The concept of the geosyncline has been a controversial subject ever since it was proposed. It appears, however, that in the “new global tectonics,” geosynclinal theory could be rationalized into a sound unified concept of geosynclinal genesis and evolution. Starting with continental rifting, or at least stretching, or on continental margins not clearly affected by lithosphere plate movements, an open series of tensile geosynclines will form as extensional trough-ridge complexes or continental terraces, or both, skirted by continental aprons (rises). Then with subsequent ocean closing, or with crustal flexuring and decoupling, a closed series of compressional mio-eugeosynclinal ridge-trough complexes forms, followed by exogeo-synclines and molasse basins to complete a geo-tectonic cycle. In addition to these mature mother geosynclines (orthogeosynclines), which develop through the complete cycle to give rise to Alpinotype mountains, there are also immature geosynclines (parageosynclines), which form in interrupted geotectonic cycles to produce only Germanotype mountains. Endless variations in modes of geosynclinal evolution and mountain building, due to retarded or prolonged geosynclinal opening or to similarly affected flexuring and decoupling in the closing stage, are expected within a geotectonic cycle. These variations are influenced by the vagaries of lithosphere plate movements, as well as those of polycyclic intercontinental and intracontinental geosynclines, some of which are unaffected by lithosphere plate movements.