GEOLOGY. 
117 
probably of the same age as the Davy mountains. Where the 
varan ica breaks through the western side of the central chain, 
ie porphyritic granite seems also to exist, but as the state of the 
weather was such that it necessitated the greatest possible speed, 
A\as unable to ascend any ot those streams, which in summer 
time would have been an easy task. 
h our miles north of the Oparara the granite again reaches the 
coast, and continues, with only little interruption, to the Ihua 
uaroa point North ot the. Oparara, and at the mouth of the 
i\ ei s Haihai and Whakapoai, we find the remains of what was 
probably once an extensive secondary formation, which at the 
mouth of both rivers forms very bold headlands. At the first- 
named place it consists of a shelly tabular limestone, of a greenish 
yellow colour, formed principally of fragments of shells of the 
fragile genera Pecten and Lima, but having imbedded amongst 
them large oysters, which have better resisted the action of the 
Avaves. 
These limestone beds are, as far as I could judge, 200 feet thick, 
and are underlaid by greensands and loose ferruginous sandstones, 
Avhich rest directly on the granite. At the Haihai these strata 
are confined to the coast, but in the valley of the AVhakapoai they 
stretch from tAA r o to three miles inland. It was here, in climbing 
round the sea cliffs at the northern side of the AV lmkapoai river, 
that Mr. S. Maclay found a seam of coal, which is of the same age as 
the coal of Pakawau. Enormous masses of boulders, sometimes 
of great size, are brought down by the torrents, and are carried 
far into the sea, forming tongue-like beds, jutting beyond the 
lines of the rocky cliffs. 
In the same places Ave also meet with tertiary deposits, probably 
of pliocene age, and consisting of loose conglomerates, ferruginous 
sand, and beds of lignite. The granites here found are of various 
kinds, sometimes porphyritic passing into felsite porphyry, and 
sometimes trappean or syenitic, and here and there intersected by 
straight greenstone dikes. In other places veins of apatite, 
fluorspar, and pistazite occur. They have sometimes a tabular, 
and at others a nearly cuboidal parallelopipedoic or polyhedric 
structure. To some angular pieces of these porphyritic rocks, I 
found adhering a coat of silicate of copper. In other places grains 
of oxyde of tin were met with, and had I had time to examine this 
wild region, I am convinced that the discovery of valuable ores 
would have rewarded my researches. The rivers traversing this 
granitic zone bring down, besides granite of all descriptions, great 
quantities of amphibolites and dioritic porphyries, with pieces of 
mica schists, quartzites, and other metamorphic rocks of an 
indistinct character. 
The Kaurangi point projects from the last granitic mountain 
near the coast, which thence strikes inland in a north-easterly 
direction, towards the Aorere valley, low cretaceous hills then 
