East Antarctic Shield

The East Antarctic Shield is a cratonic rock body covering about 10.2 million square kilometers, roughly 73 percent of the continent of Antarctica. It is made up of ancient igneous and sedimentary rocks that have been deformed and metamorphosed and intruded by granites, with basement ages running from the Precambrian through the Ordovician. Almost the entire shield lies buried beneath the East Antarctic Ice Sheet, which averages 2,200 meters thick and reaches as much as 4,700 meters in places, and it is separated from West Antarctica by the roughly 3,500-kilometer Transantarctic Mountains. Internally it divides into an extensive central craton, the Mawson Craton, occupying most of the continental interior, plus several marginal cratons exposed along the coast, and it played a central part in the formation and breakup of the ancient supercontinents Rodinia, Gondwana and Pangea over the past billion years.