This study deals with defining of landforms, morphogenetic processes and climatic fluctuations during the continental phases through the Tertiary and Quaternary periods, based on the available data obtained from the geological studies of the Iraqi Jazira Area. The study shows that the present surface of Al-Jazira Area is ascribed to a rejuvenated plateau within the Mesopotamian Depression Province, which originated from influence of destruction and construction processes during two continental phases. The first phase, which started after the sea regression in Oligocene, had produced older plateau, it is characterized by prevailing of denudation processes in humid semiarid climate. The second phase, which started during the initial influence of the last Alpine movements in Late Miocene, gave rise to younger plateau. It is characterized by climatic fluctuations (between wet – arid and semiarid), prevailing of denudation – deposition – chemical weathering and periodical activity of vertical movements, which contributed in development of twenty seven landform assemblages, attributed to seven morphogenetic units of variable origins. The younger plateau witnessed intensive denudation processes and evolution of two peneplains, salt marshes, karsts and surface drainage system.
The study regarded that Tharthar and Chagh Chagh rivers were ancient tributaries of the Euphrates River during Pleistocene – Holocene, which were dried later on, due to neotectonic activities in Sinjar mountain and climatic changes. The developments of ancient rivers, as well as genesis of Tharthar Depression, salt marshes, halcrete and calcrete have been discussed. Moreover, a new geomorphological map for the Iraqi Jazira Area is constructed depending on this study. |