In these troughs the depth is seldom much less than 3000 fathoms, and this is exceeded in a series of patches to which Murray has given the name of "Deeps."
A third curve, from the south-easternmost promontory of the Peloponnese through Cerigo, Crete, Carpathos and Rhodes, marks off the outer deeps of the open Mediterranean from the shallow seas of the archipelago, but the Cretan Sea, in which depths occur over 1000 fathoms, intervenes, north of the line, between it and the Aegean proper.
In particular Sir John Murray considers that only deeps exceeding 3000 fathoms in depth should be named, and in his charts he has named these deeps after persons whether the individuals thus honoured had themselves discovered or explored the deeps in question or not.
The North African Basin has several deeps with more than 3300 fathoms to the northwest and the south-west of the Cape Verde Islands, but the South African Basin is less deep. In the South Atlantic there is no connexion between the Central Rise and the Antarctic Shelf, for the Indo-Atlantic Antarctic Basin stretches from near the South Sandwich Islands towards Kerguelen with depths exceeding 2500 fathoms and reaching in places 3100.
All the fossil plants and animals of every kind are brought from this continent into a great museum; the latitude, longitude and relative elevation of each specimen are precisely recorded; a corps of investigators, having the most exact and thorough training in zoology and botany, and gifted with imagination, will soon begin to restore the geographic and physiographic outlines of the continent, its fresh, brackish and salt-water confines, its seas, rivers and lakes, its forests, uplands, plains, meadows and swamps, also to a certain extent the cosmic relations of this continent, the amount and duration of its sunshine, as well as something of the chemical constitution of its atmosphere and the waters of its rivers and seas; they will trace the progressive changes which took place in the outlines of the continent and its surrounding oceans, following the invasion§ of the land by the sea and the re-emergence of the land and retreatal of the seashore; they will outline the shoals and deeps of its border seas, and trace the barriers which prevented intermingling of the inhabitants of the various provinces of the continent and the surrounding seas.