Orogenic movements are also known as tectonic revolutions. From the study of the nature and characteristic features of fold-mountains, there, generally, appears to be three stages in an orogenic cycle as:
(i) Initial Stage:
Formation of geosyncline, subsidence and accumulation of sediments.
(ii) Second Stage:
ADVERTISEMENTS:
Sever crusial movements causing folds, faults in sediments and igneous intrusion.
(iii) Final stage:
Upheaval of the deformed sediments to form mountains.
Orogeny causes more crustal deformation in comparison to epeirogeny , even though both the processes together account for all diastrophic activities of the earth.