Two island groups – continental islands and oceanic islands
Two types of islands can therefore firstly be distinguished according to the manner of their formation, continental and oceanic islands; the former being the remaining summits of a continent partially flooded by the sea, the latter as volcanic cones, dormant on the ductile/ malleable ocean floor, soon black and steep, soon sunk under the weight of the constantly growing coral reefs. The relief of the floor of the Indian Ocean (figure 1) already shows the best examples for the three formation types of islands. Mahé, Praslin or La Digue, from the Seychelles group, stand out quickly as the typically first mentioned examples of the continental group: high hill tops cluttered with giant granite blocks, the remains of a sunken continent. Many hundreds of years ago crocodiles lived here, the fact of which shows that this island group was a part of a large continent connected with Africa a long time ago, that geologists call Gondwanaland. The German geologist Alfred Wegener proves that Africa, the Antarctic, India, Australia and South America came from the in the Erdmittelalter (Mesozoic era) broke up super continent Gondwanaland and according to his 1912 theory of continental movement, after they came in their present position, hundreds of continental islands were left quasi as fragments between them. Under the name plate tectonics Wegener’s theses were multiply confirmed and are today generally accepted as basic principles of the history of the origins of the earth.
Ground relief of the Indian Ocean
Figure 1: Relief of the floor of the west Indian Ocean (Troughs and elevations in feet below/over sea level; elevations in brackets: level above the median deep sea floor) Extract taken from the supplement INDIAN OCEAN FLOOR from the magazine National Geographic, October 1967 (1971 reprint) »forward
Find pure nature on the edge of a well functioning civilisation with a piece of land in Nova Scotia, the maritime province in East Canada. We have islands in lakes and at the Atlantic coast, building lots and woodland.