On the Sand-Pit at High Otigar, Essex. 79 
repeated by angles in the streams of the Boding, Stort, Cam, 
Great Onse, Nen, and Welland, as shown on the Ordnance 
Map and in angles of the Boyston 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 tbe 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 Y. 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 
