GEOLOGY. 
99 
and readies the coast a few miles north of the Mokihinui river, 
whence, as before, it flanks the central range as far as Lake 
Brunner. ' 
. Although I have termed this granite porphyritic, its structure 
is m many places very variegated; often, as in Mount Newton, 
it becomes finer grained, in other places it is syenitic or horn- 
blendic; sometimes it is dark, from an abundance of mica, and at 
others it presents the appearance of a true porphyry, the com¬ 
pounds becoming so finely grained as to assume that character, 
and large rose-coloured orthoklas crystals being richly scattered 
throughout it. . The contrast between this rich coloured rock and 
the whitish gneiss granite in contact with it, is very striking, and 
I observed, that where the latter is intersected by veins of the 
former, the vein granite is more finely grained. 
Lrom Mount Newton a branch chain extends down the Buller, 
separating the stratified rocks of the Lyell and Brunner 
which lie on its opposite banks. Another branch chain extends 
towards the south between the Brunner range and Mount Mantell, 
and is there associated with trap and amphibolite, the latter of 
which, at the northern end of the Maruia plains, is of great extent. 
The granite reaches its greatest elevation in Mount Mueller, 
which rises from the Maruia plains. It also surrounds the 
Victoria range, and, at the point where the Buhu enters the 
depression, becomes hornblendic. Continuing its course towards 
the south-south-west, it branches off in different directions, all, 
however, having a westerly trend, and between which lie the 
courses of the rivers Inangahua, Waituhu, and Wharau; thence 
it runs towards the Ahaura. 
On the western side of Mount Hochstetter, the Grey leaves the 
main line of the depression, and follows a smaller branch, which 
runs north-north-west, thus uniting it with the granite masses on 
the western side of the range. The same granite is also found in 
the Grey plains, in conjunction with the metamorphic schists, and 
in the high granitic mountains near Lake Brunner, preserving its 
porphyritic structure, as I found from specimens brought to me by 
Mr. Bochfort. Between this granitic net work and the old gneiss 
granite on both sides, we find a great variety of metamorphic and 
sedimentary rocks. On the western side they consist of very 
quartzose mica schists, granulites, old clay slates, quartz schists, 
cherts, and very compact sandstones and conglomerates, the latter 
frequently composed only of angular pieces of old clayslate, 
cemented together by a semi-crystalline silicioim matrix; the 
whole associated with traps, amphibolites, and dioritic jiorphyries. 
The sandstones lie towards the centre of the chain, and I obtained, 
at the eastern foot of the Victoria range, a good section. 
The strata in the mountain gorge, in which. I examined thenq 
consisted of a hard zoned silicious rock, with small veins of 
pegmalite. They had a strike nearly north and souths with a dip of 
