Geomorphological observations concerning the evolution of the Basin of Athens

Abstract

Tectonism is an important element in the determination of the present landscape of Greece. It has shaped and is shaping the numerous highlands and depressions and consequently settlement patterns of the country. One such area is the Greater Athens region, a triangular basin, opening to the sea in the southwest and surrounded by four mountain masses. The presence of an old planation surface on the surrounding mountains; of thick lateritic soils in the basin overlain by Miocene and Pliocene marls, marly limestones, sands and conglomerates; Pleistocene fluvio-torrential deposits; alluvial fans; and fluvial and marine terraces, enabled the authors to put together the Tertiary and Quaternary tectonic and geomorphic evolution of the Greater Athens area. The paleogeographic evolution goes back to a probable mountainous topography before the Miocene with near tropical climatic conditions. In the Early Miocene, the breaking up of the highland area and the formation of today's basin begins or has already begun. During the Late Miocene, a transgression of the sea occurs, particularly in the western half of the basin. This is followed by regression, erosion and Late Pliocene transgression. During the Neogene and Quaternary we have continuous fluvio-torrential deposition intercalating with marine sediments. In the Quaternary, the tectonic activity in the area slowly subsides and climate, particularly in the late Pleistocene and Holocene and eustatism, especially along the coastal zone, affect more readily the depositional and erosional regime and geomorphic processes.