BY W. N. BKNSON. 605 



of the material of the fragments finely comminuted. The following 

 are the chief types of fragments present : — magnetite-keratophyres, 

 varying in the amount of iron present, more or less trachytic, por- 

 phyritic, massive or hypocrystalline, the last being very vesicular; 

 normal keratophyre, porphyritic or massive, trachytic, or with a 

 wavy flow-structure and occasionally vesicular, coarsely crystalline 

 albitite, partially porphyritic keratopliyre-dolerite, etc. 



The reddened rocks have usually a more ashy appearance, par- 

 ticularly on weathered surfaces. In 1330, the inclusions are mostly 

 fine-grained trachytic keratophyre, with minutely granular augite, 

 and a few more coarsely granular, non-trachytic types are also pre- 

 sent. The base resembles that of 1122; it is very spongy, with a 

 few phenocrysts of albite, and abundant secondary albite and 

 chlorite filling the vesicles. In 13.36, the same feature are 

 present, but parts of the spongy or pumiceous matrix are free 

 from iron-ore, but shade ofT irregularly into strongly ferruginous 

 rock. 



Ha3matitic breccias similar to these, but much more coarsely 

 fragmental, occur on West Gap Hill. In these, there are large 

 areas of finely divided prehnite and epidote. The matrix is rather 

 spongy, a hypocrystalline confusion of felspar-laths, phenocrysts, 

 and microlites, and abundant haematite. The inclusions are of 

 various kinds of keratophyre; the most unusual of these has a tex- 

 ture resembling that of "rhomben-porphyry" ; the others resemble 

 those already described. 



In addition to the red rocks of this character, there are others in 

 which there is no base. The rocks consist entirely of fragments, 

 which are sometimes half an inch in diameter, and are closely fitted 

 together. These {e.g., 1327) include keratophyre; prophyrite con- 

 sisting of large rounded phenocrysts of acid plagioclase in a fine- 

 grained subtrachytic base, in which ar« chlorite-filled vesicles ; por- 

 phyritic spilite, the felspar albite, and the augite changed to chlo- 

 rite; devitrified rhyolite with a well marked flow-structure; mag- 

 netite-keratophyre of varying character, sometimes extremely rich 

 in iron-ore, sometimes porphyritic with crushed and shattered 

 phenocrysts; and felsites with a minutely crystalline or lithoidal 



