o the constant wearing down of the pebbles
by friction, as they are rolled along a beach seventeen miles in length.
But the true explanation of the phenomenon is doubtless this: the tidal
current runs strongest from west to east, and its power is greater in
the more open channel or farther from the land. In other words its force
increases southwards, and as the direction of the bank is from northwest
to southeast, the size of the masses coming from the westward and thrown
ashore must always be largest where the motion of the water is most
violent. Colonel Reid states that all calcareous stones rolled along
from the west are soon ground into sand, and in this form they pass
round Portland Island.[429]

The storm of 1824 burst over the Chesil Bank with great fury, and the
village of Chesilton, built upon its southern extremity, was
overwhelmed, with many of the inhabitants. The same storm carried away
part of the Breakwater at Plymouth, and huge masses of rock, from two to
five tons in weight, were lifted from the bottom of the weather side,
and rolled fairly to the top of the pile. One block of limestone,
weighing seven tons, was washed round the western extremity of the
Breakwater, and carried 150 feet.[430] The propelling power is derived
in these cases from the breaking of the waves, which run fastest in
shallow water, and for a short space far exceed the most rapid currents
in swiftness. It was in the same month, and also during a spring-tide,
that a great flood is mentioned on the coasts of England, in the year
1099. Florence of Worcester says, "On the third day of the nones of Nov.
1099, the sea came out upon the shore and buried towns and men very
many, and oxen and sheep innumerable." We also read in the Saxon
Chronicle, for the year 1099, "This year eke on St. Martin's mass day,
the 11th of Novembre, sprung up so much of the sea flood, and so myckle
harm did, as no man minded that it ever afore did, and there was the ylk
day a new moon."

South of the Bill, or southern point of Portland, is a remarkable shoal
in the channel at the depth of seven fathoms, called "the Shambles,"
consisting entirely of rolled and broken shells of Purpura lapillus,
Mytilus edulis, and other species now living. This mass of light
materials is always in motion, varying in height from day to day, and
yet the shoal remains constant.

_Dorsetshire.--Devonshire._--At Lyme Regis, in Dorsetshire, the "Church
Cliffs," as they are called,