Plate Tectonics

 The theory (what we think) says the Earth's crust (outer layer) is made up of 7 large pieces of crust called plates.

windows2universe.org (image)

 http://www.cotf.edu/ete/modules/msese/earthsysflr/plates1.html

 http://www.kidsgeo.com/geology-for-kids/0043-plate-tectonics.php

http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml