But we will stop in a because there we
can see a great deal of the roof and the floor. When we land on
the floor of the gallery we shall find ourselves in a kind of
tunnel with railway lines laid along it and trucks laden with
coal coming towards the cage to be drawn up, while empty ones are
running back to be loaded where the miners are at work. Taking
lamps in our hands and keeping out of the way of the trucks, we
will first throw the light on the roof, which is made of shale or
hardened clay. We shall not have gone many yards before we see
impressions of plants in the shale, like those in this specimen
(Fig. 47), which was taken out of a coal-mine at Neath in
Glamorganshire, a few days ago, and sent up for this lecture.
You will recognize at once the marks of ferns (a), for they look
like those you gather in the hedges of an ordinary country lane,
and that long striped branch (b) does not look unlike a reed, and
indeed it is something of this kind, as we shall see by-and-by.
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