It is stated in the second report of the commissioners on the bogs of
Ireland, that _three_ distinct growths of timber, covered by three
distinct masses of bog, are discovered on examination. But whether these
morasses were at first formed by the destruction of whole forests, or
merely by the stagnation of water in places where its current was choked
by the fall of a few trees, and by accumulations of branches and leaves,
carried down from the surrounding hills, is a question.
Professor Davy is of opinion, that in many places where forests had
grown undisturbed, the trees on the outside of the woods grew stronger
than the rest, from their exposure to the air and sun; and that, when
mankind attempted to establish themselves near these forests, they cut
down the large trees on their borders, which opened the internal part,
where the trees were weak and slender, to the influence of the wind,
which, as is commonly to be seen in such circumstances, had immediate
power to sweep down the whole of the internal parts of the forest. The
large timber obstructed the passage of vegetable recrement, and of earth
falling towards the rivers; the weak timber, in the internal part of the
forest after it had fallen, soon decayed, and became the food of future
vegetation.
Mr. Kirwan observes, that whatever trees are found in bogs, though the
wood may be perfectly sound, the bark of the timber has uniformly
disappeared, and the decomposition of this bark forms a considerable
part of the nutritive substance of morasses. Notwithstanding this
circumstance, tanning is not to be obtained in analysing bogs; their
antiseptic quality is however indisputable, for animal and vegetable
substances are frequently found at a great depth in bogs, without their
seeming to have suffered any decay; these substances cannot have been
deposited in them at a very remote period, because their form and
texture is such as were common a few centuries ago. In 1786 there were
found, seventeen feet below the surface of a bog in Mr. Kirwan’s
district, a woollen coat of coarse, but even, network, exactly in the
form of what is now called a spencer; a razor, with a wooden handle,
some iron heads of arrows, and large wooden bowls, some only half made,
were also found, with the remains of turning tools: these were obviously
the wreck of a workshop, which was probably situated on the borders of a
forest. The coat was presented by him to the Antiquarian Society. These
circumstances countenance the supposition, that the encroachments of men
upon forests destroyed the first barriers against the force of the wind,
and that afterwards, according to sir H. Davy’s suggestion, the trees of
weaker growth, which had not room to expand, or air and sunshine to
promote their increase, soon gave way to the elements.
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