The three southern extremities of the Peloponnesus are thus occupied by high mountains and rocky declivities. The peninsula of Argolis, in the east, is likewise traversed by mountain ranges, which start from Mount Cyllene, similarly to the Gaurias and the mountains of Arcadia. The whole of the Peloponnesus is thus a country of table-lands and mountain ranges. If we except the plains of Elis, which have been formed by the alluvial deposits carried down by the rivers of Arcadia, and the lake basins of the interior, which have been filled up in the course of ages, we meet with nothing but mountains.[16] The principal mountain masses—the Cyllene, the Taygetus, and Parnon—are composed of crystalline schists and metamorphic marbles, as in continental Greece. Strata of the Jurassic age and beds of cretaceous limestone are here and there met with at the foot of these more ancient rocks. Near the coast, in Argolis, and on the flanks of the Taygetus, eruptions of serpentines and porphyries have taken place, whilst on the north-eastern coast of Argolis, and especially on the small peninsula of Methone, there exist recent volcanoes—amongst others, the Kaimenipetra, which M. Fouqué identifies with the fire-vomiting mouths of Strabo, and which had its last eruption twenty-one centuries ago. These volcanoes are, no doubt, the vents of a submarine area of disturbance which extends through Milos, Santorin, and Nisyros, to the south of the Ægean Sea. The sulphur springs which abound on the western coast of the Peloponnesus are, perhaps, likewise evidences of a reaction of the interior of the earth. It is the opinion of several geologists that the coasts of Western Greece are being insensibly upheaved. In many places, and particularly at Corinth, we meet with ancient caverns and sea beaches at an elevation of several feet above the sea-level. It is this upheaval, and not merely the alluvial deposits brought down by rivers, which explains the encroachment of the land upon the sea at the mouth of the Achelous and on the coast of Elis, where four rocky islets have been joined to the land. Elsewhere a subsidence of the land has been noticed, as in the Gulf of {60} Marathonisi and on the eastern coast of Greece, where the ancient peninsula of Elaphonisi has been converted into an island. But even there the fluvial deposits have encroached upon the sea. The city of Calamata is twice as distant from the seashore now as in the days of Strabo, and the traces of the ancient haven of Helos, on the coast of Laconia, are now far inland. * * * * *