Orogenic belts and their parts

Summary Geological tectonic literature is at present confused. For instance, in the existing literature the terms geosyncline and orogenic belt are often used almost synonymously. This usage is misleading and obscures the fact—demonstrated with respect to several orogenic belts—that orogenic belts are structural units of a larger size than geosynclines and may involve a series of geosynclinal furrows. Consequently in discussing geotectonic concepts a proper nomenclature of orogenic belts and their divisions has to be employed; certain proposals are therefore made. It is also significant that, at least within Phanerozoic time, orogenic belts originated repeatedly in the same sections of continental crust. Such relationships are indicated by both geological and geochronological investigations. The Caledonian belt of the British Isles, for instance, is divided into several parts each affected by separate orogenic movements. The boundaries between these parts are often delineated by major fault lineaments. Else-where such deep fundamental faults are held to be important in the siting and evolution of orogenic belts.