Archaeology: a major tool in the reconstruction of the coastal evolution of Westergo (northern Netherlands)

摘要

Westergo is the name of the coastal area in the northern Netherlands between the former tidal systems of Marne and Middelzee. The area silted up and changed into a salt-marsh area during the Subatlantic (1000 BC-500 AD). The history of seaward migration of the salt marshes in the area has been reconstructed with the help of the archaeologically dated settlements on dwelling mounds (terps). Terps were constructed on the salt marshes when the process of silting had reached the stage of the middle marsh. This zone is flooded less frequently than ca. 50 days per year. The construction of terps during the middle stage of marsh development is indicated by the thickness of the salt-marsh deposits (on which terps were built) and by the diatoms found in these marsh deposits. The oldest phase of terp settlement on the marshes of Westergo is dated between the Late Bronze Age and Early Iron Age (ca. 600 BC) and is found in the southern part of Westergo (the "old land"). During the next period (500 BC-500 AD) the "funnel-shaped tidal basin" in the northern part silted up to the supratidal level. The middle marsh zone in the funnel-shaped basin expanded during this period (1000 years) by ca. 5 km at the western and eastern sides of the basin and by ca. 10km in the central part. This implies a mean marsh extension in this former tidal basin of ca. 5-10 m per year. In this paper, a reappraisal of the nature and genesis of the salt-marsh ridges of the northern Netherlands is presented.