GEOLOGY OF NEW ZEALAND. 437 
on the south-east by hilly country, and on the north-west by country 
which is generally low, but broken by the three great volcanic cones,— 
Mt. Egmont (8,280), Ruapehu (9,195), and Tongariro (6,500). The 
rocks also differ much from those of the South Island. The crystalline 
schists of the Takaka system, which are so conspicuous on the south 
side of Cook Straits, suddenly disappear and are quite unknown in the 
North. This sudden change strongly suggests the presence of a fault 
with the upthrow to the south, although it is not possible to prove its 
existence. The rocks of the Oamaru and younger systems are found at | 
nearly equal elevations in both islands, but are higher in the central 
parts of the North Island than elsewhere. The rocks of the Waipara 
and older systems, however, go to considerably greater heights in the 
South than in the North Island. Consequently, the Cook Strait fault, 
if it exists, must have been formed during the interval between the 
Waipara and Oamaru systems, the downthrow being to the north. 
All the rock systems, up to the Hokanui, inclusive, have much 
the same lithological characters throughout New Zealand, and can be 
broken up into series chronologically distinct. They may be called 
“¢continental formations,’ that is, rocks formed on the shore of a 
continent with large rivers. All the rock systems above the Hokanui 
are on the contrary very variable in character in different localities, 
even when not far apart, the only exceptions being a few limestones, 
probably relics of coral reefs. They may be considered as ‘insular 
formations,” that is, as having been deposited round the margin of 
islands from which ran no great rivers. It is impossible, at present at 
any rate, to divide these systems into series which are in all cases 
chronologically distinct. Eruptive rocks cover but a small area in the 
South Island. Isolated exposures of granite occur along the anticlinal 
axis from Paringa River in Westland to Lake Rotoiti in Nelson, and 
in a few other plazes west of the axis, the largest being in the south- 
west of Otago, at Preservation and Chalky Sounds. On the east of the 
axis there are occasional patches of volcanic rocks of younger date. In 
the North Island volcanic rocks are rare on the east side of the main 
range; but on the western side, from the centre of the Island to 
Auckland, they cover more than half the country, and again appear in 
great force further north, between Hokianga and the Bay of Islands. 
There is no granite in the North Island. 
Coal in thin beds is found in the Mataura series, but there are no 
workable seams older than the Matakea series at the base of the 
Waipara system. From the date of the Hokanui system to the present 
day land has existed continuously, and no doubt decaying vegetable 
matter has accumulated in favourable localities. But it was only when 
these accumulations were covered up by deposition that they have been 
preserved. This occurred in two ways, (1) by marine deposits on the 
subsidence of the land, and (2) by lacustrine and fluviatile deposits. 
Consequently we find coals or lignite at the base of the Waipara, 
Oamaru, Pareora, and Wanganui systems covered by marine beds, and 
also we have lacustrine coals and lignites of intermediate ages, but 
which for convenience we may class in each case with the overlying 
series, although there may be an unconformity between them. The 
New Zealand coal measures therefore belong to what I have called 
insular formations. They do not form large basins as in England, 
North America, or Australia, but occur wrapping round hills formed 
