“Est ibi mons altus, strictum mare, litus opacum, Hinc hostes citius Anglica regna petunt, Sed castrum Doveræ, pendens a vertice montis, Hostes rejiciens, litora tuta facit.” —DE BELLO HASTINGENSI CARMEN, i. 603. The tract of chalk which forms and gives character to the isle of Thanet and the south-eastern portion of the county of Kent, rises towards the sea to a line of cliffs upon which the promontories of the North and South Foreland and of Dover are the most conspicuous. The cliff line, however, is not continuous. It is broken at intervals by various valleys and gorges, down which the waters from the interior find their way to the sea, producing havens which in former days and for vessels of light burthen were much in request. Of these waters the chief is the Stour, which at no very remote period, near to the present Canterbury, fell into the head of a considerable estuary, the waters of which, guarded by the ancient fortresses Regulbium, Rutupiæ and Lemanis, maintained Thanet as an island, and gave to the trade of the period free access to the interior of the district. This estuary was not exempt from the general tendency to become silted up. Before the Norman Conquest the waters had receded from Canterbury to the parish thence named Stourmouth, and Thanet from an island had become a peninsula. The process of silting up has been since continued, and the mouth of the Stour carried many miles lower. The river, after a very winding course, falls into and in part forms what remains of the ancient English port of Sandwich, opposite to the anchorage known as the Small Downs.