106 
TIIE GEOLOGY OE HELSOH. 
Ill tlie same line, farther south, lies a third group of volcanic 
hills, forming the peninsula of Otago. 
These three points doubtless indicate a line of volcanic 
action, running parallel to the great middle range or backbone 
of the Middle Island, on the eastern side of it. A closer 
examination, especially of the Otago Province, would no doubt 
furnish ns with more and similar examples of volcanic hills on 
that line. It is remarkable, that—whilst the parallel zones of 
volcanic action on the Northern Island (the Tongariro zone, 
the Auckland and the Bay of Islands zone) all run on the 
western side of the backbone range between Wellington and 
the East Cape—the great volcanic line of the Middle Island 
takes the eastern side. 
Many peculiarities in the physical features of the Middle 
Island, and also many interesting facts respecting the earth¬ 
quakes in New Zealand, can be explained by the different 
position of the line of volcanic action in the two islands. 
Reserving, however, for my future publications this interest¬ 
ing subject, which I regret I have not time to enter upon, I 
will, in conclusion, offer a few 
GENERAL REMARKS. 
In the earlier geological era of New Zealand, we may 
assume that both islands were connected, and that one back¬ 
bone ran continuously from the South Cape to the East Cape. 
In the present map of New Zealand the integrity of this back¬ 
bone is broken at Cook’s Straits, and a closer inspection will 
show that there has been not only a simple break of continuity, 
but a lateral dislocation. Cook’s Straits is, to use a miner’s 
expression, a true fault. It is evident, from the rocks being 
of the same geological formation, that at one period the 
Pelorus ranges were a continuation of the Wellington ranges. 
The position of the strata in the eastern ranges of Nelson 
proves, that whilst the Northern Island seems to have remained 
stationary, some gigantic force has pressed the great mass of 
the Middle Island to the westward. The given description of 
the tertiary formation, extending between the ranges far up 
the valleys, sounds, and bays leading towards Cook’s Straits on 
both sides, farther proves that the first act of this great 
conuvlsion ol nature took place prior to the tertiary period, 
