164 The East Anglian Earthquake.
considerations which have just been advanced, that if any diffe-
rence of effect resulted from the situation of the buildings on
the drift or on the clay, that the maximum destruction would
have occurred on the latter ; and we were not surprised there-
fore, on arriving at Colchester, to find that many of the resi-
dents had formed the opinion that the chief damage was con-
fined to the clay. Our own survey enabled us to fully confirm
this belief that the maximum amount of destruction had
occurred on the clay-areas, a conclusion in which we are sup-
ported by Mr. G. H. Kinahan, P.G.S., of the Geological
Survey,67 and Mr. "William Cheetham,68 who also visited the
earthquake district.
But although it happens that the buildings chiefly affected
were situated on the clay, as at Peldon and Abberton, a
certain amount of damage occurred on the drift, as at West
Mersea and Colchester, and on the alluvium at Wivenhoe.
We are disposed to conclude that there is in fact no distinct
evidence at present in favour of any differential action
between the clay and the drift as regards their effects upon
the vibrations, and that the greater destruction occurring on
the former was a pure geological accident arising from the
fact, for which there is a considerable amount of converging
evidence, that the initial blow was given beneath the London
Clay in the Peldon-Abberton district. The larger amount of
destruction on the clay thus appears to be geological, and not
simply dynamical; and the only question that can be legiti-
mately raised is whether the damage would have been equal,
greater, or less, if, with the same disturbance, the villages
most seriously injured had been situated on a thick bed of
drift. The answer to such questions as this will no doubt be
67 Mr. Kinahan's notes on the earthquake have since been published in
the ' Proc. of the Roy. Dublin Society' for 1884, p. 318. I will take the
present opportunity of acknowledging the assistance which I have
received from the map of the superficial Geology (W. H. Dalton's, 48,
S.W.), prepared by Mr. Kinahan during his visit so as to show the distri-
bution of the damage, and kindly placed at my disposal for the
preparation of this report.
68 Mr. Cheetham's paper was read before the Leeds Geological Asso-
ciation on October 30th, 1884, but has not yet been published. I am
indebted to the author for having kindly allowed me to see his MSS.