Nature & Landscape History Cultural Heritage Visitor Info Addresses Hotels

Historie

Origin. The area has been part of a shallow coastal sea for hundreds of millions of years, but during the various Ice Ages, the southern North Sea area dried up. At the end of the Riss Glacial (200-125,000 years ago), the glaciers deposited lateral moraines at Wieringen and at Texel. After a flooding period, the southern North Sea area dried up again during the next and last Ice Age (Würm Glacial, 70-10 000 years ago) and was completely covered by wind-borne sand deposits. Under the influence of the rising sea level, these sand deposits formed salt marshes and sand barriers ca. 5-10 km north of the current coastline. After a period of further rising of the sea level, the sand barriers moved towards the continent until they arrived more or less at the location of the current coastline, ca. 5000 years ago. During a period of ca. 3000 years low dunes developed on the sand barriers, while large peat moors developed behind them. These moors were often flooded and covered by sea clay.

Taking shape. The relatively low sand barriers were interrupted by large tidal inlets, especially the Vlie (between Vlieland and Terschelling) and the Eems estuary. Because these tidal inlets caused a continuous inflow of salt water, the area remained a "wadden area" (from the Dutch word "waden", meaning "to wade"): a shallow basin with tidal areas, sand banks, salt marshes and channels and a relatively small tidal difference (2-3 m). It was a relatively calm environment in which tiny particles, consisting of young sea clay from the southern North Sea, were deposited. The Wadden area included the Lauwerszee (between Groningen and Friesland), the Middelzee (right through current Friesland) and the Vlie.

Changing patterns. A number of heavy storms in the 13th century caused the Dollard to come into existence in the Eems estuary. The sand barriers were swallowed by the sea and provided sand for a series of young Wadden isles. Due to the storm tide on All Saints' Day in 1570, the island Texel (N15) was permanently divided from Huisduinen (now part of the mainland of Noord-Holland) by the Marsdiep channel. The channels and sand banks have not remained the same over time and they are still changing under the influence of storms, accretion of land and the strong currents; as are the islands. Through erosion on the west sides and accretion of sand on the east sides the islands are subject to constant development.

20th century. The Dutch Wadden Sea has always been an environmentally vulnerable area and since the 20th century it has been threatened by pollution. Three factors contribute to the relatively high level of contamination of the area. Most importantly, many industrial and agricultural activities are located in and around basins of rivers, which flow into the area. Secondly, the North Sea current brings many contaminating materials, especially from the Rhine, into the area. Finally, the Wadden Sea is also affected by atmospheric deposition stemming from the highly industrialised countries in NW and Central Europe.