Metamorphic and Plutonio Rocks at Omeo. 127 



the contact ; the second group includes the more strongly 

 metamorphosed mica schists, with tourmaline crystals and 

 the s:neissose schists at Wilson's Creek. The alterations in 

 the second of the above groups I attribute to metamorphism 

 produced by the intrusive granites, and by the younger 

 porphyritic rock-masses connected with them. Thus in one 

 sense the metamorphic rocks adjoining the contact might be 

 not inappropriately spoken of as " contact schists," if it is 

 desirable to Kmit the use of the term ''regionally meta- 

 morphic," to those schists whose peculiar mineral and 

 physical composition, and structure, are the result of 

 dynamical metamorphism. 



The intrusive rocks in the area herein dealt with are 

 granites, whose western extent I have not determined. 

 This mass of granite has associated with it marginal masses 

 and strong dykes of muscovite granite, passing in places 

 into aplite. These are clearly younger than the main 

 granite mass, as are also other dykes of pegmatite, aplite, 

 and graphic granite, which are found at the contact or 

 beyond it in the schist area. The granites, therefore, taken 

 as a whole, including all the above varieties, represent an 

 intrusion of plutonic rocks of several consecutive ages of 

 the same period of plutonic invasion, and the series is 

 increasingly acid, the later dykes being mainly of orthoclase 

 (microperthite) and muscovite, or of orthoclase and quartz. 

 Finally, the veins and even strong dykes of crystalline 

 quartz, or of quartz and tourmaline (schorl) which are 

 associated with these gTanites, represent the last portions of 

 still fluid (uncrystallised) magma. 



The line of contact is an irregular one, although the 

 general direction is constant, and approaches the mean 

 strike of the lower palseozoic formations. The invasive 

 rocks protrude into the schist tract in promontories, and 

 appear within it in isolated patches laid bare by denudation, 

 but which no doubt, are connected below with the main 

 granite mass. Thus when we picture to ourselves this mass 

 adjoining the schist contact, and the numerous surface out- 

 crops and veins of granite in the schists, we must see that 

 these all represent a much larger extent of granite sub- 

 terraneously, which at one time as a magma, invaded the 

 schists both horizontally from the contact and vertically 

 from below, where it " corroded " its way upwards into the 

 schist ]nasses. An inspection of the contacts laid bare by 

 denudation, shows that the intrusive masses now occupy 



