论文
Antoni Canicio, Carles Iba ez
The existing scientific literature about the Ebre delta states that it formed in very recent times (mostly since the middle ages) and that in Roman times it was an estuary. This belief is based on erroneous interpretation of historical data, rather than on scientific evidence. We present the first data about the position of early coastlines based on radiocarbon dating. The evidence proves the existence of the Ebre delta as much as 5 750 a BP. Another early coastline that dates to 3 045 a BP has also been identified. Using this information and other sources such as old maps and present day bathymetry of old eroded deltaic lobes, we constructed the first evolutionary sequence of the Ebre delta during the Holocene. Cartographic information was carefully and critically assessed in the process of selecting those maps that are coherent with geomorphic structures. Details about the evolution of deltaic lobes are only given for the last millennium. The development of the southern lobe was at its maximum about 1 ka BP. By the 16th century the lobe had already been strongly reshaped (maximum retreat about 8 km) after the abandonment of the old river arm. At that time the Ebre delta already had developed a surface similar to that of the present. The maximum penetration of the lobe into the sea (about 25 km) is clearly indicated in bathymetric maps. During the 17th century the northern lobe reached its maximum extent (also about 25 km), and at the end of that century the central lobe (the one presently active) started to form, reaching its maximum growth (again about 25 km) by the beginning of the 20th century.
