A 1912 map of the Indian Ocean in Tiefenkarten der Ozeane mit Erlauterungen
by Max Groll. Note the light-colored (shallower) area between Australia and
Antarctica, an early indication of the continuity of the oceanic ridge system
in the South Indian and South Pacific Oceans. Amazingly, a feature as large as
Ninety East Ridge had yet to be discovered. Plate II, Indian Ocean.