By Nicole Mortillaro, CBC News Ottawa, March 19, 2017
Researchers have found traces of Earth's crust in the Canadian Shield dating back 4.2 billion years, when our planet was in its infancy.
Earth's composition is unlike any other known planet or moon, with rocky crusts forming and moving over the surface. Over time, this has forced older evidence of such crusts — both oceanic and continental — deep below the surface.
http://www.cbc.ca/news/technology/earth-original-crust-canadian-shield-1.4028576