72 The Sedimentary, Metamorphic, 



rare cases the mineral is inclined to form plates resembling 

 an alkali-mica. In this mass there are minute crystals of 

 what I believe to be magnetite. 



The second example is more quartzose, being a mixture 

 of a yellowish micaceous mineral in irregularly-shaped 

 overlapping plates and scales, together with quartz grains. 

 Some of these latter are free from cavities, while others 

 contain them in great numbers, so that one may conclude 

 that there are two generations of them, one being probably 

 original, clastic grains and the other secondary and 

 metamorphic. The rock is much stained by infiltrated iron 

 ore. 



Besides these there are fragments of rock lying on the 

 hillside which have a remarkable amount of a soft silvery 

 mineral in small scales and plates showing on their planes 

 of separation. This rock was too soft and decomposed to 

 admit of being prepared satisfactorily as a thin slice, but the 

 examination which I could make led me to the conclusion 

 that it is a decomposed metamorphosed sediment containing 

 much talc in minute scales on the planes of foliation. 



In the plan which I have laid down for this present work, 

 I now return to the line of section on the western side of 

 the Tarn bo River. It was more convenient to take those 

 rocks together which could be at all considered as being 

 within the sedimentary group, without reference to their 

 position in or near the line of section which I am describing. 

 But in treating of the metamorphic schists, and of the 

 igneous rocks connected with them, this plan would not 

 be satisfactory, for they are so intimately mixed that it 

 would only confuse were I to attempt to select the instances 

 of each group separately. I shall therefore now take the 

 rocks which I noted for observation in the section as they 

 follow each other, leaving to later on the task of summaris- 

 ing the respective and characteristic features of each group. 



In proceeding eastwards towards the junction of the 

 Little River and the Tambo, from the contact with the 

 sediments on the west side of the latter river, no rocks are 

 met with in situ until it is reached, where there are unmis- 

 takable examples of massive quartz-mica diorites in its bed. 

 At the junction of the Little River there is a mass of a red- 

 coloured crystalline granular rock, composed of reddish 

 felspar, quartz, and some chloritised magnesia-mica. This 

 rock is allied to the aplites, which I shall note later on as 

 of very frequent occurrence at Ensay. 



