. Had the metamorphic rocks been 

 produced by the alteration of the ordovicians we should 

 have expected the rocks close to the great plutonic in- 

 trusions to have been the most changed ; but on the 

 contrary the metamorphic rocks that extend from Indigo 

 Creek to Wodonga are separated from the granites of the 

 Pilot Range by a narrow band mapped as unaltered ordovician. 

 I have not verified the existence of this band, but the mapping 

 and the theory expressed in the legend of the map are clearly 

 inconsistent. A further objection to the view so long ofiicially 

 accepted is that the distribution of the metamorphic rocks of the 

 Beechworth district does not bear any relation to the granitic 

 instrusions as we might expect had the metamorphic rocks been 

 formed from the ordovicians. 



We may therefore conclude that the schist series is a pre-ordo- 

 vician series, on which the ordovician and silurian rocks have been 

 laid down unconformably. The schist series may be of Cambrian 

 age in the absence of evidence to the contrary, but considering 



