Abstract: The Neotectonic period in Eastern Turkey hasstarted a compressive regime in the Middle Miocene.This compressive regime has caused E - W thrusting which has dips to north and south, NE - SW striking left lateralfaults, NW - SE striking right lateral faults and N - S trending fractures and related volcanism.Eastern Turkey was almost a peneplain at the beginning of the Neotqctonic period. The structural developmentand volcanism in this period have changed the peneplain morphology. Geomorphologic development was in the formof ridges and basins which were formed from anticlines and synclines. Rivers flowing in N - S direction cut antecedentvalleys but rivers flowing in E - W directions formed meanders in coincidence with the morphology. This simplemorphological structure is controlled and complicated bythrusting, strike slip faulting, extension and volcanism. Asa result of these events ridges and narrow alongated basins lying roughly in the E - W direction were formed andthese basins gained low altitudes compared with the altitudes of the ridges. These basins are defined as inter - mourtain basins and a typical example for them is the Mus basin in Eastern Turkey. It is thought that the region has undergone crustal shortening and thickening and subsequent rising. This geologic and geomorphological developmentof Eastern Anatolia implies that the region is now at the stage of mountain building.