These conclusions derived from the study of the mammalia, are corroborated and supplemented by the evidence of the soundings. As we enter the Straits of Gibraltar (Fig. 129) the Atlantic Ocean shallows, until between Tangiers and Tarifa it is not more than from 270 to 300 fathoms. Between Tarifa and Ceuta the sea measures from 300 to 400 fathoms, and thence, in passing eastwards, suddenly deepens to the extent of over 1,500 fathoms. An elevation of 400 fathoms would be quite sufficient to raise a barrier of land between Morocco and Spain, and to insulate the deep Mediterranean basin from the Atlantic. The soundings between Sicily and Tunis are 260 fathoms; between the former place and Malta, 55 fathoms; between Malta and the African mainland, 34·4 fathoms. An elevation of 400 fathoms would suffice therefore to connect Africa with Sicily, and to insulate the eastern from the western Mediterranean depths. To the east of Sicily the soundings reveal a depth of over 2,000 fathoms, and this deep basin extends as far to the east as Cyprus and Asia Minor. Between Candia and the Peloponese, the sea is 460 fathoms deep. An elevation therefore from 400 to 500 fathoms would allow of the passage of _Hippopotamus Pentlandi_ from Candia to the Peloponese, and thence by southern Italy into Sicily and Malta. I have therefore represented in the map what would be the necessary result of the elevation of the bottom of the Mediterranean to that extent. Two great barriers of land would unite Africa with Spain and Italy, and enable the African mammalia to find their way into the regions north of the Mediterranean Sea. The shallowness of the sea at those two points indicates the existence of the sunken barriers. The African elephant however did not pass far northwards, since it has only been met with in Spain and Sicily. [Illustration: FIG. 129.--Physiography of Mediterranean in Pleistocene Age.] Such a change in level as this would convert the Adriatic into dry land, and cause the islands of the Grecian Archipelago to rise high above the surrounding plains. The 500-fathom line is therefore taken to represent the probable sea margin of the pleistocene age, although in centres of volcanic activity, such as Sicily and the Archipelago, local changes of level, even of greater magnitude, may have taken place. This view of the former elevation of the Mediterranean area to a height of from two to three thousand feet above the present level will go far to explain the remarkable traces of glaciers discovered in Syria, Anatolia, and Morocco. _The Glaciers of Lebanon._