Thus the seaward ends were continuously occupied by sea, from the time when the oak-forest sank right on into historic times, and over this deeply buried oak-forest we only find alternate layers of silt and sea-sand. Evidence of the later submerged forest, however, is not entirely wanting, for the submerged wooden bridge or causeway of Pentuan must belong to the period when the trees seen on the foreshore elsewhere were flourishing well above high-water mark.
The submerged forests seen on the foreshore in western Cornwall are so like those exposed elsewhere that there is no need for a full description, were it not that they have become so connected with ancient legends of Lost Lyonesse, a country which is supposed to have joined the Land's End to the Isles of Scilly somewhere about the date of King Arthur and Merlin. To what extent these stories are due to observation of the submerged forests and of the rapid waste of land in Mount's Bay, supplemented by a vivid Celtic imagination, which saw "the tops of houses through the clear water," is doubtful. Legend may assist, as is shown in a later chapter (p. 120). One thing is clear, the alluvial flat of Mount's Bay, under which the submerged forest lies, formerly extended much further seaward; and old writers mention the tradition that St Michael's Mount formerly rose as an isolated rock in a wood. As far as can be calculated from its known rate of encroachment, the sea cannot have
