630 NOTICES OF THE GEOLOGY OF THE EAST COAST OF JOHOHE. 
swer. To the second, the answer can only be derived from a careful 
mineralogical and geological examination of each locality. In the 
southern part of the Peninsula, it will be found that the iron has in 
most cases been acquired from beneath, but in what precise con¬ 
dition originally it is hardly possible in any case to ascertain. Be¬ 
cause, wherever it is visible, it has long been at or near the surface 
of the earth, and, in whatever state of combination it first entered 
the rock, we now only see it highly oxidised.'* There is often clear 
evidence of its having ascended into them in a state of great rarity 
or of sublimation, for in such cases the alterations effected, while 
evincing the presence of great heat, are totally different from those 
that are occasioned by the eruption of dense molten rock. Elec¬ 
trical currents have also left most distinct traces of their agency in 
diffusing it. Great disturbance of the strata, fracture, flexure and 
twisting of lam in re and layers, and conversion of the rock into crys¬ 
tallised quartz, have often accompanied its introduction. The me¬ 
chanical changes that have been effected in the stratified rocks hay¬ 
ing directed us to the platonic basis on which we believe they rest, 
because it rises through them in all directions, we find it is not only 
frequently highly ferruginous in its composition, but is sometimes tra¬ 
versed by ferruginous dykes, which, towards the surface, present the 
same appearances as the more completely ironmasked strata. Last¬ 
ly, a careful examination of these dykes, and of the composition and 
structure of the rock adjoining them, proves that, although oxidation 
has since supervened, they were formed contemporaneously with 
the mass in which they occur, and thus we are led by strict induc¬ 
tion to the conclusion that the elevation, breaking and bending of 
the strata, and the greater part of the quartzose, loteritic and other 
ferruginous changes which they have undergone, had a simple and 
single origin—the same which produced the plutonic mass of the 
Peninsula. The mechanical force of its intumescence gave rise to 
the one series of changes, and the electrical and chemical action 
which attended it to the other. But it would be entirely to super¬ 
sede observation by theory, if we directly attributed every exam. 
p!e of ironmasked rock which we find to this plutonic influence. 
* The decomposition of iron pyrites, and the diffusion of the iron in 
solution, produce a laterilic rock [Ante vol. I. p, 166 .) A similar effect 
Will follow from the decomposition of any other mineral containing a suffi¬ 
cient quantity of iron. The rocks containing such minerals in abundance 
will always retain a lateriticcharactcr from the surface to a certain depth. 
