EVOLUTION OF COASTAL DRAINAGE OF ESSEX. 49
It would appear that the river plan during the period in
question was a normal system consequent upon the slopes then
probably existing. In this river plan we have the origin of the
physiographic pattern already mentioned; the middle broad
Essex valley was beginning to take shape and a series of secondary
consequent river valleys were becoming apparent in the Pant,
Brain and Chelmer. Attention should also be drawn to the fact
that, at this time and in the later stages, the main river had a
tendency to migrate to the south-east. This implied uniclinal
shifting provides some explanation for the previously mentioned
asymmetrical slopes. Tendring, it will be observed, is outside
the area of the main river system both in the past as in the
present.
Following this stage of the Essex riverine development came
the so-called "Winter Hill" period, which probably occurred
at the beginning of Pleistocene times. It would appear from the
evidence of the gravels on the peneplane at the close of this
period, that the Winter Hill stage was synchronous with the
beginning of the Pleistocene glaciation. The ice-sheet of the
period probably extended almost to the main stream of this
river system (fig. 5).
(To be continued.)