Book excerpt: The classical Appalachian, Caledonian, Hercynian, and Mauritanide orogens are now only segments of a once-continuous Paleozoic mountain belt which has been fragmented during Mesozoic-Cenozoic formation of the North Atlantic Ocean. These segments are major parts of the countries surrounding the North Atlantic - most of which are members of NATO. The aim of this NATO conference was to evaluate these fragments in terms of their pre-Mesozoic positions, and to attempt a synthesis of their geologic evolution on an international and orogen-wide scale. Geologists who have studied these scattered remnants have been separated by both geography and discipline. Orogen-wide syntheses have beeen attempted in the past by individuals who are specialists not only in discipline but also in geography; therefore, these attempts have not been satisfactory to everyone. This conference brought together the foremost specialists in different disciplines from each country. They attempted to teach other specialists, not only in their own fields, but in other disciplines, about regional variations and particular problems. The resulting international cross-fertilization, both within and between speciaLties, enriched individual workers and helped to provide a multi-disciplinary overview of the orogen.