184 The East Anglian Earthquake.
Although the earthquake cannot be distinctly associated
with any known fault or other subterranean disturbance of
the strata, it is essential, in order to complete the present
portion of the subject, to call attention to the nearest known
disturbances, as the connection of these with the earthquake
may with the advance of knowledge become revealed in the
future. Thus Mr. W. H. Dalton has recently pointed out81
the existence of an undulation and fault, throwing down the
Chalk, Beading, and Thanet Beds to the north, underlying
Tiptree Heath. Of this disturbance Mr. Dalton states :—
"Those who care to investigate the origin of the undulation
described above may be interested in hearing that a parallel
undulation has been noticed in the Chalk-ridge above Royston,
with an outward north-westerly dip of 60°; and that the
prolongation of the line of Tiptree Heath coincides, near
Deptford, with a fault bringing up the Chalk through the
Tertiaries, and, in the opposite direction, we have Chalk
coming to the surface in an abnormal way at Shelly (near
Hadleigh) and at Ipswich; whilst farther away, in Suffolk,
other points of disturbance have been noticed along a line
nearly coincident with the Yarmouth branch of the Great
Eastern Railway."
The author expresses his belief that these disturbances are
confined to the upper 1000 feet of the earth's surface, and
are due to lateral pressure in the Chalk; and that the deeper
seated Palaeozoic rocks are not affected. The possible
existence of another disturbance in the Chalk under East
Mersea has already been mentioned (p. 170, note 78).
elicited the opinion that no such alteration occurred, and for this reason
we cannot concur in the view expressed by some geologists, that the
earthquake resulted from the production or extension of a fault in the
London Clay, since a disturbance of the intensity of the present shock
would, as it appears to us, have left some permanent superficial record
under these circumstances.
91 Trans. Essex Field Club, vol. ii., p. 15. In a recent paper by Searles
V. Wood, the younger (Trans. Essex Field Club, vol. iv., p. 76), this
author has expressed the view that the Tiptree Heath boring passed
through an undulation and fold, instead of through a fault. The precise
character of the disturbance does not, however, materially affect the
question, although Mr. Dalton's explanation appears the more probable
to us. The full discussion of this question belongs rather to pure Geology,
and need not be entered into in the present report.