DOVER Straits, the narrow channel between Dover and Calais, which separates our island from the opposite continent. Britain is supposed by many to have been once peninsular, the present straits occupying the site of the isthmus which joined it to Gaul. "No certain cause (says Mr Pennant *) can be given for the mighty convulsion which tore us from this continent; whether it was rent by an earthquake, or whether it was worn through by the continual dashing of the waters, no Pythagoras is left to solve the fortuna locorum:"
Vidi ego, quod fuerat quondam solidissima tellus
Effre fretum.
But it is most probable, that the great philosopher alluded to the partial destruction of the Atlantica insula, mentioned by Plato as a distant tradition in his days. It was effected by an earthquake and a deluge, which might have rent asunder the narrow isthmus in question, and left Britain, large as it seems at present, the mere wreck of its original size. The Scilly isles, the Hebrides, Orkneys, Shetlands, and perhaps the Feroe islands, may possibly be no more than fragments of the once far-extended region. I have no quarrel about the word island. The little isthmus, compared to the whole, might have been a junction never attended to in the limited navigations of very early times. The peninsula had never been wholly explored, and it passed with the ancients for a genuine island. The correspondence of strata on part of the opposite shores of Britain and France, leaves no room to doubt but that they were once united. The chalky cliffs of Blaneux between Calais and Boulogne, and those to the westward of Dover, exactly tally: the last are vast and continued; the former short, and the termination of the immense bed. Between Boulogne and Folkestone (about six miles from the latter) is another memorial of the junction of the two countries; a narrow submarine hill, called the Rip-raps, about a quarter of a mile broad, and ten miles long, extending eastwards towards the Goodwin sands. Its materials are boulder-stones, adventitious to many strata. The depth of water on it, in very low ebbs during spring tides, is only fourteen feet. The fishermen from Folkestone have often touched it with a fifteen feet oar; so that it is justly the dread of navigators. Many a tall ship has perished on it, and sunk instantly into twenty-one fathoms water. In July 1782, the Belleisle of sixty-four guns struck, and lay on it during three hours; but, by starting her beer and water, got clear off.
"These celebrated straits are only twenty-one miles wide in the narrowest part. From the pier at Dover to that at Calais is twenty-four. It is conjectured, that their breadth lessens, and that they are two miles narrower than they were in ancient times. An accurate observer of fifty years remarks to me, that the increased height of water, from a decrease of breadth, has been apparent even in that space. The depth of the channel at a medium in highest spring tides is about twenty-five fathoms. The bottom either coarse sand or rugged scars, which have for ages unknown resisted the attrition of the currents. From the straits both eastward and westward is a gradual increase of depth through the channel to a hundred fathoms, till soundings are totally lost or unattended to. The spring tides in the straits rise on an average twenty-four feet, the neap tides fifteen. The tide flows from the German sea, passes the straits, and meets, with a great rippling, the western tide from the ocean between Fairleigh near Hastings and Boulogne; a proof that, if the separation of the land was effected by the seas, it must have been by the overpowering weight of those of the north."