Metamorphic and Plutonic Rocks at Oraeo, 111 



At (e) in the section Fig. 2, Plate I., there is a close-grained 

 dyke of a dark-greenish colour, lying between the schists, and 

 about three feet in thickness. 



When examined in a thin slice, I observed that it was 

 extremely altered from the usual character of such dykes in 

 this district, and of the original structure but little remained. 

 In parts there had been an extensive deposition of 

 quartz in irregularly-formed concentric radial crystals, 

 forming masses which, when rotated between crossed 

 nicols, showed strong traces of a black cross. Here and 

 there in the portions outside these quartz masses, I 

 could trace the outlines of former lath-shaped crystals 

 of felspar, scattered among numerous groups of grains 

 and tufts of a dark-green mineral, which I did not find to be 

 sensibly dichroic. Were it not for this, I should be inclined 

 to consider it one of the chlorite groups of minerals. Mr. 

 Jas. C. Fraser found in an examination of a sample of this 

 rock, "05 per cent, of boracic acid. All that I can say is, 

 that it probably in its original condition was a diabase 

 porphyrite, and that it seems to have been subjected to 

 metamorphism at the same time with the schists enclosing it. 



Before speaking generally as to the conclusions to be drawn 

 from a consideration of the phenomena observed at the 

 contact of the granites and the mica schists in the two 

 localities now described at Hinnomunjie Morass, it will 

 be well to review slightly different, and yet analogous 

 appearances, in connection with another part of the same 

 contact, which can be studied at Wilson's Creek, at a distance 

 of several miles south east from the locality which I have 

 now described. 



Wilson's Creek rises in the Bo wen Mountains, and in the 

 spur, which runs from it in a north westerly direction over 

 Mount Cook, towards Livingstone Creek. It crosses the 

 line of contact of the granites and schists about a mile and a 

 half above its junction with Livingstone Creek. Thus the 

 upper part of its course is over the metamorphosed schists, 

 and the lower over the granites. 



In Fig. 3, Plate I., I have given a diagrammatic section 

 along that part of its course which covers the most important 

 features. ' 



In the following descriptions, the letters used at the com- 

 mencement of the several paragraphs refer to that section : — 



{a) Spotted schists dipping N. 60", E. at 70°. These beds 

 conform in their strike and in their alternation of quartzose 



