Dokument

Summary:
This is the first time that detailed interdisciplinary research has been carried out along the coasts of Northern Albania. The delta progradation of the river Drini was the focus in an attempt to reconstruct the palaeoenvironmental evolution throughout the Holocene. Our geoarchaeological study comprises 53 vibracorings, obtained in the archaeological area and on the alluvial plains surrounding Lezha, 57 radiocarbon age estimates and several age determinations by diagnostic ceramics. Together with information from historical sources and maps, the results of geochemical, microfossil, and palynological analyses have been combined to create palaeogeographic landscape scenarios for the region around Lezha, beginning with the maximum extent of the Holocene marine transgression. Further scenarios have been generated for the following periods: 4th millennium BC (Middle Neolithic), 2nd millennium BC (beginning of Bronze Age), 6th century BC (Late Iron Age), 4th century BC (Hellenistic times), 2nd century AD (Roman Imperial times), 10th century AD (Early Medieval times) and 1500 AD. The first dramatic changes date back to approximately 5,000-6,000 years ago. Our research shows that the sea had transgressed through the narrow gap between Mali Rrenci and Lezha Hill (Kalaja). The sea reached its maximum inland position between coring sites LIS 27 and LIS 47, north of the town of Balldreni, creating a marine embayment. The river Drini began to deposit its delta sediments into this marine embayment after the peak of the Holocene transgression. At first, the formation and progradation of the delta was dominated by fluvial processes. Radiocarbon age estimates indicate that the river Drini prograded south with several distributaries, forming a Gilbert-type delta during the 4th and 2nd millennium BC. During the Bronze and Iron Ages, the most noteworthy point is the rapid advance of the delta, in the progress of which the marine corridor between Mali Rrenci and Mali Kakarriqi was cut off in the southeast. During the 5th to 4th centuries BC, the marine embayment had ceased to exist, with only a small residual lake to the north of Lissos remaining. The corings within the archaeological area show that the Drini had already prograded past the narrow gap between Mali Rrenci and Lezha Hill when the city was founded in 385/4 BC. Subsequent delta evolution was very slow around Lezha, because the Drini’s previously lesser channel towards the Buna delta became the main river course, diverting much of its sediment. The age estimate from core LIS 43 indicates that the delta of the Drini had progressed for ~ 1.5 km beyond the narrow gorge during the 1st century AD, suggesting a complete reactivation of the river channel past Lissus (as the city was called in Roman times). The following delta growth was controlled by the northbound longshore drift, forming a series of beach barrier – lagoon systems. During Medieval times, especially after the 10th century, environmental conditions changed considerably around Lezha. Radiocarbon ages suggest rapid delta advance northwards in the Ishull Shengjin region during the 10th to 12th centuries. During the following centuries, historical documents play an essential role when attempting to establish a chronology for the growth of the Drini delta. It seems that the westernmost part of the delta developed rapidly after the main river channel changed its direction in the 17th century AD. Extensive swampy environments, especially the Balldreni and Merqia plains and the Drini delta, as well as frequent flooding events have limited settlement expansion in the region. However, this problem was partly solved by the introduction of drainage measures in the 1950s and by the diversion of the main course of the Drini towards the Buna river in 1958. Further human interventions, e.g., the building of dams and hydro power plants in the catchments of the Drini and Mati rivers, resulted in a vastly reduced sediment supply. This in course led to the dominance of erosion processes over accumulation along the coast. Nowadays, there is strong evidence for a continued sea level rise and coastal erosion. Overall, it can be said that the coastal configuration in the research area results from both natural factors such as shifting river courses, continuous general and local tectonic movements, and extreme climatic conditions, as well as human impact in the form of deforestation, and engineering works. It is noteworthy that the delta development in this area is much more complex than it first appeared.

Das Dokument ist im Internet frei zugänglich - Hinweise zu den Nutzungsrechten