Elevated aseismic structures more or less isolated in the oceans have been often interpreted as microcontinents. They are particularly numerous in the Indian Ocean: Crozet Plateau, Kerguelen Plateau, Madagascar Plateau, Seychelles Plateau. Geophysical data show that some of these plateaus are true microcontinents (continental crust) while others are probably only elevated oceanic structures. Other examples are shown in the North Atlantic: The Jan Mayen Ridge in the Norwegian Sea and the Rockall Plateau. Sedimentation on the margins of true microcontinents are often characterized by well defined syn-rift deposits and pelagic post-opening sediments with few elastics due to the isolation from important land-masses.