Again: in the valley of the Mississippi--a tract which is now, it
would seem, in much the same state as central England was while our
coal-fields were being laid down--the earthquakes of 1811-12 caused
large lakes to appear suddenly in many parts of the district, amid
the dense forests of cypress. One of these, the "Sunk Country," near
New Madrid, is between seventy and eighty miles in length, and thirty
miles in breadth, and throughout it, as late as 1846, "dead trees
were conspicuous, some erect in the water, others fallen, and strewed
in dense masses over the bottom, in the shallows, and near the
shore." I quote these words from Sir Charles Lyell's "Principles of
Geology" (11th edit.), vol. i. p. 453. And I cannot do better than
advise my readers, if they wish to know more of the way in which coal
was formed, to read what is said in that book concerning the Delta of
the Mississippi, and its strata of forests sunk where they grew, and
in some places upraised again, alternating with beds of clay and
sand, vegetable soil, recent sea-shells, and what not, forming, to a
depth of several hundred feet, just such a mass of beds as exists in
our own coal-fields at this day.
If, therefore, the reader wishes to picture to himself the scenery of
what is now central England, during the period when our coal was
being laid down, he has only, I believe, to transport himself in
fancy to any great alluvial delta, in a moist and warm climate,
favourable to the growth of vegetation.
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