s a great
manifestation of subterraneous fire, and of exerted force.

The strata in this space consist, in general, of sand-stone, coal,
lime-stone or marble, iron-stone, and marl or argillaceous strata, with
strata of analogous bodies, and the various compositions of these. But
what is to the present purpose is this, that, through all this space,
there are interspersed immense quantities of whinstone; a body which is
to be distinguished as very different from lava; and now the disposition
of this whin-stone is to be considered.

Sometimes it is found in an irregular mass or mountain, as Mr Cronstedt
has properly observed; but he has also said, that this is not the case
in general. His words are: "It is oftener found in form of veins in
mountains of another kind, running commonly in a serpentine manner,
contrary or across to the direction of the rock itself."

The origin of this form, in which the trap or whin-stone appears, is
most evident to inspection, when we consider that this solid body had
been in a fluid state, and introduced, in that state, among strata,
which preserved their proper form. The strata appear to have been
broken, and the two correspondent parts of those strata are separated to
admit the flowing mass of whin-stone.

A fine example of this kind may be seen upon the south side of the
Earn, on the road to Crief. It is twenty-four yards wide, stands
perpendicular, and appears many feet above the surface of the ground. It
runs from that eastward, and would seem to be the same with that which
crosses the river Tay, in forming Campsy-lin above Stanley, as a lesser
one of the same kind does below it. I have seen it at Lednoc upon the
Ammon, where it forms a cascade in that river, about five or six
miles west of Campsy-lin. It appears to run from the Tay east through
Strathmore, so that it may be considered as having been traced for
twenty or thirty miles, and westwards to Drummond castle, perhaps much
farther.

Two small veins of the same kind, only two or three feet wide, may be
seen in the bed of the Water of Leith, traversing the horizontal strata,
the one is above St Bernard's well, the other immediately below it. But,
more particularly, in the shire of Ayr, to the north of Irvine, there
are to be seen upon the coast, between that and Scarmorly, in the space
of about twenty miles, more than twenty or thirty such dykes (as they
are called) of whin-stone. Some of them are of a great thickness; and,