I 
GEOLOGY. - t)q 
drift formation on its eastern side. There it appeared that the 
a e itself had once extended as far as the conical hill, which 
ormed, whilst still connected with its southern continuation, a 
na urai harrier for the waters. It was therefore evident, from 
lese observations, that the outlet of the lake in former times was 
. 0 wards the east, through the Wairau pass, in the deep depression 
m ® * ,:ls ern chain. It- was without doubt in consequence of 
one ot the great changes in the axis of the island, the downward 
motion of which was towards the west, that the river could no 
onger find a passage through this now upheaved depression, and 
la the waters of the lake, after having risen to a considerably 
higher level, flowed over the barrier formed by the crystalline 
rocks on its western side, and, uniting with the Howard, took the 
course of that river, which had probably already forced its wav 
through the Devil’s Grip. 
I shall have ample opportunity of elucidating the interesting 
subject of the great changes in the level of the country within 
(geologically speaking) recent times, of which so many con¬ 
clusive proofs lie before the eye of the investigator. 
Hie great drift formation is found running from the lake along 
the banks of its outlet to the junction of the latter with the 
Howard. Here we enter upon the granitic zone, which extends, 
with only the interruptions of which I shall speak in the sequel, 
to .Mount Murchison, in which it attains its greatest altitude. 
This granite is the ordinary compound of quartz, feldspar, and 
mica, and is generally of a white colour. It is everywhere asso¬ 
ciated with amphibolites, round which the granite lies, and very 
striking changes occur at the point of contact of these two rocks, 
of which an interesting section is found in the perpendicular cliffs 
on the banks of the Howard, half a mile above the junction of 
that river with the Roto-iti outlet. About a hundred yards from 
the line of contact, the granite becomes hornblendic, and much 
darker, and sends into the amphibolite rock numerous veins, which 
gradually thin out to the breadth of an inch, and become more 
finely grained. The green lustry hornblende schist near the con¬ 
tact is without any stratification, the whole rock consisting ap¬ 
parently of interwoven crystals of hornblende. Receding from 
the granite, these crystals become much smaller, and the feld- 
spathic parts, with grains of quartz equal to them in quantity, 
assume an appearance of coarse stratification. 
It may be as well here to state that, owing to the great masses 
of the drift formation, or alluvium, which almost everywhere cover 
the surface of-the ground, added to the luxuriant growth of vege¬ 
tation, which we find undiminished to the very tops of mountains 
3,500 to 4,000 feet high, it is often extremely difficult to obtain a 
section, except by descending into the gorges of the rivers, which 
I found rather a difficult task, owing to the deep water and almost 
vertical banks, or by ascending to the high rocky mountain tops, 
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