I told
Sedgwick of the fact, and he at once said (no doubt truly) that
it must have been thrown away by some one into the pit; but then
added, if really embedded there it would be the greatest
misfortune to geology, as it would overthrow all that we know
about the superficial deposits of the Midland Counties. These
gravel-beds belong in fact to the glacial period, and in after
years I found in them broken arctic shells. But I was then
utterly astonished at Sedgwick not being delighted at so
wonderful a fact as a tropical shell being found near the surface
in the middle of England. Nothing before had ever made me
thoroughly realise, though I had read various scientific books,
that science consists in grouping facts so that general laws or
conclusions may be drawn from them.
Next morning we started for Llangollen, Conway, Bangor, and Capel
Curig. This tour was of decided use in teaching me a little how
to make out the geology of a country. Sedgwick often sent me on
a line parallel to his, telling me to bring back specimens of the
rocks and to mark the stratification on a map. I have little
doubt that he did this for my good, as I was too ignorant to have
aided him. On this tour I had a striking instance of how easy it
is to overlook phenomena, however conspicuous, before they have
been observed by any one. We spent many hours in Cwm Idwal,
examining all the rocks with extreme care, as Sedgwick was
anxious to find fossils in them; but neither of us saw a trace of
the wonderful glacial phenomena all around us; we did not notice
the plainly scored rocks, the perched boulders, the lateral and
terminal moraines.
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