2 The Delfland region, the genesis of a landscape 4300-3300 BC (fig. 2)
The Delfland region forms part of the coastal area of the present Rhine-Meuse delta. Until the middle of the Atlantic period the balance of the former rapid rise in sea level and the deposition of sediment from the sea and by the major rivers caused the coastline to continually move inland, with the coastal deposits constantly being turned over. In the intracoastal plain behind the narrow, multiply interrupted coastal barrier of those days was a large area of tidal flats. If people ever lived in this landscape, the chances of their occupation remains having survived are minimal. Indeed, no such remains whatsoever have been found in this area. At a certain stage the coastline however stabilised, the process reversed, and the coast steadily expanded on the seaward side. This was the result of fluctuations in the complex balance between the supply of sand along the coast, sedimentation in the basins aligning it and the progressively decreasing rise in sea level (Beets et al. 2000).
For a long time it was assumed that the row of Older Dunes between Hoek van Holland and Leiden represented the oldest surviving coastal barrier, with a date of around 3800 cal BC. In the 1980s, however, a number of deep pits dug during road-construction and urban-expansion projects revealed the sediments of an earlier phase of coastal development buried beneath younger deposits in the Delfland region, implying that this ‘coastal expansion’ actually began a few centuries earlier. The development of the landscape of this area can be followed in considerable detail (fig. 1; Van der Valk 1992, 1996; Cleveringa 2000; Mol 2006).
The oldest coastal barrier in Delfland has been dated around 4350 BC. It extended between an area of shallow water in the coastal plain and the open North Sea. On its seaward side a beach plain with a width of several kilometres then formed, while wash-over deposits were laid down behind it during high tides (Mol 2006). Sand was blown over this plain from the new coastline, resulting in the formation of flat, free dunes.
Our understanding of the layout of these landscape elements, which were on the whole relatively small, but very important for occupation, is limited because they are buried deep beneath the present-day surface. Incidental observations aside, they have actually been mapped in only three fine-meshed detail maps, two of which were made in the context of excavations (Oude Rengerink 1996; Cleveringa 2000, 30; Mol 2006). The dunes were very flat and low, only a few dozen metres wide and not more than 1 to 2 m high. They were relatively small in the west (fig. 3) and somewhat larger in the east, culminating in the dune of Ypenburg, measuring 100 x 750 m.
Fig. 3 Map of an area of around 8 ha in the dune landscape in the strand plain near Wateringse Veld showing four small dunes that were not occupied but were used for unknown purposes. Scale 1:4000. Redrawn after Oude Rengerink 1996.
At first, the sea still had free access to this plain containing the low dunes, but around 3800-3700 BC another coastal barrier with low dunes must have formed along the coast, protecting the plain from the sea. This is the aforementioned line from Hoek van Holland to Leiden. Even so, marine ingressions frequently occurred in these early days, with the salty sea water penetrating the plain from the Meuse estuary in the south or via interruptions in the coastal barrier. In spite of the continuing rise in sea level, the hinterland subsequently became less saline as a result of the closing of the coastline. From then onwards the old coastal plain was for several centuries an accessible and attractive landscape for the Hazendonk communities, between the coast in the west and the vast swamps in the east, between the estuaries of the Meuse in the south and the Rhine in the north, with the dunes affording suitable settlement areas that were dry, if not that high. Occupation came to an end when conditions throughout this area became wetter around the transition from the Hazendonk to the Vlaardingen group, around 3350 BC.
The expansion of the coast with beaches and rows of dunes continued after 3300 BC, and the successors of the Vlaardingen communities were to exploit the new landscapes in a comparable manner, but that is beyond the scope of this article (Groenman-van Waateringe et al. 1968).
The developments outlined above led to the fossilisation in the soil of the Delfland region of a Neolithic landscape that existed for only a short period of time: from around 4000 to 3350 BC. Before that time the landscape consisted of open coast, after that time it changed into swamps. Within this period the natural conditions changed from those of open salt marshes, via grasslands of a ‘green beachplain’ to a reed swamp. From around 3700 BC onwards low dunes afforded suitable settlement areas for people exploiting the rich natural resources in this area.