Avalonian and Cadomian Geology of the North Atlantic aims to provide region by region syntheses of those terranes which are believed to have once formed part of the Late Proterozoic Avalonian-Cadomian belt. The belt originally comprised a series of volcanic arcs and marginal basins formed during the period c. 700-500 Ma ago, producing a range of calc-alkaline volcanics and intrusives and marginal basin sediments partly founded on continental basement rocks. Originally about 9000 km long, the belt is made up of a number of terranes later separated by the Caledonian orogeny (c. 500- 400 Ma), Variscan orogeny (c. 325 Ma), and the recent opening ofthe Atlantic Ocean (c. 70 Ma). The rocks therefore are w located on both sides of the Atlantic, as far apart as Florida and Czechoslovakia. A possible modern analogue for the Avalonian-Cadomian belt may be the present-day Western Pacific margins. We believe that a synthesis such as this provides the basis for correlation of the timing of events and hence improves our understanding of the underlying tectonic framework of the belt. This book developed from the recognition of, first, our own lack of kwledge of contemporaneous events outwith Armorica, and, second, the likelihood that other researchers working on individual areas or terranes do so in relative isolation. We have therefore commissioned chapters from researchers considered to be experts on their own particular areas.