of rocks. The terrain of Mount Hasan is formed by phreatomagmatic breccias, ignimbrites, lahar deposits, lava domes, lava flows and pyroclastic flow deposits. The pyroclastic flow deposits occur in the form of fans or valley flows, when they were channelled by topography. The northern flanks also feature two debris avalanche deposits with hummocky surfaces. The volcanics of Mount Hasan have been subdivided into a "hot flow" unit, a "Mt. Hasan ashes" unit and into a lava unit. Cinder cones, maars and accompanying lava flows also occur around Mount Hasan, they are part of a basaltic volcano family that forms parasitic vents. These include the cone/maar and a lava flow field at which covers an area of and was produced by fissure vents. Many of the cones around Mount Hasan have been grouped as the Hasandağ-Karacadağ volcanic field. Geology As a consequence of the subduction and eventual closure of the Neo-Tethys and continental collision between Arabia-Africa and Eurasia, Anatolia moves westward between the North Anatolian Fault and the East Anatolian Fault. This movement and the resulting tectonic deformation of Anatolia are responsible for volcanism in Central Anatolia which has been ongoing for the past 10 million years; this volcanism is defined as "post-collisional". Further, volcanism at Mount Hasan has been related to the Tuz Gölü Fault and its intersection with the Karaman-Aksaray faults; the former of these is one of two major fault systems in Central Anatolia which influence volcanism there, and volcanic products of Mount Hasan have been deformed by the fault. The Hasandag fault branches off the Karaman-Aksaray fault and cuts between the two summits of Mount Hasan. The westerly Mount Hasan, central and easterly form a mountain range, which is surrounded by plains and whose summits reach heights of over . Of these mountains, is more heavily eroded compared to the steep cones of Hasan and like is of early Pliocene age. This alignment is congruent with the tectonic patterns of Anatolia, where the collision between Africa and Eurasia follows the same trend. It and to some degree Mount Hasan are also surrounded by a large depression, and the volcanoes of this alignment are separated by faults. Additionally, Mount Hasan forms a volcanic lineament with and the Karapınar Field. The basement in Central Anatolia is formed by magmatic, metamorphic and ophiolitic rocks, the former of which are of Paleozoic to Mesozoic age; it crops out at scattered sites