The
Acadian orogeny is a long-lasting
mountain building event which began in the Middle
Devonian, reaching a climax in the early Late
Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago, with deformational,
plutonic, and
metamorphic events extending into the Early
Mississippian. The Acadian orogeny is the third of the four orogenies that created the
Appalachian orogen and subsequent basin. The preceding orogenies consisted of the Potomac and
Taconic orogeny, which followed a rift/drift stage in the Late
Neoproterozoic. The Acadian orogeny involved the collision of a series of
Avalonian continental fragments with the
Laurasian continent. Geographically, the Acadian orogen extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama. However, the Northern Appalachian region, from New England northeastern ward into
Gaspé region of Canada, was the most greatly affected region by the collision.