Illustration: Dynamic processes of the Earth

Global distribution of land masses, shelf area, shallow water and deep oceanic basins at the Permian-Triassic boundary time  (ca. 250 million years ago).  The geographical position of land masses in the geological past is given by paleomagnetic signature preserved in rocks. The age and geometry of oceanic basins can be also deduced from magnetic data if the oceanic crust is still preserved, otherwise is inferred from other geological and geophysical information. The extent of shelf area and shallow water  is reconstructed from paleontological data.