242 
THE GEOLOGY OF NEW ZEALAND. 
heaves the whole, allows time for another growth of forest, 
when all again subsides, and the same gradual process is 
repeated. The traveller along the coast has only to read these 
pages of the Earth’s history, which are unfolded for his 
instruction, and reflect upon them ; but this is only a page, 
and one which is visible : another remains still to be examined. 
The sure indications of coal, which further along the coast 
crops out, betoken a series of more ancient convulsions. 
Modern subsidings of the earth’s surface to such an extent 
are, happily, rare, although, doubtless, many occur in places 
where there are none to see or to make them known.* To 
what is the present exemption from such terrible visitations 
in these islands to be attributed ? but to the volcanoes which 
extend through them. They have poured forth their streams 
of molten rock: they have filled up the cracks and crevices of 
the earth’s crust: they have strengthened the deficiencies of 
its framework, and hindered the recurrence of future convulsions. 
Small, perhaps, as the extent of these islands now is, to what 
it formerly was, these streams of lava stop further encroachments 
on the land. Thus, while the ocean is rapidly gaining on 
some parts of the south-west coast of the Northern Island, 
the promontory of Cape Egmont presents its front to the 
surge, and withstands its fury; strengthened by numerous 
streams of lava, which are plainly seen like buttresses at every 
headland from that Cape as far as the Sugar-loaf rocks, they 
form so many impassable barriers to the further inroads of 
the ocean. 
That these islands have been disrupted by former convulsions, 
is seen by a single glance at the map; but the period is, per¬ 
haps, as far back as the general disjunction of the continental 
line of which New Zealand is only a surviving link. 
A few words remain to be said of the rocks of New Zealand. 
In the North, the basis is whin, above which is an ochreous 
clay, containing bright particles of magnetic iron, which 
* The natives have several traditions of lands and islands having; been sub- 
merged. There is one of an island near Taranaki, which had a very large'Pa 
upon it, suddenly sinking with all its inhabitants during the night; of another 
at Patea, and of an island in Cook’s Straits, called Titapua, thus disappearing. 
