File:The Quarterly journal of the Geological Society of London (12712048644).jpg

1855..
NICOL GRAMPIANS.
547
porphyry .p) is quarried, and a si-
milar bed is seen on the coast near
Cove. At this village also a large
mass of granite .g) is quarried.
As we approach Aberdeen, granite-
veins become more and more nu-
merous, until near Girdleness, im-
mediately south of the Dee, they
almost form the predominant rock.
The most remarkable points in
this section are, — the position of
the clayslate and mica-slate, and
the relation of the metamorphic
strata to the Old Red Sandstone.
In regard to the former, the clay-
slate, usually considered as the
newer, and undoubtedly the less
altered, rock, appears to dip under
the older mica-slate. My impres-
sion is, that this is truly the case,
and that, in proceeding along the
coast, there is an ascending series
from the less metamorphic to the
more metamorphic rock. But this
could not be the original position
of the masses ; and I can only
explain the phsenomenon by sup-
posing that a complete inversion of
the beds on the southern margin
of the chain has taken place. In
the north they regain their ori-
ginal position, dipping away from
the great granitic axis, or rather
foundation, of the country. The
change of inclination also seems to
be effected in a peculiar manner by
the highly convoluted mica-slate
and gneiss strata folding up, as
it were, on themselves, and thus
pushing out the upper and exterior
beds, as if by great intruded wedges
of rock. It is thus an instance in
our own country of the fan-shaped
stratification so often noticed in
the Alps.
How far this inversion extends
along the border of the mountains
has not been determined. Near
the western termination of the for-
mations, as well seen along the
Gare Loch on the Firth of Clyde,
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