i Baba in the tale of the
Forty Thieves--but some word or two which Madam Why will teach us, and
forthwith a hill will open, and we shall walk in, and behold rivers and
cascades underground, stalactite pillars and stalagmite statues, and all
the wonders of the grottoes of Adelsberg, Antiparos, or Kentucky.

Am I joking? Yes, and yet no; for you know that when I joke I am usually
most in earnest. At least, I am now.

But there are no caves in chalk?

No, not that I ever heard of. There are, though, in limestone, which is
only a harder kind of chalk. Madam How could turn this chalk into hard
limestone, I believe, even now; and in more ways than one: but in ways
which would not be very comfortable or profitable for us Southern folk
who live on it. I am afraid that--what between squeezing and heating--she
would flatten us all out into phosphatic fossils, about an inch thick;
and turn Winchester city into a "breccia" which would puzzle geologists a
hundred thousand years hence. So we will hope that she will leave our
chalk downs for the Itchen to wash gently away, while we talk about
caves, and how Madam How scoops them out by water underground, just in
the same way, only more roughly, as she melts the chalk.

Suppose, then, that these hills, instead of being soft, spongy chalk,
were all hard limestone marble, like that of which the font in the church
is made. Then the rainwater, instead of sinking through the chalk as
now, would run over the ground down-hill, and if it came to a crack (a
fault, as it is called) it would run down between the rock; and as it ran
it would eat that hole wider and wider year by year, and make a swallow-
hole--such as you may see in plenty if you ever go up Whernside, or any
of the high hills in Yorkshire--unfathomable pits in the green turf, in
which you may hear the water tinkling and trickling far, far underground.

And now, before we go a step farther, you may understand, why the bones
of animals are so often found in limestone caves. Down such
swallow-holes how many beasts must fall: either in hurry and fright, when
hunted by lions and bears and such cruel beasts; or more often still in
time of snow, when the holes are covered with drift; or, again, if they
died on the open hill-sides, their bones might be washed in, in floods,
along with mud and stones, and buried with them in the cave below; and
beside that, lions and bears and hyaenas might live in the caves below,
as we know