Nothing authentic is known of the history of Guernsey previously to its annexation to the Duchy of Normandy in the tenth century. The only sources of information as to events which may have occurred before that date are references in monkish chronicles of the usual semi-mythical type, and indications conveyed by cromlechs and menhirs, fragments of Celtic instruments and pottery, and a few Roman relics. It is unfortunate that we are thus precluded from acquiring any knowledge of the development of a people as to whom the soundest among conflicting conjectures seems to be that, coming originally from Brittany, they preserved the purity of the Celtic race through periods when in other offshoots of the same stock its characteristics were being obliterated by the processes of crossing and absorption. If early local records had existed they would hardly have failed to have given minute details of the convulsion of nature which resulted in the destruction by the sea of the forest lands on the northern and western sides of the island, and in the separation of tracts of considerable magnitude from the mainland. Geologists are agreed in assigning to this event the date of March, 709, when great inundations occurred in the Bay of Avranches on the French coast; they are not equally unanimous as to the cause, but science now rejects the theory of a raising of the sea-level and that of a general subsidence of the island. The most reasonable explanation appears to be that the overpowering force of a tidal wave suddenly swept away barriers whose resistance had been for ages surely though imperceptibly diminishing, and that the districts thus left unprotected proved to be below the sea-level—owing, as regards the forests, to gradual subsidence easily explicable in the case of undrained, swampy soil; and, as regards the rocks, to the fact that the newly exposed surface consisted of accumulations of already disintegrated deposits. It is unquestionable that before the inroad of the sea the inlet in the south-west of the island known as Rocquaine Bay was enclosed by two arms, the northern of which terminated in the point of Lihou; on which still stand the ruins of an old priory, while the southern ended in the Hanois rocks, on which a lighthouse has been erected. Lihou is at present an island, accessible only at low water by a narrow causeway; the Hanois is entirely cut off from the shore, but it is a noteworthy fact that the signs of old cart-ruts are visible at spring tides, and that an iron hook was recently discovered attached to a submerged rock which had apparently served as a gatepost; besides these proofs of the existence of roads now lying under the