After a century and ft half it began to recede rather than to advance.
Islands are frequent; the banks recede and become lower until, after 50 m., they stand almost level with the water.
It was not Stephens fault that the boundary of England did not permanently recede from the Tweed and the Soiway to the Tyne and the Ribble.
As we recede in time we find the extinct representatives of many of these orders approximating more and more closely to a common generalized type, so that in a large number of early Eocene forms it is often difficult to decide to which group they should be assigned.
The first two predominate earlier, and gradually recede before the last-named.