the British-Belgian section formed an island in the Carboniferous, affecting the disposition of coalfields; this is known by names such as the 'London-Brabant Island'. Its bulk had an effect on the geological structure between the Ardennes and the English Midlands by influencing the subsequent crustal folding resulting from the Variscan collision. In Canada, Avalonia comprises the Avalon Peninsula of southeast Newfoundland, southern New Brunswick, part of Nova Scotia, and Prince Edward Island. In the United States, Avalonia consists of northern coastal Maine, all of Rhode Island, and other sections of coastal New England. Development The basement of Avalonia is poorly known, but, based on isotopic analyses, proto-Avalonia most likely evolved together with Carolina about 800 Ma from volcanic arcs far offshore from the supercontinent Rodinia, most likely outboard continental terranes of more obvious West African affinities, such as Cadomia and Iberia. About 650 Ma the Avalonian belt collided with Gondwana. Avalonia originally developed along the shores of Rodinia together with island arcs now found in the Arabian-Nubian Shield (900–700 Ma) and Tocantins in central Brazil (950–900 Ma) and the basement of Avalonia is most likely of the same age. During the Precambrian-Cambrian transition, Avalonia was located in a cool-water environment and even underwent a glaciation. The Moroccan Anti-Atlas range in West Gondwana was, in contrast, characterised by evaporites, evidence of desiccation, and had thrombolites. Avalonia and Gondwana must therefore have been located far from each other during this period. The two did, however, share a geological history from later in the early Cambrian until the mid-Orodovician. Subduction evolved along the shores of Gondwana, which caused Avalonia to rift away and begin its northbound journey towards Baltica during late Cambrian and Early Ordovician. The Rheic Ocean opened behind the Avalonian microcontinents. This independent movement of Avalonia started from a latitude of about 60° South. The eastern end of Avalonia collided with Baltica at 30°S, an event which closed the Tornquist Sea, during the Late Ordovician. In Avalonia, folding, faulting, and volcanism followed – as evidenced in the Welsh Borderland and the Taconic deformation in Laurentia – some or all of which are related to the collision. Plinian eruptions resulted from the subduction beneath Avalonia and produced thick layers of K-bentonite in southwestern Baltica, while the Millbrig eruptions occurred in Laurentia. This Late Ordovician magmatism peaked between 457 and 449 Ma. In the late Silurian and lower Devonian, the combined Baltica and