e been traced, says Sir Henry De la Beche, round
the shores of Devon, Cornwall, and Western Somerset. The facts not only
indicate a change in the relative level of the sea and land, since the
species of animals and plants were the same as those now living in this
district; but, what is very remarkable, there seems evidence of the
submergence having been effected, in part at least, since the country
was inhabited by man.[436]

A submarine forest occurring at the mouth of the Parret in
Somersetshire, on the south side of the Bristol Channel, was described
by Mr. L. Horner, in 1815, and its position attributed to subsidence. A
bed of peat is there seen below the level of the sea, and the trunks of
large trees, such as the oak and yew, having their roots still
diverging as they grew, and fixed in blue clay.[437]

_Tradition of loss of land in Cornwall._--The oldest historians mention
a tradition in Cornwall, of the submersion of the Lionnesse, a country
said to have stretched from the Land's End to the Scilly Islands. The
tract, if it existed, must have been thirty miles in length, and perhaps
ten in breadth. The land now remaining on either side is from two
hundred to three hundred feet high; the intervening sea about three
hundred feet deep. Although there is no authentic evidence for this
romantic tale, it probably originated in some former inroads of the
Atlantic, accompanying, perhaps, a subsidence of land on this
coast.[438]

_West coast of England._--Having now brought together an ample body of
proofs of the destructive operations of the waves, tides, and currents,
on our eastern and southern shores, it will be unnecessary to enter into
details of changes on the western coast, for they present merely a
repetition of the same phenomena, and in general on an inferior scale.
On the borders of the estuary of the Severn the flats of Somersetshire
and Gloucestershire have received enormous accessions, while, on the
other hand, the coast of Cheshire, between the rivers Mersey and Dee,
has lost, since the year 1764, many hundred yards, and some affirm more
than half a mile, by the advance of the sea upon the abrupt cliffs of
red clay and marls. Within the period above mentioned several
lighthouses have been successively abandoned.[439] There are traditions
in Pembrokeshire[440] and Cardiganshire[441] of far greater losses of
territory than that which the Lionnesse tale of Cornwall pretends to
commemorate. They are all imp