The Denizli graben-horst system (DGHS) is located at the eastern-southeastern converging tips of three well-identified major grabens, the Gediz, the Kucuk Menderes and the Buyuk Menderes grabens, in the west Anatolian extensional province. It forms a structural link between these grabens and the other three NE-NW-trending grabens-the Civril, the Acigol and the Burdur grabens-compri sing the western limb of the Isparta Angle. Therefore, the DGHS has a critical role in the evolutionary history of continental extension and its eastward continuation in southwestern Turkey, including western Anatolia, west-central Anatolia, and the Isparta Angle. The DGHS is a 7-28-km wide, 62-km long, actively growing and very young rift developed upon metamorphic rocks of both the Menderes Massif and the Lycian nappes, and their Oligocene-Lower Miocene cover sequence. It consists of one incipient major graben, one modem major graben, two sub-grabens and two intervening sub-horsts evolved on the four palaeotectonic blocks. Therefore, the DGHS displays different trends along its length, namely, NW, E-W, NE and again E-W.