generally horizontal position, we are as well assured as that they
were formed at the bottom of seas. But they are always found greatly
inclined in position, tilted up against the slopes of the granitic
masses which are beneath them in geological order, though often
shooting up to a higher point in the atmosphere. No doubt can be
entertained that these granitic masses, forming our principal
mountain ranges, have been protruded from below, or, at least, thrust
much further up, SINCE the deposition of the primary rocks. The
protrusion was what tilted up the primary rocks; and the inference
is, of course, unavoidable, that these mountains have risen chiefly,
at least, since the primary rocks were laid down. It is remarkable
that, while the primary rocks thus incline towards granitic nuclei or
axes, the strata higher in the series rest against these again,
generally at a less inclination, or none at all, shewing that these
strata were laid down after the swelling mountain eminences had, by
their protrusion, tilted up the primary strata. And thus it may be
said an era of local upthrowing of the primitive and (perhaps)
central matter of our planet, is established as happening about the
close of the primary strata, and beginning of the next ensuing
system. It may be called the Era of the Oldest Mountains, or, more
boldly, of the formation of the detached portions of dry land over
the hitherto watery surface of the globe--an important part of the
designs of Providence, for which the time was now apparently come.
It may be remarked, that volcanic disturbances and protrusions of
trap took place throughout the whole period of the deposition of the
primary rocks; but they were upon a comparatively limited scale, and
probably all took place under water. It was only now that the
central granitic masses of the great mountain ranges were thrown up,
carrying up with them broken edges of the primary strata; a process
which seems to have had this difference from the other, that it was