On the Sand-Pit at High Ongar, Essex. 79
repeated by angles in the streams of the Roding, Stort, Cam,
Great Ouse, Nen, and Welland, as shown on the Ordnance
Map and in angles of the Royston chalk escarpment, so that
radii through the concentric curves of the Canterbury series
would intersect them all.
It was (and is) my view that, governed in its action by the
lateral displacement thus caused, and by the flexures and
fractures which as a consequence took place in the strata
beneath the sea which then covered all this area, that sea as
its bottom gradually emerged into land wrought the principal
part of the denudation to which, in combination with the
flexures, the system of hill and vale over this part of England
is due; though the atmospheric and marine agencies of
subsequent times, especially those of the Glacial Period,
have added to that denudation, and rendered the configuration
thus originally acquired more apparent.
In papers in the 'Quarterly Journal of the Geological
Society,' in which I have had incidentally to advert to this
subject, I have explained that my researches on the Glacial
Beds, during years subsequent to this paper in the 'Philo-
sophical Magazine,' showed me that the view I therein took
—that these curvilinear disturbances originated under the
Glacial Sea—was erroneous; for the position in which I
found the Glacial Beds had shown me that, although the
rectilinear group had originated beneath that sea, the curvi-
linear group had originated beneath an earlier one, which in
all probability was that of the Upper Eocene, or of the
Oligocene Period, which sea must thus have covered this
portion of England to the east of the line before defined ;
though the deposits of the latter have escaped destruction in
Hampshire only, and those of the former are limited to a part
only of the area thus defined. The relation borne by the
rectilinear group of disturbances to the beds formed under
the Glacial Sea is illustrated by Figs. II. to V. of my paper
on the Newer Pliocene Period in England, above referred to.
On the map which accompanies the paper in the 'Philo-
sophical Magazine' I depicted the system of hills which had
resulted from these curvilinear disturbances, calling it a