70 The Sedimentary, Met amorphic, 



This analysis may be calculated, after allowing for the 

 ferric hydrate, as being of the composition of T99o Mol. 

 free quartz, *856 Mol. magnesia-mica, and '400 Mol. alkali- 

 mica, which is nearly in the proportion of 5 : 2 : 1 ; but in 

 this calculation the small amount of triclinic felspar is 

 disregarded. 



As I have before said, it is extremely rare to find even 

 traces of sedimentary rocks on the eastern side of this part 

 of the Tambo River ; that is to say, which can be determined 

 at first sight as being such. There are nowhere those tracts 

 of alternating argillaceous and arenaceous beds tilted at high 

 angles, and otherwise showing - the familiar facies of the 

 Silurians of North Gippsland. Those schistose rocks on 

 the eastern side which can be determined as more or less 

 completely metamorphosed sediments are of limited extent, 

 are much broken and disturbed, and in places so much 

 involved with intrusive igneous rocks, and so greatly 

 crystallised, that it becomes extremely difficult to determine 

 whether certain samples are to be looked upon as the com- 

 pletely metamorphosed sediments, or as some of the schistose 

 varieties of the intrusive masses. Such instances I have 

 seen on the southern crest of Contentment Hill, where they 

 adjoin well-marked examples of the holocrystalline quartz 

 diorites of the character I have so frequently described as 

 occurring in this district. The schists are so much broken 

 up, that I was not able to find any portions so indisputably 

 in situ that I could ascertain their dip or strike. Their 

 actual contact with the quartz diorites may also be partly 

 due to faulting. Although these rocks have a general 

 resemblance among themselves, I observed on examination 

 that there are two varieties at least — one resembling an 

 indurated and much and minutely contorted argillite, the 

 other having a more pronounced schistose structure. The 

 former variety I found, when examined in a thin slice, to be 

 much silicified, and with the argillaceous material converted 

 into minute scales and flakes of mica, some of which, when 

 examined by a high power, were fibrous. In these micaceous 

 foliations there is black granular material, much of which, 

 but not all, is removed, together with ochreous infiltrations, 

 by digestion of the slice in hydrochloric acid. The quartz 

 foliations are in places peculiar, for the crystalline grains of 

 which they are formed are so arranged as to meet in the 

 plane between the foliations of mica in the manner in which 

 quartz crystals can be seen to form a gangue in some lodes. 



