amiss here. It will be noted by the traveller from the north that the
opposing line of heights in Surrey have their steepest face (or
"escarpment") on the south side, while the Sussex Downs have theirs on
the north. A further peculiarity lies in the fact that the river
valleys which cut across each range from north to south are opposite
each other, thus pointing to the probability that the fracture which
caused the clefts was formerly continuous for fifty miles through the
great dome of chalk which extended over what is now the Weald. The
elevation of this "dome," caused by the shrinking and crumpling of the
earth's crust and consequent rise of the lower strata, was never an
actual smooth rise and fall from the sea to the Thames valley; through
the ages during which this thrust from below was in progress the crown
of the dome would be in a state of comparatively rapid disintegration,
and it is because of this that we have no isolated masses of chalk
remaining between the two lines of hills. The highlands called by
geologists the "Forest Ridge" are in the centre and are the lowest
strata of the upheaval; they are the so-called Hastings sands which
enter the sea at that town half-way between Beachy Head and Dover
cliffs. North and south of this ridge is the lower greensand, forming
in Sussex the low hills near Heathfield, Cuckfield and Petworth, and
which reaches the sea south and north of Hastings. It was at one time
supposed that the face of the Downs originally formed a white sea cliff
and that an arm of the sea stretched across what we know as the Weald,
but the simpler explanation is undoubtedly the correct one.

[Illustration: WANNOCK.]

The Downs themselves are composed of various qualities of chalk; some
of such a hard, smooth and workable material that, as will be seen
presently, the columns in some of the Downland churches are made from