2 Some Points in Geology. 
free to act their part again,—if we knew all this, we should indeed 
be complete geologists, standing on our highest point! But what 
can we see now? Dowe see granite mountains, of recent date, 
‘piercing through the older mountains, and pushing them aside all 
around,’ fancying that ‘they have risen like giants even above the 
clouds, raised by the power of the hidden fires’? Notso. We have 
learnt of late, that, in accordance with the general structure of the 
globe, continental areas may be regarded as portions of the earth’s 
crust, crumpled at their edges by the lateral pressure effected by 
the sea-areas being dragged downward by contraction; and that 
this crumpling has produced elevated ridges or mountains, together 
with changes in the strata; limestones becoming marble; coal being 
purified into anthracite and graphite, and, may be, diamond ; sands 
changed to quartzites; clays and muds to slates and schists; nay, 
even gneiss and granite coming out from the further process of 
squeeze and heat and change of moist strata; the former structure 
lost, but the original elements still remaining; the silica and alumina, 
and their associated alkalis, metals, and so forth, being rearranged 
in crystalline and often gem-like forms. From another point of view 
we see horizontal and unaltered beds at first slightly undulated, 
then thrown into curves and sharp folds,their substance altered, even 
porphyries and trap-rocks here and there representing some of their 
layers, their fossils vanishing, their bedding scarcely traceable and 
crossed by planes of cleavage, as we go up the mountain-gorge. 
But if we do not lose sight or thought of the great curvatures and 
folds, we can still track out the comparatively thin and once bedded 
mass, a few hundred feet in thickness, now folded and crumpled, into 
elevated ridges of altered rock, and passing into a compressed heart 
of gneiss and granite,—the axis of the range, or nearly so. And this 
may altogether be not even of Paleozoic age; but Triassic beds, 
Jurassic, Cretaceous, or even Tertiary, may form the mass. Many 
a range of so-called primeval granite, gneiss, and slate, lapping one 
over the other successively for hundreds of thousands of feet, or of 
upright ‘primary schistus,’ miles across, will exhibit to the geolo- 
gist of to-day only many times repeated folds of an altered set of 
strate ; nor will their furthest change, or granitic form, be taken 
either for primeval or intrusive granite: and, whilst the latter may 
still be found, the former, or the hypothetical granite of a cooling 
globe, becomes a myth. 
Take America for example: we cannot follow Rogers across the 
Alleghanies, Hector across the Rocky Mountains and Vancouver, 
Whitney across the Californian ranges, Wall through Venezuela, 
Trinidad, and Jamaica, and D. Forbes across the Andes, without 
seeing the true relations of granitic and schistose rocks to strata. 
Sir William Logan’s accurate sections of Canada, when published, 
will show pre-eminently how gneissose rocks are bedded rocks ; quartz 
and silicates (felspar, mica, hornblende, &c.) replacing the sands and 
clays of early deposits: old shingle-beds are among them still, and 
their great marble-~beds are now known to be, partly, at least, of 
organic origin, like other limestones,—the foraminiferal Eozodén 
