[1] The basement beneath Ganderia is unexposed, but the rock of the Green Head Group in southern New Brunswick, the oldest known, contains the Precambrian stromatolite Archaeozoon acadiense,[2] and the Seven Hundred Acre Island Formation in coastal Maine has been dated to c. 670–1230 Ma, similar in age to that of the Amazonian Craton.
The next phase of arc magmatism accompanied by metamorphism occurred at the end of the Precambrian in Newfoundland, New Brunswick and on Cape Breton Island.
[1] Ganderia probably separated from Gondwana near the Cambrian-Ordovician boundary when subduction ceased and a arc-back-arc system developed along a clastic passive margin.
[4] Ganderia and Carolinia were probably connected during the Late Ediacaran and, if so, were collectively separated from Avalonia during the Early Palaeozoic.
[3] When Ganderia was finally accreted to Laurentia during the Late Ordovician and Silurian large scale magmatism accompanied its subduction.