The Grenville Front Tectonic Zone is a geological feature in Eastern Canada that separates the Superior craton from rocks of the Grenville orogeny. It is a large tectonic zone of the Canadian Shield, extending from the northern shore of Lake Huron through Ontario and Quebec to Labrador, a distance of about 1,900 km (1,200 mi).
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Grenville Front Tectonic Zone Wikipedia(Text) CC BY-SA