Avalonian orogeny

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Avalonian orogeny An episode of mountain building, named after the Avalon Peninsula of Newfoundland, that occurred about 650–500 Ma ago (Cambrian to Ordovician) as a result of rifting (see RIFT) and volcanicity associated with the opening of the Atlantic. Its rocks are found intermittently from Georgia to Newfoundland. See APPALACHIAN OROGENIC BELT.