Holocene geologische geschiedenis van Centraal en Noordelijk Noord-Holland

This study deals with litho- and chronostratigraphy of the Holocene in the central and northern part of the Province of North-Holland. The area under discussion can be divided lithostratigraphically into two parts: the area of the beach barriers and tidal inlets (Area B) and the more peaty hinterland (Area A). In the latter Area, four members (Lower Peat, lower member A, middle menber A, upper member A), and in Area B three members (Lower Peat, lower member B, upper member B), were defined in the Westland Formation. Within the entirely clastic lower member A, the Velsen Bed, the Sandy Deposits, the Black Clayand and the Beemster Clay were distinguished. The middle member A comprises beside peat layers (Holland Peat) the clastic Beds A, B, C and D. To the lower member B, the following beds were assigned: the Velsen Bed, Southern Sandy Deposits, Bergen Clay, Northern Sandy Deposits, Older Dune and Beach Sands, Holland Peat and Oer-IJ Deposits. Various beds of Post-2000 B Page were distinguished in the upper members of both areas. The age of the lithostratigraphic units is mainly determined by means of 143 radiocarbon datings. All available information permits to present a detailed paleogeographical reconstruction. The Holocene sedimentary of the area differs in some respects from that of other marine areas in the western and northern part of The Netherlands. These differences are primarily attributed to the typical basin configuration (the Pleistocene surface), dominated by a deeply buried ENE-WSW trending former river valley, in contrast to the mainly N-S orientation of the Top Pleistocene contour lines in the rest of the coastal area. This configuration caused clastic sedimentation to take place initally in the southern part of the basin. About 4900-4800 BP the major part of the marine sedimentation shifted to the north. This change resulted in the deeply eroded Bergen Inlet. The presence and shape of this Inlet has controlled the sedimentary history of this part of The Netherlands during about 1800 C14-years.