Chronology of the coastal plain development during the Holocene in West Belgium

Borehole evidence, correlated by means of sedimentary environmental interpretation, linked with age dates from basal and intercalated peat layers yielded the chronology of the development of the coastal plain of West Belgium. The sea level was close to at least - 18 m (NAP) at about 8400 B.P. and the formation of tidal flats started as from 8100 B.P. The rapid sea- level rise caused the deposition of only tidal sediments. At 7000 B.P., however, a first peat growth initiated although only restricted in valley-like depressions in the pre-Holocene surface. But between ca 6400 B P. and 2200 B.P. the entire area was characterized by alternating peat growth and deposition of tidal sediments, reflecting a decrease in the rise of the sea level. Highly favourable conditions for peat formation prevailed between ca 5200 B.P. and 2200 B.P. resulting in an apparent continuous peat accumulation for nearly 3500 and 2200 14-C years in respectively the landward and seaward part of the area. After ca 2000 B.P. drastic changes in the environmental conditions resulted again in the formation of only tidal deposits