490 
GEOLOGICAL FEATURES OF OUR GLOBE. 
But whilst the lakes of the northern island are chiefly 
formed by subsidence and volcanic agency, those of the 
middle island owe their origin to mountain ranges filled 
with deep valleys, which, having no outlet sufficient to drain 
them, of necessity become lakes, some of which are of consi- 
derable size, Wakatipu being nearly seventy miles long. 
The origin of most lakes is similar to those of New Zealand, 
excepting such as are the evident remains of inland seas, 
most of which are gradually decreasing in size. 
Another grand feature of our globe is the evident increase 
of matter upon its surface, or in other words the thickening 
of its crust ; since the first granitic pavement of the earth 
was formed what wonderful additions have been made, 
stratum superimposed upon stratum, until from the Pri- 
mary to the Pleistocene deposits there is an accumulated 
thickness estimated at little less than fourteen miles ; can 
this vast deposit be satisfactorily accounted for by supposing 
it to have been formed by the debris of that first pave- 
ment, which may have been repeatedly fractured and broken 
up by different convulsions occurring at various epochs 
of the earth's history, or by the vast quantity of matter 
ejected from its bowels by volcanic agency, or by organic 
remains and vegetable deposits, by marine or sedementary 
strata ; however great all these may be there is still to 
account for their being made without diminution of the 
source from whence they were drawn. The same forma- 
tions are still going on to a similar extent, and with the 
same rapidity as at any previous period, neither the earth 
nor the ocean have lost their former fecundity. To take the 
latter, when we consider the immensity of those strata which 
clearly owe their origin to it, the oolite, the cretaceous, 
to say nothing of the mountain limestone, the question must 
arise. Whence this power of production which is ever going 
on without its force being impaired ? It must lead us to 
look for other sources than those derived from our planet. 
Has the sun nothing to do in producing matter upon the 
earth's surface ? Having first imparted light and heat from 
the constant stream of its rays ever flowing upon it, does it 
