above, as every rock between London
and Birmingham or Exeter has been laid down. That I only assert now.
But I do not wish you to take it on trust from me. I wish to prove
it to you as I go on, or to do what is far better for you: to put
you in the way of proving it for yourself, by using your common
sense.

At the risk of seeming prolix, I must say a few more words on this
matter. I have special reasons for it. Until I can get you to "let
your thoughts play freely" round this question of the superposition
of soils and rocks, there will be no use in my going on with these
papers.

Suppose then (to argue from the known to the unknown) that you were
watching men cleaning out a pond. Atop, perhaps, they would come to
a layer of soft mud, and under that to a layer of sand. Would not
common sense tell you that the sand was there first, and that the
water had laid down the mud on the top of it? Then, perhaps, they
might come to a layer of dead leaves. Would not common sense tell
you that the leaves were there before the sand above them? Then,
perhaps, to a layer of mud again. Would not common sense tell you
that the mud was there before the leaves? And so on down to the
bottom of the pond, where, lastly, I think common sense would tell
you that the bottom of the pond was there already, before all the
layers which were laid down on it. Is not that simple common sense?

Then apply that reasoning to the soils and rocks in any spot on
earth. If you made a deep boring, and found, as you would in many
parts of this kingdom, that the boring, after passing through the
soil of the field, entered clays or loose sands, you would say the
clays were there before the soil. If it then went down into
sandstone, you would say--would you not?--that sandstone must have
been here before the clay; and however thick--even thousands of feet-
-it might be, that would make no difference to your judgment. If
next the boring came into quite different rocks; into a different
sort of sandstone and shales, and among them beds of coal, would you
not say--These coal-beds must have been here before the sandstones?
And if you found in those coal-beds dead leaves and stems of plants,
would you not say--Those plants must have been laid down here before
the layers above them, just as the dead leaves in the pond were?

If you then came to a layer of limestone, would you not say the same?
And if you found th