Thus on the south-west coast of England, in Cornwall, Devon, and Somerset, submarine forests, consisting of the species still flourishing in the neighbourhood, are of such frequent occurrence that, according to Sir Henry de la Beche, ‘it is difficult not to find traces of them at the mouths of all the numerous valleys which open upon the sea.’ Sometimes they are covered with mud or sand, and generally the roots are found in the situation where they originally grew, while the trunks have been horizontally levelled. At Bann Bridge, specimens of ancient Roman pottery have been discovered twelve feet below the level of the sea, and the remains of an old Roman road, now submerged six feet deep, prove that the subsidence of the land has been going on since the times of Julius Cæsar and Agricola. On the east coast the phenomenon is still more striking, particularly in the Wash, that shallow bay between Lincolnshire and Norfolk on whose opposite shores a submarine forest extends, the trunks and stubbles of which become apparent at ebb-tide. On the coasts of Normandy and Brittany we likewise find traces of depression, pointing to some future time when perhaps many a bluff headland, now boldly fronting the ocean, may have disappeared beneath the waves. Huts of the Esquimaux and of the early Danish colonists on the coast of Greenland, now submerged at high tide, could not possibly have been originally constructed in so inconvenient a situation; and at Puynipet, in the South Sea, habitations sunk beneath the water likewise prove a gradual subsidence of the land. On many coasts and islands modern scientific explorers have hewn marks in the rock, to enable future generations to judge of the changes which are slowly but surely altering the configuration of the land and tracing new boundaries to the ocean. Had our forefathers left us similar memorials, we should know much more about the oscillatory movements of the earth-rind than we know now; but, unfortunately, experimental natural philosophy is but of recent date, and the marks chiselled out upon the Swedish rocks in the years 1731 and 1752 are the earliest records by which the chronological progress of elevation or subsidence can be distinctly ascertained. This phenomenon, which has played so important a part in the physical annals of our globe, having once been accurately determined, enables the geologist to explain many facts for which, before it became known, it was impossible to account. We now need not wonder at seeing sea-shells imbedded in the highest mountains or buried hundreds of fathoms under the ground, at alternating layers of marine and sweet-water deposits being frequently storied one above the other, or at originally horizontal strata being now found at every possible angle of inclination.