82 



GEOLOGY OF THE SON VALLEY, ETC. 



was fine-grained, and nearer a basalt than a dolerite. These are the 

 only unaltered minerals. The section shows nothing but a confused 

 mass of irregular felspar granules, uralitic and actinolitic hornblende, 

 epidote chlorite and leucoxene, and even quartz, all of them of 

 secondary origin with the exception of the felspathic groundmass 

 which consists of the fragments of the original prisms. There are 

 some curious pseudomorphs of a mineral, which, judging from the 

 shape of the sections, appears to have been olivine. The original 

 substance is replaced almost entirely by epidote, the remainder being 

 occupied by chlorite. The epidote crystals have begun growing 

 inwards from the boundaries of the crystal, producing an appearance 

 recalling that of the chondri in meteorites. 



c. — Coarser -grained lava. Diabase. 



We may next review some of the volcanic rocks collected from 

 other exposures. They are all closely related to those just described, 

 but present nevertheless some interesting variations. They may be 

 conveniently divided into coarser-grained diabases, and finer-grained 

 melaphyres. 



Amongst the coarser-grained varieties, I shall first mention speci- 

 men ■f^ i the only diabase of this district in which augite has been 

 observed. It occurs north of Jungel interbedded with the purple slates 

 tW"" tit* The diagram Fig. 6 indicates the distribution of the rock. 



Fig. 6. 



i. Red shales sandstone. 2. Plain of Jungel occupied by chlorite schists and 

 volcanic rocks. 3. Horizon of the specimens -^\ and -^ collected a short dis- 

 tance further west. 4. Jasper. 5. Purple slates, ,y ¥ , ?Vo» tet> its- &• Diabase 

 7 y_, 7, Small band of Jasper. 8. Red and green slates with numerous quartz- 

 veins. 

 . ( 82 ) 



