BY W. N. BENSON. 721 



spar-fragments, with a very little kaolin, chlorite, and magnetite. 

 Fragments of trachyte and granite, and, occasionally, large, broken 

 crystal-grains. 



Jasper: [M.B., 120]. Pebble in conglomerate; composed of 

 very fine, even-grained quartz, and abundant biotite; no signs of 

 radiolaria are visible. 



Pebbles of igneous rocks: all the rhyolites described in the ear- 

 lier portion of this chapter (p. ,). Many varieties of trachyte 

 and rhyolite-tuff in various stages of decomposition. Several kinds 

 of granitic rock, e.g., M.B., 8, a rock composed of phenocrysts of 

 felspar and quartz, in a coarse-grained, granophyric matrix, with a 

 little magnetite, sphene, and chlorite after biotite. Also, M.B., 

 347, a granodiorite with included fragments of a finer-grained rock 

 (microdiorite), differing from its host only in grain-size, the rarity 

 of quartz, and the abundance of the ferromagnesian minerals. It 

 consists of hornblende, magnetite, sphene, and oligoclase, with a 

 little orthoclase. 



Aplites and quartz or felspar porphyries are abundant. Rocks 

 of a basic character, however, are notably absent. 



I am indebted to Mr. A. B. Walkom, B.Sc, for sections of many 

 of these rocks, and for comparison of the rhyolites with those he 

 has studied from Pokolbin, 200 miles to the south. 



(7) The Permo-Carboniferous rocks are sandstone, in Bowling 

 Point and in the Nan de war region. The former consists of abun- 

 dant, rounded or subangular, fairly fresh grains of plagioclase, 

 with smaller, angular grains of quartz; fragments of keratophyre 

 (?) and spilite in a fine-grained, felspathic matrix, coloured with 

 chlorite, limonite, etc. There are no signs of straining or crush- 

 ing( Slide, N.T., 204). 



Bocks of Uncertain Origin. — A most remarkable rock occurs, 

 forming a large, oval patch in the serpentine, at the head of Yel- 

 low Rock Creek, south of Crow Mountain. It consists of a white, 

 granular matrix, containing long, green, prismatic (? ) crystals. 

 Microscopically [M.B., 231, and 262], it is seen to consist chiefly of 

 zoisite and clinozoisite. The former is the more abundant. It has 

 a well marked, prismatic habit and cleavage, and characteristic, 



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