Holocene sea-level changes along the Mediterranean coast of Israel, based on archaeological observations and numerical model

Abstract

Local sea-level curves reflect global eustatic changes, regional isostatic adjustments of the crust to changing ice and ocean volumes and tectonically controlled crustal movements. In this study, we evaluate the relative contribution of each of these factors to the Holocene sea-level curve of the Mediterranean coast of Israel. We use archaeological data as constraints on palaeo sea levels and we then compare the observational limits with isostatic models for sea-level change across the region. The isostatic model includes the contribution arising from the relative minor increase in ocean volumes for the past 6000 years due to residual melting of ice sheets, the effect of the changing shape of the ocean basin, the time dependence of shorelines as sea-level changes and the changing surface area occupied by ice sheets. Differences, if significant, between the observed and predicted change are interpreted as being of tectonic origin. The archaeological observations and the model sea-level curve, along the Mediterranean coast of Israel were found to be generally consistent and any discrepancies lie within the uncertainties of both values. Our model predicted that 8000 years ago sea level at the Israel coast was at about −13.5±2 m, whereas the archaeological data place it at −16.5±1 m. By 7000 BP the predicted level has risen to about −7±1 m consistent with the archaeological evidences. According to both observations and predictions sea level was still lower than −3 to −4.5 m at 6000 BP and remained below its present level until about 3000–2000 BP. The comparison between the model sea-level curve and the archaeological observations also enable to conclude that the average rate of vertical tectonic movement for the last 8000 years, at the Carmel coast, Israel, has been less than 0.2 mm/year.