The submergence of the barriers, and the constitution of the Mediterranean as we find it now, have probably taken place but a short time ago, from the geological point of view, though we know that for the last 3,000 years the coast-line has been on the whole unchanged, except from the silting out of the sea by the sediment of rivers, such as the Po, and the elevation and depression of small areas by volcanic energy, as at Santorin. The physical character of the shores testifies to the truth of this view. “On entering the Straits of Gibraltar,” Mr. Maw writes, “from the Atlantic, a notable change takes place in the aspect of the coast. Cape St. Vincent, on the Atlantic coast, presents a bold line of cliffs to the sea, and bluff cliffs extend many miles towards the Straits; but as soon as these are passed, a change of coast-form takes place, which must be noticeable to every observer. Cliffs on the sea-board become the exception, and the general line of the coast is merely a shelving under the sea of the general hill-and-valley system of the land, the sea running up all the depressions, and the land elevations spreading out into the sea with scarcely any abrupt cliff-line of demarcation. The uneven sea-bottom of the Straits seems to be a continuation of the contour of the adjacent land, consisting of rolling alternations of hill and valley, which must have received its conformation by subaerial agencies.” “Corsica, and the adjacent islands of Elba, Capraja, and Monte Christo, are also remarkable for the absence of cliffs, and are wanting in those abrupt escarpements separating land and water which are so abundant on our own coasts. Their aspect is that of mountain-tops rising out of the sea, suggesting to the eye the seaward prolongation of their subaerial contour of sloping hillsides and river-cut valleys, as though the sea had not stood sufficiently long at its present level to excavate an escarpement. The deep intersecting bays that occur along the coast from Marseilles to the Riviera suggest the same conclusion, the undulating land surface spreading down to the water’s edge, and the deep bays running up the intervening valleys, which must have had an origin common with that of their landward prolongations.” It is impossible to shut our eyes to the full force of this reasoning. The present aspect of the Mediterranean is, geologically speaking, a thing of yesterday. _Changes of Level in the Sahara coincident with those in the Mediterranean._