BY E. M. JOHNSTON, F.L.S. 69 



point on the slope of the hill shows the folio wiyg section in a 



downwtii'd direction : — 



ft. in. ft. in. 



Grey flaggy sandstones, with occasional carbona- 

 ceous streaks 60 



Shaly parting 1 



Coal, slaty and anthracitic 2 8 



Coal glance, brilliant lustre 8 to 10 



Oreyish-black arenaceous and carbonaceous clod, 



verytrace 4 to 18 



Dark brownish clod and shales, full of impres- ] tt v n 

 sion of Vertebraria australis, Ganga77iopteris > , i " -i^ ^^^ 

 spathulata ) ^^^cKness. 



It is probable that the seam extends to the Garden Island 

 Creek vicinity, where, judging from the prevailing dip, it 

 may yet be found possibly at a much greater depth. It is 

 interesting to observe that the writer also found what appears 

 to be the sandstones of the system abutting against the 

 greenstone axis at about the same vertical height on the 

 eastern slope above Long Bay. 



The study of the rocks about Port Cygnet presents very 

 many interesting featui-es. The low rounded hills in the 

 neighbourhood of the township ai-e, for the most part, com- 

 posed of an intrusive felspar porphyry, there largely used for 

 road metal. The felspar porphyries are very beautiful and 

 extremely variable. The triclinic crystals of felspar with 

 microscopical striated surfaces are most variable in size, 

 colour, and abundance. The crystals are grey, white, yellow, 

 or flesh-tinted, embedded in a pasty mass ; sometimes normal 

 in size, and thickly and uniformly distributed, at other times 

 large and sparsely distributed. Intimately associated with 

 the more pronounced forms of felspar porphyries is to be 

 found a close-grained dark-greenish metamorphic rock of a 

 chloritic appearance, streaked and marbled with greenish- 

 white lines and blotches; nests of pyrites occurring in great 

 abundance in the centres of the larger greenish-white 

 blotches. 



At Lymington, in the same locality, gold in an alluvial 

 form has been worked with more or less success in the 

 valleys associated with this porphyritic rock, and it is a 

 question of much interest to ascertain by careful experiment 

 whether the pyrites of the metamorphic rocks associated with 

 the porphyry may not also be auriferous. Apparently no 

 other rocks of an auriferous character are now to be found in 

 the vicinity. 



Traversing these felspar porphyries and associated meta- 

 morphic rocks southward in the direction of the lower coal 



