NEOTECTONICS OF THE DANDALAS RIVER VALLEY, WESTERN TURKEY:INFLUENCES ON STREAMS, SURFACE HYDROLOGY AND HUMAN OCCUPATION IN THE VALLEY OF APHRODISIAS

Within the framework of human interactions with the environment, geoarchaeological investigations of the Aphrodisias Regional Survey focused on the landscape history and surface hydrology of the upper watershed of the Dandalas River, a small, northwest-flowing tributary of the Büyük Menderes River. The Pleistocene history of the valley was dominated by the tectonic uplift of ridges on both sides of the valley during graben formation. Hillslope erosion and fault-related tectonics were the dominant forces acting on the landscape. Changes in the character of the land surface are strongly influenced by both variation in the bedrock lithology and proximity to active faults. Although alluvial fans developed at the base of the uplifted ridges, no significant fluvial sedimentation is evident in the valley bottom. The flat plain on which the ancient city is located is remarkably undissected by modern drainage channels because high on the ridge above the city, a westward-flowing stream diverts water and forms a watershed with channels that dissect the valley floor downstream of Aphrodisias. In the west, localized increases in tributary incision are related to proximity to active faults and the associated nick points in the main stream channel.The landscapes of the valley were stable during the occupation of Aphrodisias from the 2^nd century BC to the 7^th century AD. The unusual surface hydrology of the valley is highly asymmetric owing largely to elevation differences in the valley defining ridges. While over 20 springs are located above 1000 m/sl on the high ridge to the northeast, none are located on the ridge to the southwest that is 600 m lower. Many modern villages and remnants of Roman waterworks are found on the moister northeastern slopes. Limited water resources of the valley necessitated expensive exploitation of extrabasinal water supplies during Roman times.