ms of
valleys, but here this is scarcely ever the case. All the villages and
most of the ancient houses are on the platforms or narrow strips of flat
land between the parallel valleys. Is this owing to the summits having
existed from the most ancient times as open downs and the valleys having
been filled up with brushwood? I have no evidence of this, but it is
certain that most of the farmhouses on the flat land are very ancient.
There is one peculiarity which would help to determine the footpaths
to run along the summits instead of the bottom of the valleys, in that
these latter in the middle are generally covered, even far more thickly
than the general surface, with broken flints. This bed of flints, which
gradually thins away on each side, can be seen from a long distance in a
newly ploughed or fallow field as a whitish band. Every stone which ever
rolls after heavy rain or from the kick of an animal, ever so little,
all tend to the bottom of the valleys; but whether this is sufficient
to account for their number I have sometimes doubted, and have been
inclined to apply to the case Lyell's theory of solution by rain-water,
etc., etc.

The flat summit-land is covered with a bed of stiff red clay, from a
few feet in thickness to as much, I believe, as twenty feet: this
[bed], though lying immediately on the chalk, and abounding with
great, irregularly shaped, unrolled flints, often with the colour and
appearance of huge bones, which were originally embedded in the chalk,
contains not a particle of carbonate of lime. This bed of red clay lies
on a very irregular surface, and often descends into deep round wells,
the origin of which has been explained by Lyell. In these cavities are
patches of sand like sea-sand, and like the sand which alternates
with the great beds of small pebbles derived from the wear-and-tear of
chalk-flints, which form Keston, Hayes and Addington Commons. Near Down
a rounded chalk-flint is a rarity, though some few do occur; and I have
not yet seen a stone of distant origin, which makes a difference--at
least to geological eyes--in the very aspect of the country, compared
with all the northern counties.

The chalk-flints decay externally, which, according to Berzelius ("Edin.
New Phil. Journal," late number), is owing to the flints containing a
small proportion of alkali; but, besides this external decay, the whole
body is affected by exposure of a few years, so that they will not break
with clea