asonable
suppositions. For, _first_, The strata that attend coal, whether the
sandstone or the argillaceous strata, commonly, almost universally,
abound with the most distinct evidence of vegetable substances; this
is the impressions of plants which are found in their composition.
_Secondly_, There is much fossil coal, particularly that termed in
England clod coal, and employed in the iron foundry, that shows
abundance of vegetable bodies in its composition. The strata of this
coal have many horizontal interstices, at which the more solid shining
coal is easily separated; here the fibrous structure of the compressed
vegetable bodies is extremely visible; and thus no manner of doubt
remains, that at least a part of this coal had been composed of the
vegetable bodies themselves, whatever may have been the origin of the
more compact parts where nothing is to be distinguished.

The state in which we often find fossil wood in strata gives reason to
conclude that this body of vegetable production, in its condensed state,
is in appearance undistinguishable from fossil coal, and may be also in
great quantity; as, for example, the Bovey coal in Devonshire.

Thus the strata of fossil coal would appear to be formed by the
subsidence of inflammable matter of every species at the bottom of the
sea, in places distant from the shore, or where there had been much
repose, and where the lightest and most floatant bodies have been
deposited together. This is confirmed in examining those bodies of
fossil coal; for, though there are often found beds of sand-stone
immediately above and below the stratum of the coal, we do not find any
sand mixed in the strata of the coal itself.

Having found the composition of coal to be various, but all included
within certain rules which have been investigated, we may perceive in
this an explanation of that diversity which is often observed among the
various strata of one bed of coal. Even the most opposite species of
composition may be found in the thickness of one bed, although of very
little depth, that is to say, the purest bituminous coal may, in the
same bed, be conjoined with that which is most earthy.

Fossil coal is commonly alternated with regular sand-stone and
argillaceous strata; but these are very different bodies; therefore,
it may perhaps be inquired how such different substances came to be
deposited in the same place of the ocean. The answer to this is easy; we
do not pretend to trace