[2] The Parautochthon is a band running parallel to the Grenville Front, which varies in width from Labrador to northeastern Georgian Bay on Lake Huron.
[2] The Canadian Shield spans much of northern Quebec, which is primarily underlain by the Superior Craton, a 160-mile thick section of stable continental crust formed beginning 4.03 billion years ago.
In the northwest and at the northern tip of the Ungava Peninsula is the large Churchill Craton, which extends into Labrador and Nunavut as the eastern extent of the Canadian Shield.
[3] During the Taconic orogeny that began the formation of the Appalachian Mountains, amphibolite, mica schist and other metamorphic rocks formed a belt running down the Gaspe Peninsula to Sherbrooke.
Quebec experienced intense erosion during the past 2.5 million years of the Quaternary, which often mobilized older rocks, such as Proterozoic granite boulders found offshore in the moraines which formed parts of the Magdalene Islands.