Possibly in Caesar's day good natural harbours were still in existence here.
Unfortunately on this part of the coast the study of coastal changes has been involved in a good deal of needless obscurity. Many writers, even geologists, make no clear distinction between loss by submergence and loss by marine erosion. We are told, for instance, that the Goodwin Sands were land about 900 years ago, and that this land disappeared during an exceptional storm. We are sometimes even told that here and elsewhere walls are still visible beneath the sea. Popular writers, to add to the confusion, have some hazy notion that these changes are connected with the existence of submerged forests or "Noah's Woods," and that these again are evidence of a universal deluge. The whole of the arguments are strangely tangled, and we must try and make things a little clearer before passing on. An understanding of the changes which have taken place on this part of the coast is needed for historical purposes, and still more needed if we make a study of the origin of the existing fauna and flora of Britain.
One of the crucial questions, both for the naturalist and archaeologist, is the date at which Britain was finally severed from the Continent. Did this happen within the range of written history, or tradition? Or if earlier, did it take place after or before climatic conditions had become such as we
