nd exactly with each other; secondly the occurrence of a
submarine ridge, called "our Lady's Sand," extending from shore to shore
at no great depth, and which, from its composition, appears to be the
original basis of the isthmus; thirdly, the identity of the noxious
animals in France and England, which could neither have swum across, nor
have been introduced by man. Thus no one, he says, would have imported
wolves, therefore "these wicked beasts did of themselves pass over." He
supposes the ancient isthmus to have been about six English miles in
breadth, composed entirely of chalk and flint, and in some places of no
great height above the sea-level. The operation of the waves and tides,
he says, would have been more powerful when the straits were narrower,
and even now they are destroying cliffs composed of similar materials.
He suggests the possible co-operation of earthquakes; and when we
consider how many submarine forests skirt the southern and eastern
shores of England, and that there are raised beaches at many points
above the sea-level, containing fossil shells of recent species, it
seems reasonable to suppose that such upward and downward movements,
taking place perhaps as slowly as those now in progress in Sweden and
Greenland, may have greatly assisted the denuding force of "the ocean
stream," [Greek: Potamoio mega sthenos Ocheanoto].

_Folkstone._--At Folkstone, the sea undermines the chalk and subjacent
strata. About the year 1716 there was a remarkable sinking of a tract of
land near the sea, so that houses became visible from certain points at
sea, and from particular spots on the sea cliffs, from whence they could
not be seen previously. In the description of this subsidence in the
Phil. Trans. 1716, it is said, "that the land consisted of a solid stony
mass (chalk), resting on wet clay (gault), so that it slid forwards
towards the sea, just as a ship is launched on tallowed planks." It is
also stated that, within the memory of persons then living, the cliff
there had been washed away to the extent of ten rods.

Encroachments of the sea at Hythe are also on record; but between this
point and Rye there has been a gain of land within the times of history;
the rich level tract called Romney Marsh, or Dungeness, about ten miles
in width and five in breadth, and formed of silt, having received great
accession. It has been necessary, however, to protect it from the sea,
from the earliest periods, by embankment