A 3200 km long, Palaeozoic, orogenic belt extending from Newfoundland to Alabama and interpreted as the consequence of the closure of the Iapetus Ocean. Extensions of the belt along strike include the Caledonian orogenic belt (see caledonian orogeny) in north-western Europe, now separated by the Atlantic Ocean. The deformation in the Appalachian belt ranges from late Precambrian to Permian, divided into four major orogenies (Avalonian, Taconic, Acadian, and Alleghanian), with the transport of thrust-nappes predominantly north-westwards. Seismic reflection profiling by COCORP has supported, at least for the southern Appalachians, recent interpretations of a thin-skinned tectonic style in which a few kilometres’ thickness of highly deformed material has been thrust westward for at least 200 km.