Origin
There is little evidence of continental crust prior to 3.5 bya, and there was relatively rapid development on shield areas consisting of continental crust between 3.0 and 2.5 bya. All continental crust ultimately derives from the fractional differentiation of oceanic crust over many eons. This process has been and continues today primarily as a result of the volcanism associated with subduction.
Read more about this topic: Continental Crust
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