ortant, as demonstrating that the earliest
inhabitants were familiar with the phenomenon of incursions of the sea.

_Loss of land on the coast of France._--The French coast, particularly
that part of Brittany, where the tides rise to an extraordinary height,
is the constant prey of the waves. In the ninth century many villages
and woods are reported to have been carried away, the coast undergoing
great change, whereby the hill of St. Michael was detached from the
mainland. The parish of Bourgneuf, and several others in that
neighborhood, were overflowed in the year 1500. In 1735, during a great
storm, the ruins of Palnel were seen uncovered in the sea.[442]

CHAPTER XX.

ACTION OF TIDES AND CURRENTS--_continued_.

Inroads of the sea at the mouths of the Rhine in Holland--Changes in
the arms of the Rhine--Proofs of subsidence of land--Estuary of the
Bies Bosoh, formed in 1421--Zuyder Zee, in the 13th century--Islands
destroyed--Delta of the Ems converted into a bay--Estuary of the
Dollart formed--Encroachment of the sea on the coast of Sleswick--On
shores of North America--Tidal wave, called the Bore--Influence of
tides and currents on the mean level of seas--Action of currents in
inland lakes and seas--Baltic--Cimbrian deluge--Straits of
Gibraltar--No under-current there--Whether salt is precipitated in
the Mediterranean--Waste of shores of Mediterranean.

_Inroads of the sea at the mouths of the Rhine._--The line of British
coast considered in the preceding chapter offered no example of the
conflict of two great antagonist forces; the influx, on the one hand, of
a river draining a large continent, and, on the other, the action of the
waves, tides, and currents of the ocean. But when we pass over by the
Straits of Dover to the Continent, and proceed northeastwards, we find
an admirable illustration of such a contest, where the ocean and the
Rhine are opposed to each other, each disputing the ground now occupied
by Holland; the one striving to shape out an estuary, the other to form
a delta. There was evidently a period when the river obtained the
ascendancy, when the shape and perhaps the relative level of the coast
and set of the tides were very different; but for the last two thousand
years, during which man has witnessed and actively participated in the
struggle, the result has been in favor of the ocean; the area of the
whole territory having become more and more c