calamine, have all, in this manner, been found in
coal.

There remains now only to consider those bituminous strata of fossil
coal in relation to that change of situation which has happened more
or less to every stratum which we examine; but which is so much better
known in those of coal, by having, from their great utility in the arts
of life, become a subject for mining, and thus been traced in the earth
at great expense, and for a long extent.

Coal strata, which had been originally in a horizontal position, are now
found sometimes standing in an erect posture, even almost perpendicular
to the plane in which they had been formed. Miners therefore distinguish
coal strata according as they deem them to approach to the one or other
of those two extremes, in terming them either flat or edge seams or
veins. Thus, it will appear, that every possible change from the
original position of those strata may have happened, and are daily found
from our experience in those mines.

But besides the changed position of those strata, in departing from the
horizontal line or flat position in which they had been formed, there is
another remarkable change, termed by miners a _trouble_ in the coal. The
consideration of this change will further illustrate the operations of
nature in placing that which had been at the bottom of the sea above its
surface.

Strata, that are in one place regularly inclined, may be found bended,
or irregularly inclined, in following their course. Here then is a
source of irregularity which often materially effects the estimates
of miners, judging from what they see, of those parts which are to be
explored; and this is an accident which they frequently experience.

But, without any change in the general direction of the stratum, miners
often find their coal broke off abruptly, those two parts being placed
upon a higher and lower situation in respect to each other, if flat
beds, or separated laterally if they are edge seams. This is by miners
termed a _slip, hitch_, or _dyke_.

These irregularities may either be attended with an injected body of
subterraneous lava or basaltes, here termed whin-stone, or they may not
be attended, at least apparently, _i.e._ immediately, with any such
accident. But experienced miners know, that, in approaching to any of
those injected masses of stone, which are so frequent in this country,
their coal is more and more subject to be troubled.

As there is, in this country of