GNEISSIC OE METAMORPHIC SERIES. 9 



as yet quite unknown among the southern gneissics. These miner- 

 als occur together in some of the beds, in others they are found 

 separately. 



Much as the sub-division of this vast series of rocks would be 



desirable, if it could be carried out safely, the 

 Stratigraphical sub- 

 division of gneissic series results ot the survey would not in this case justify 



prac ica -^ ^ p regen ^ ag ^ g. enera i stratigraphical rela- 



tions of the principal groups of strata were not ascertained with suffi- 

 cient certainty, owing partly to the disturbed and broken character of 

 the strata, partly to the great extent and thickness of superficial depo- 

 sits, and partly also the limited time which could be devoted to the work. 

 In the absence of organic remains the sub-division of a great series of 

 rocks must be based on well determined relations whether of infra or 

 supra position of the several members of such series,, and where such 

 relations cannot be ascertained, as in the case in question, no sub-division 

 should be attempted. A much closer survey than that now carried out, 

 and laid down on better maps of much larger scale, would very likely 

 supply many of the data now wanting to correlate the different rock 

 groups (to use this term in a merely geographical sense) . 



At present as the relative positions of the principal groups remain 

 to a great extent undetermined, it makes but little difference in what 

 order they are. considered, but for convenience in describing it may 

 be as well to take them in a geographical order from south-west to 

 north-east. 



Although the gneissic rocks are not safely divisible into groups 



based on well-determined stratigraphical positions, 

 Petrological sub-divi- _ . ■ ■ • . 



sion into schistose and they can easily be classed in two divisions 

 granitoid areas or bands. -, -, , . ,■,.-,-,.„„ 



marked by great petrological differences. These 

 two groups are the Schistose and the Granitoid. They occur distributed 

 in several bands, of which four are principal ones and equally divided be- 

 tween the two groups. The bands which are shown in the annexed sketch 

 map,/?. 1, follow, on the whole, a north-east-by-north to south-west-by- 

 south direction ; but the axes of the granitoid bands are by no means 



( 9 ) 



