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."
in the " Deeps," the Globigerina ooze gradually gives place to red clay.
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.