I 
GEOLOGY, 
89 
CHAPTER III. 
« 
GEOLOGY. 
Having treated, in the preceding part of this- report, of the 
physical features of the districts traversed by me, I shall now 
proceed to consider the geological relations of the different moun¬ 
tain chains, both in regard to their age and lithological character, 
and also of the younger formations lying at their bases. In doing 
this I shall again adopt Lake Roto-iti, where I began my field 
work, as my starting point. One mile and a-half from this lake, 
on the northern bank of the stream by which it discharges itself, 
we observe a conical^ hill, which stands about 500 feet above the 
terraced valley at its foot; I could also trace a continuation of the 
mountain on the southern side of the stream, where also the valley 
narrowed very much. This conical hill consists of a granitoid 
rock, a true syenite, but in structure coarser than the syenite of 
Wakapuaka, near Nelson. On its eastern and western sides 
metamorphic rocks are exposed, consisting of dioritic schists, with 
veins of epidosite; on the eastern side of the hill, whence T 
followed them, to the northern end of the lake, these schists are 
changed into quartzose schists. 
As far as the dense covering of drift formation with which this 
part of the country is encumbered would permit, I observed that 
the direction of the plutonic rock was parallel with the high rocky 
chain at its eastern side, ceasing however before it reached the 
northern shores of Lake Roto-roa. These eastern chains, which 
1 ascended in Mount Robert, exhibit the character of true sedi¬ 
mentary rocks. More towards the west, the overlying strata con¬ 
sist of very compact arenaceous sandstones of different colours, 
principally of bluish grey, and occasionally clear and dark olive 
green, dull reddish brown, and blackish, alternating with a com¬ 
pact conglomerate in a hard siliceous matrix, the latter in general 
composed of pieces of clay slates, cherts, quartz, hornstones, and 
epidosites, but without any signs of granites or gneiss amongst 
them. This conglomerate changes again into a homogeneous 
sandstone, in which only angular pieces of clay slate of different 
sizes are sometimes imbedded. 
All these beds are very much disturbed, and are intersected by 
