The palaeoenvironment of eastern West

The palaeoenvironment of eastern West-Frisia:
a critical review
W. K. van Zijverden
Palaeogeography, West-Frisia, Bronze Age, environment
In the second half of the twentieth century, several large-scale excavations were carried out in West-Frisia. A habitation model
was developed based on the results. Based on recently excavated sites, some adjustments to the model have to be made regarding the
loca­tion of settlement sites, the paleoenvironment and the cause of the rise in the ground water level. In this article, it is argued that
not only the creek ridges but also the former mud flats were used for settlement sites. The environment should be characterised as a
patchwork of lakes, alder cars, willow shrubs, marshy grasslands, dry nutrient-rich arable fields and riparian forests, instead of as an
open, almost treeless freshwater environment. During the Late Bronze Age, marine influxes occurred resulting in brackish environments in the vicinity of the settlement sites. It is argued that the rise of the local ground water level was due to fluctuations in the flood
basin effect caused by changes in the morphology of tidal inlets and tidal basins. An earlier opening of the Vliestroom in the Middle
Iron Age or the end of the Early Iron Age is proposed based on the apparent marine influxes and the change in the settlement pattern.
Die Paläo-Umwelt des östlichen Westfriesland: Ein kritischer Rückblick
Paläogeografie, Westfriesland, Bronzezeit, Umwelt
In den 70er und 80er Jahren des letzten Jahrhunderts wurden zahlreiche Ausgrabungen in Westfriesland durchgeführt. Anhand
der Forschungsergebnisse hat man ein Siedlungsmodell für die Bronzezeit entwickelt. Aufgrund neuer Ausgrabungen ergeben sich
Anpassungen des Modells, in Bezug auf die Wahl der Siedlungsstandorte, die Paläoökologie und die Ursache für den beobachteten
Anstieg des Grundwasserspiegels. In diesem Artikel wird behauptet, dass nicht nur die höher gelegenen ehemaligen Priele, sondern
auch die ehemaligen Seemarsche besiedelt wurden. Die natürliche Umgebung in diesem Zeitraum kann als ein Mosaik aus Seen,
Erlenwäldern, Weidengebüschen, Feuchtgrünland, Äckern und Auwäldern mit Eiche und Esche bezeichnet werden, statt einer
offenen, fast baumlosen Landschaft mit Süßwasserseen und Sümpfen. Während der Späten Bronzezeit ist ein mariner Zustrom
aufgetreten, wodurch Brackwasser-Biotope in der Nähe der Siedlungen entstanden. Die Höhe des Grundwasserspiegels ist abhängig
von den Schwankungen im Hochwasseraufnahmegebiet. Auf der Grundlage des deutlich marinen Einflusses und der Änderung
der Siedlungsstruktur in der Mittleren Eisenzeit, lässt sich die Entstehung des Vliestroomes an den Anfang der Mittleren Eisenzeit
datieren.
Studien zur nordeuropäischen Bronzezeit, Band 1, 161–169
161
W. K. van Zijverden
Introduction
In the second part of the twentieth century, large-scale re-allotments were carried out in West-Frisia (fig. 1). Soil surveys
were conducted prior to these re-allotments. In the eastern
part of West-Frisia, an abundance of archaeological remains
dating from the Middle and Late Bronze Age were found in
the subsoil. Rescue excavations were carried out by the University of Amsterdam and the State Service combined with
systematic field surveys and a survey through aeri­al photography (see Roessingh in this volume). Apart from the
bone assemblage of the excavation Bovenkarspel Het Valkje,
an assessment of the botanical remains and a selection of the
survey by aerial photography of the re-allotments “Westwoud” and “De Streek”, nothing has yet been published
(IJzereef 1981. Buurman 1996. De Vries-Metz 1993).
Based on the assembled data, a model was published in 1983
for the rise and fall of Bronze Age civilisation in West-Frisia
in relation to the development of the landscape (Van Geel
et al. 1982/1983). This model plays a major role in planning
archaeological research. Since 2000, several large-scale excavations have been carried out indicating that the model is
incorrect to some extent (Lohof/Vaars 2005. Schurmans 2010. Roessingh/Lohof 2011). In this article,
the palaeogeography of West-Frisia will be described, including the new coastal development model. The habitation
model, which has been used over the last 35 years, is briefly
described. New data derived from the excavations of Hoogwoud, Medemblik-Schepenwijk and Enkhuizen-Kadij­ken
is presented (fig. 1). Based on the new data, the habitation
model is critically reviewed and placed in a regional palaeogeographic context.
Fig. 1. Study area, sites and re-allotments mentioned in the article
A: West-Frisia, B: Westwoud, C: De Streek, D: sites 1 Opperdoes 2 Medemblik-Schepenwijk 3 EnkhuizenKadijken 4 Bovenkarspel Het Valkje, 5 Hoogwoud, E: other excavated Bronze Age sites.
162
The palaeoenvironment of eastern West-Frisia: a critical review.
Palaeogeography
The palaeogeography of West-Frisia is relatively well stu­died
due to extensive soil mapping for agricultural purposes. After
World War II, the government decided that the food production in The Netherlands had to be self-sufficient. Therefore,
large-scale re-allotments were planned and carried out. Prior
to these re-allotments, a large-scale soil mapping programme
was carried out. Based on the data derived from the soil mapping programme, a first reconstruction for the genesis of the
landscape of North Holland was published (Pons/Wiggers
1959; 1960). A slightly revised pa­laeographic model was published in the early eighties, provi­ding an overwhelming number of radiocarbon dates (De Mulder/Bosch 1983). In this
reconstruction, the transgression-regression theory was used
as an explanation for changes in sedimentation and erosion
within the tidal basin. According to this theory, slight differences in the pace of the relative rise of sea levels cause changes in sedimentation and erosion. At the end of the twentieth
century, a new theory for the development of tidal basins was
published (Van der Spek 1994). According to this theory,
the morphology of the tidal inlet and the morphology of the
tidal basin in combination with the relative rise in sea levels
are the main factors controlling the sedimentation or erosion
rates. Van der Spek applied this theory to reconstruct the development of the Bergen basin (Van der Spek 1994, 152–
180). In 2011, a new series of palaeogeographic maps for The
Netherlands was published (fig. 2).
Fig. 2. Palaeogeography of the study area according to Vos et al. (ed.) 2011
a: West-Frisia, b: sites mentioned in article, c: beach barrier and dunes, d: beaches, e: tidal basin, f: peat, g: brackish and salt water, h: freshwater, i: rivers, A: Bergen inlet, B: Oer-IJ estuary, C: Flevo Lagoon, D: Vliestroom,
1: river Vecht, 2: river IJssel.
163
W. K. van Zijverden
The Bergen basin is situated at the location of the Pleistocene river valley of the river Rhine. In this area, the ri­
vers Vecht and Eem debouched at the start of the Holocene. Due to a rapidly rising sea level, the Pleistocene river
valley “drowned” and a large-scale tidal basin was formed.
Between 7000 and 5500 BP, the rate of the relative rise in
sea level diminished, leading to a closure of the Dutch coast
with beach barriers and coastal dunes. The tidal basin can
be compared with the modern Wadden Sea for this period. Between 5500 BP and 3700 BP, the tidal basin can be
described as an area dominated by large tidal creeks with
high levees accompanied by marine crevasse splays and vast
open basin areas (fig. 3a). In this landscape, man’s presence
is prominent. Excavated sites dating from this period are the
subject of investigation in the project “Unlocking North
Holland’s Late Neolithic Treasure Chest”.1 Around 3700
BP, the Bergen basin diminished due to a disconnection
with the drainage basin area of the river Vecht. Within the
Bergen basin, this led to a rise of the mean high water level
and an increase in the sedimentation rate. In this period, the
landscape changed into a mudflat area comparable to the
present day mudflat area “Verdronken land van Saeftinghe”
(Fig. 3b). Around 3300 BP, the Bergen inlet closed causing a drop in the groundwater level within the tidal basin.
The eastern part of West-Frisia can be described as a former
mudflat area which is characterised as a freshwater environment with a patchwork of lakes, marshy areas and arable
soils with a high natural fertility.
Around 50 AD, the drainage pattern in the hinterland
changed dramatically. The Vliestroom originated in this period, draining the lakes in the central part of The Netherlands and connecting the freshwater lakes with the marine
environment of the Wadden Sea.
The habitation model
The model for Bronze Age habitation of West-Frisia is interlinked with the palaeogeographic model. After the closure
of the Bergen inlet, the creek ridges were colonised by far­
mers. The first house plans in eastern West-Frisia date from
between 1400 and 1500 BC. There is almost no evidence for
human presence in the area prior to this date. Different dates
are mentioned for the end of the habitation period. The
latest houses in the Bronze Age settlement areas date from
between 850 and 750 BC. In West-Frisia, settlement sites
dating from the Early Iron Age (750–500 BC) are absent.
Settlement sites dating from the Middle Iron Age and Late
Iron Age are rare but not unknown, and are, with a few exceptions, situated at different locations from the Late Bronze
Age sites (Woltering 1985, 225. Van Wijk 2008).
Based on multi-proxy evidence from the excavations from
the seventies, it has been argued that at the beginning of
the exploitation of the landscape, the vegetation could be
1www.singlegrave.nl
164
characterised as an open, almost treeless area. Based on algae derived from ditches, the landscape can be characterised
as a pure freshwater environment throughout the Middle
and Late Bronze Age (Woltering 1985, 225. Van Wijk
2008). The fish bone assemblages of the old excavations also
indicate a freshwater environment, excluding the possibi­
lity of brackish water in the vicinity (IJzereef 1981, 126).
During the Bronze Age, the plants cultivated changed from
wheat to barley, suggesting wetter environments. Also at the
end of the Bronze Age, the number of weeds that preferred
more humid conditions was substantially higher. Moreover,
molluscs, mostly snails derived from ditches, indicate a more
humid environment at the end of the Bronze Age compared
to the start of the Bronze Age (Buurman 1997, 151). In
addition, it has been suggested that the attested change from
meat to dairy production is an indication of wetter conditions (Buurman 1996, 192). A final indication of wetter
conditions is the exploitation of smaller habitats by small
mammals, such as mice, in the later period (Buurman
1996, 148–149).
In the nineties, the theory of solar forcing as the explanation for the sudden disappearance of man in West-Frisia
was introduced (Van Geel et al. 1996). Based on a peat
remnant under the Westfriese Omringdijk and the Engbert­
dijksveen in the eastern part of The Netherlands, a change
was attested from Sphagnum species which favour dry summers to species favouring cooler, wetter and cloudier conditions. This change in Sphagnum species coincides with
a change in the delta 14C-value, indicating a period with a
substantially smaller number of solar flares. A direct link was
suggested between the abandonment of West-Frisia around
750 BC and the change in solar radiation. It is suggested
that this change led to a faster pace of peat formation. At the
end of the Bronze Age (around 800 BC), West-Frisia should
have been covered entirely by raised peat bogs. Due to land
clearances and selnering in medieval times, the peat has disappeared almost completely. Only under mounds, dikes,
churches and castles can remnants of this extensive peat cover be found (Borger 1975, 221).
New data
In the first decade of this century, three large-scale excavations were carried out: Hoogwoud, Medemblik-Sche­
penwijk and Enkhuizen-Kadijken (Fig. 1). Each of these
sites contributed data which do not fit easily into the model
described above.
Hoogwoud
The site of Hoogwoud is, according to the excavation report,
situated on a creek ridge. The settlement site dates from the
Middle and Late Bronze Age (1300–1000 BC). This is the
only Bronze Age site which is situated in the western part of
West-Frisia. The molluscs in the features represent freshwater or terrestrial environments. The molluscs derived from
the sediment indicate a marine fauna. The large faunal re-
The palaeoenvironment of eastern West-Frisia: a critical review.
a
Fig. 3. a: Tidal basin characterised by tidal creeks. Photo: Peter Scholle, Image courtesy Earth Science World Image Bank.
b: Tidal basin characterised by mud flats. Photo: Willy Metz.
b
165
W. K. van Zijverden
mains, like all other sites in West-Frisia, consist of domestic
animals with the exception of elk or deer (Cervus elaphus
or Alces alces). The small faunal remains consist of three
different species of duck (Anas platyrhynchos, Anas crecca
or querquedula and Anas penelope) and five species of mice,
indicating habitats from very wet and open environments to
dry and shady environments. The fish remnants of this site
comprise specimens indicating full marine environments
(Atlantic cod and sting ray), brackish environments (European flounder and thinlip mullet) and freshwater specimens
(cyprinids and Northern pike). Approximately 75 % of the
fish remnants represent a brackish environment.
The conditions for uncharred plant remains were poor.
The charred remains comprise barley (Hordeum vulgare) and
emmer wheat (Triticum dicoccum). Weeds from dry to very
wet environments are present.
The different species indicate a freshwater environment
ranging from nutrient-rich dry arable soil to very wet pastures in the direct vicinity of the settlement sites. Mainly
brackish environments, but also freshwater and marine environments, were present within reach of the settlement sites,
and were exploited accordingly. No additional information
on the palaeoenvironment was gained from bones of game.
Medemblik-Schepenwijk
The site of Medemblik-Schepenwijk is situated on a small
110 meter-wide creek ridge. The settlement site dates from
the Middle and Late Bronze Age (1450–800 BC). Features
and pottery dating from between 1100 and 900 BC seem
to be absent. Apart from domestic animals, large faunal remains of goose, elk, deer, wild boar, fox and beaver are present from the Middle Bronze Age. From the Late Bronze age,
duck (Anas crecca or querquedula), swan, crow, wild cat and
otter are also present. A very special specimen present from
the Late Bronze Age is the eagle owl. In the Middle Bronze
Age, the fish remains indicate a full freshwater environment
with mostly northern pike, cyprinids and several other species. From the Late Bronze Age, a few remains of European
flounder and mullet are present, indicating brackish environments or at least a connection with a marine environment.
Palynological research has been carried out on samples from
water wells, ditches, ard marks and a coprolite. The pollen
samples all indicate an open, almost treeless landscape, which
is no surprise considering the locations that were sampled.
In the samples from the ard marks, alder makes up to 25 %
of the sample. The coprolites from dogs lack any indicators
for brackish environments and water plants. Pollen and macro-remains from arable fields and freshwater swamps were
present in the coprolites, as well as a relatively high percentage (7 %) of willow, which is a poor pollinator. The macrobotanical remains dating from the Middle Bronze Age represent
different habitats ranging from dry nutritious arable land to
marshy grasslands. Remnants of common saltmarsh grass
(Puccinellia) and glasswort (Salicornia) indicate the presence
of a brackish or marine environment. Poorly preserved wood
from oak, alder and willow was only present in features dat-
166
ing from the Late Bronze Age. The macrobotanical remains
dating from the Late Bronze Age comprise a few indicators
for brackish environments and indicators for shrubs (or possibly woods), such as seeds of bramble and elder.
The different species of animals and plants indicate for
both periods a freshwater environment ranging from nutrient-rich dry arable soil to very wet pastures in the direct vicinity of the settlement site. For both periods, indications of
lakes are lacking. Brackish environments were present within
reach of the settlement sites. These indications are stronger
for the Late Bronze Age than for the Middle Bronze Age.
For both periods, there are distinct indications for the pre­
sence of shrubs and woodland. There was probably a wider
range of environments within reach of the settlement in the
Late Bronze Age than in the Middle Bronze Age.
Enkhuizen-Kadijken
The site of Enkhuizen-Kadijken (see Roessingh in this volume) is situated on a former mud flat. The settlement dates
from the Middle and Late Bronze Age (1600–800 BC).
The research regarding the environment did not result in
a distinct change of the environment over time. The faunal remains consist of wild boar, brown bear, elk, deer and
beaver. The small faunal remains consist of ducks, geese
and water rail, indicating open water. The remains of the
northern goshawk and the woodcock are interesting, both
being indicative of woodland and shrubs. The fish remains
are similar to the remains from Medemblik-Schepenwijk:
mainly “freshwater” fish, a few mullets and large numbers of
eel. Remnants of six different species of mice indicate a wide
variety of biotopes ranging from shrubs and marshy grasslands to dry and arable land. The remnants of the grass
snake are an indication of the presence of open water. Palynological research has been carried out on a soil horizon
and a ditch. The pollen analysis indicates an open, almost
treeless landscape with (marshy) grassland, which again
is no surprise considering the location of the samples. The
presence of spores indicative of cow dung is to be expected.
The macrobotanical analysis produced distinct indications
for seepage in the Middle Bronze Age. There are only few
indications for seepage in the Late Bronze Age, indicating
a rise in the groundwater table over time. A change in cultivation from wheat to barley could not be confirmed, while
both species were present in Middle and Late Bronze Age
contexts. Wooden objects made of oak, alder, ash, birch, willow and pine (one object) were found. In a few samples, an
indication of brackish environments was present, for example the seeds of pickle weed. A blueberry (Vaccinium species)
indicates the presence of acidic soils.
At some locations within the site Enkhuizen-Kadijken,
the original soil profile was intact. At two locations, a sample was taken for a micromorphological analysis. The main
goal of this analysis was to answer the questions concerning
the genesis of a pitch black A-horizon and the peat growth
after the abandonment of the site. The black colour of the
A-horizon was caused by repeatedly burning the surface. The
The palaeoenvironment of eastern West-Frisia: a critical review.
charcoal in the soil horizon comprised mainly epidermis of
grasses and sedges, but also vascular tissue of trees. After the
abandonment of the settlement site, renewed sedimentation
took place. At first, the regular burning of the surface was
continued. Distinct layers of charcoal particles alternate
with very small silt particles. After a while, the sedimentation took place in a back swamp environment, uninterrupted by burning activities. No peat growth occurred.
The different species indicate a freshwater environment in
the vicinity of the settlement area throughout the Middle
and Late Bronze Age. The game, the small mammals and
the birds are particularly indicative of the presence of woodland and shrubs, but also dry arable land, marshy grasslands
and open water. The wide range of tree species, represented by the wooden objects, also indicates different types of
woodland within reach of the settlement site. The fish and
macro­botanical remains indicate the exploitation of brackish environments within reach of the settlement site. The micromorphological analysis was especially valuable, providing
proof of the absence of peat after the abandonment of the
settlement site and indication of renewed sedimentation in a
back swamp environment.
For all the sites, the supposed change from meat to dairy
production could be neither validated nor invalidated. A
small increase in sheep remains from the Late Bronze Age
compared to the Middle Bronze Age was established for
Medemblik-Schepenwijk and Enkhuizen-Kadijken, but was
lacking for the site of Hoogwoud. An increase in sheep remains is used by IJzereef as a complementary argument for a
change from meat to dairy production and a wetter environment (IJzereef 1981).
Discussion
The natural landscape of the eastern part of West-Frisia
has been described in the habitation model as a very open
freshwater environment. The new data, however, present indications of a much more differentiated landscape than previously thought. A patchwork of lakes, marshy grasslands,
dry arable fields alternating with patches of woodland and
shrubs must have been present. Based on the wood species
found in the excavations, willow shrubs were present as well
as alder carrs. Apart from these types of shrubs and woodlands, riparian forests with ash and oak must have been present as well. The game assemblage with wild boar, brown bear,
northern goshawk and woodcock is consistent with the presence of these specific woodland biotopes.
The fish assemblage differs in composition for almost
every site: Hoogwoud represents a brackish environment,
Medemblik-Schepenwijk represents a freshwater environment with a distinct brackish influence, or at least a direct
connection to marine environments. Enkhuizen-Kadijken
represents an almost entirely freshwater environment, while
the nearby site Bovenkarspel Het Valkje represents an en-
tirely freshwater environment. The macrobotanical remains
are in accordance with this picture. Of particular interest are
the indications for a slight change into a more brackish environment at Medemblik-Schepenwijk based on fish remains
as well as macrobotanical remains. The question is how one
should interpret these indications of brackish environments.
One problem is that there are no good pollinators within
brackish and marine environments which give a clear signal
in the pollen sample locations used in the archaeological research, such as peat bogs, ditches, ard marks and water wells.
Only the coprolites could give an indication depending on
the environments exploited by the animal during a day. It is
a pity that only three of these have been analysed for pollen
and are therefore of no use in this discussion. The differences
may be interpreted as representing different environments in
the vicinity of the settlement sites during the habitation. It
implies at least the occurrence of marine influxes in various
parts of West-Frisia during Bronze Age habitation.
The habitation model assumes a rise of the groundwater
table. A macrobotanical analysis of Enkhuizen-Kadijken in
particular demonstrates a diminishing number of indicators
for seepage from the Middle Bronze Age to the Late Bronze
Age, indicating a rise of the groundwater level du­ring this period. Indications of wetter conditions as stated in the model, a change from meat to dairy production, a change from
wheat to barley and an increase of weeds indicating wetter
conditions could be neither validated nor invalidated.
The habitation model assumes that the creek ridges were
the only place suitable for settlement sites. The excavation of
Enkhuizen-Kadijken clearly proves that settlement sites also
occur on mudflat deposits. It also proves that this mudflat was
in use as a settlement site until 800 BC. The model assumes
extensive peat growth due to higher precipitation leading to
abandonment of the settlement sites. The micromorphological analysis proved the absence of peat growth and a gradual
change to sedimentation in a back swamp environment.
Brackish environments in the eastern part of West-Frisia
can be easily explained if a connection with the Oer-IJ estuary was present from the start of the Middle Bronze Age. Actually, there is no indication that such a connection did not
exist. A change to more brackish circumstances towards the
Late Bronze Age can be explained with an earlier connection
to the Wadden Sea (Vliestroom) or the occurrence of events
such as storm surges. The marine-brackish environment for
the site of Hoogwoud is difficult to explain. The closure of
the Bergen inlet was possibly not as complete as expected.
Marine sediments dating after 3300 BP are unknown in the
western part of West-Frisia, however, the available dates for
the sediments are mainly based on radiocarbon dates from
molluscs.
A rise in the groundwater level is easily explained as being
due to the rise of the relative sea level. However, this does not
explain the renewed habitation in the Middle and Late Iron
Age, for instance at sites such as Opperdoes (Woltering
167
W. K. van Zijverden
1985, 225. Van Wijk 2008), and therefore additional explanations are needed. Changes in the drainage basin effect in the
Flevo Lagoon can cause rapid rises and falls of the surface water
level leading to changes in the groundwater level. For example,
the surface water level in the Flevo Lagoon was approxi­mately
15–60 cm below mean high water around 3700 BP due to
the drainage basin effect. Around 3300 BP, the surface water
level was approximately equal to mean high water (Van de
Plassche et al. 2005). Sedimentation in a back swamp environment and the lack of peat growth fits very well into the idea
of temporarily higher water levels in the Flevo Lagoon.
Another factor leading to a rise in groundwater level is differential local subsidence due to oxidation of organic matter,
compaction and auto loading. An extensive ditch system was
maintained in the Middle Bronze Age. Based on the mollusc analysis, these ditches were dry during a large part of the
year. The ditches probably also had an important function
for an enlargement of surface runoff. The large number of
water pits at the site Enkhuizen-Kadijken in the ditch systems supports this idea. Digging ditches leads to drainage
of the soil and therefore to subsidence, hence the rise of
the relative groundwater level. The sedimentation in a back
swamp environment at Enkhuizen-Kadijken leading to the
abandonment proves that there was a significant rise in the
surface water level. Moreover, the lack of a proper date of
this phase does not help to move the discussion forward.
The closing of the Bergen inlet resulted in erosion in the
Oer-IJ estuary due to an enlargement of the tidal basin
(Kok 2008, 85). Between 550 and 400 BC, the Oer-IJ estuary sil­ted up, probably due to the appearance of an opening towards the Wadden Sea (Kok 2008, 91). A date for the
connection to the Wadden Sea at the start of the Middle
Iron Age fits very well with the renewed habitation in eas­
tern West-Frisia. It also explains the oxidation of a vast peat
area in the lower reach of the river IJssel and the occurrence
of sites dating from the Middle Iron Age at locations in the
cover sand area which had already been abandoned at the
end of the Middle Bronze Age (Kok 2008, 91). AMS dates
derived from a marine gully in the Flevo Lagoon indicating
marine activity in the Flevo Lagoon at the end of the Early
Iron Age are also in accordance with an earlier connection to
the Wadden Sea (De Moor et al. 2009).
Conclusions
After 35 years, the habitation model for West-Frisia needs
to be revised. Recent excavations have proven the presence
of settlement sites at a mudflat which was thought to be uninhabitable. The natural environment showed more variety
than expected. At least at the site of Enkhuizen-Kadijken,
peat growth did not cause the abandonment of the settlement. Sedimentation in a back swamp environment was the
actual cause. A rise in the groundwater level has been confirmed by recent excavations. This rise was probab­ly triggered
by regional changes in the morphology of the tidal inlets and
168
tidal basins influencing the flood basin effect. In addition,
differential subsidence due to the maintenance of extensive
ditch systems from the Middle Bronze Age onwards led to
a higher relative groundwater level. An enlargement of the
precipitation due to a decrease in solar activity is still likely
to have contributed to the abandonment. However, it is definitely not the cause of a wetter environment, but could have
been the last straw. Brackish environments can be explained
by marine influxes due to storm surges. An earlier opening of
the Vliestroom around 550 BC rather than 50 AD fits very
well into the regional site distribution and is supported by
the observation of marine sediments dating from the latter
part of the Early Iron Age in the Flevo Lagoon.
Literature
Borger, G. J. 1975: De Veenhoop. Een historisch-geografisch onderzoek naar het verdwijnen van het veendek in een deel van
West-Friesland. Dissertation, University of Amsterdam.
Buurman, J. 1988: Economy and environment in Bronze Age
West-Friesland, Noord Holland (from wetland to wetland). In:
P. Murphy/C. A. I. French (ed.), The exploitation of wetlands
British Archaeological Reports 186. Oxford 1988, 267–292.
Buurman, J. 1996: The eastern part of West-Friesland in later prehistory. Dissertation, Leiden University.
Buurman, J. 1997: Archaeobotanical investigations of a Middle
and Late Bronze Age settlement site at Westwoud (West-Friesland). Berichten Rijksdienst voor het Oudheidkundig Bodemonderzoek 43, 1997, 99–140.
Geel, B. van/Hallewas, D. P./Pals, J. P. 1982/1983: A Late
Holocene deposit under the Westfriese Zeedijk near Enkhuizen
(Prov. Of Noord-Holland, The Netherlands): paleoecological
and archaeological aspects. Review of Palaeobotany and Palynology 38, 1982/1983, 269–335.
Geel, B. van/Buurman, J./Waterbolk, H. T. 1996: Archaeological and palaeoecological indications of an abrupt climate
change in The Netherlands, and evidence for climatological tele­connections around 2650 BP. Journal of Quaternary
Science 11, 1996, 451–460.
IJzereef, G. F. 1981: Bronze age animal bones from Bovenkarspel,
the excavation at Het Valkje. Dissertation, University of Amsterdam.
Kok, M. S. M. 2008: The homecoming of religious practice: an
analysis of offering sites in the wet low-lying parts of the landscape in the Oer-IJ area (2500 BC–AD 450). Dissertation,
University of Amsterdam.
Lohof, E./Vaars, J. 2005: Een nederzetting uit de Bronstijd te
Hoogwoud, gemeente Opmeer. ADC-rapport 401, Amersfoort 2005.
The palaeoenvironment of eastern West-Frisia: a critical review.
Moor, J. J. W. de/Bos, J. A. A./Bouman, M. T. I. J./Moolhuizen, C./Exaltus, R./Maartense, F. P. A./Linden, T. J. M.
van der 2009: Definitief archeologisch onderzoek in het tracé
van de Hanzelijn in het Nieuwe Land, een interdisciplinair
geo-archeologische waardering van een begraven landschap van
Oostelijk Flevoland. Delft 2009.
Mulder, E. F. J. de/Bosch, J. H. A. 1982: Holocene stratigraphy,
radiocarbon datings and paleogography of central and northern
North-Holland (The Netherlands). Mededelingen Rijks Geo­
logische Dienst 36-3, 1982, 111–160.
Plassche, O. van de/Bohncke, S. J. P./Makaske, B./Plicht,
J. van der 2005: Water-level changes in the Flevo area, central
Netherlands (5300–1500 BC): implications for relative mean
sea-level rise in the Western Netherlands. Quaternary International 133–134, 2005, 77–93.
Pons, L. J./Wiggers, A. J. 1959: De Holocene wordingsgeschiedenis van Noord-Holland en het Zuiderzeegebied. Deel I, Tijd­
schrift Koninklijk Nederlands Aardrijkskundig Genootschap
76, 1959, 104–152.
Pons, L. J./Wiggers, A. J. 1960: De Holocene wordingsgeschiedenis van Noord-Holland en het Zuiderzeegebied.
Deel II, Tijd­schrift Koninklijk Nederlands Aardrijkskundig
Genootschap 77, 1960, 3–57.
Roessingh, W./Lohof, E. 2011: Bronstijdboeren op de kwelders. Archeologisch onderzoek in Enkhuizen-Kadijken. ADCrapport 2200, Amersfoort 2011.
Schurmans, M. D. R. 2010: Een nederzetting uit de Midden en
Late Bronstijd te Medemblik-Schepenwijk II, gemeente Med­
emblik. Zuidnederlandse Archeologische Rapporten 40, Amsterdam 2010.
Spek, A. F. J. van der 1994: Large scale evolution of Holocene
tidal basins in the Netherlands. Dissertation, Utrecht University.
Vos, P. C./Bazelmans, J./Weerts H. J. T./Meulen, M. J. van
der (eds.) 2011: Atlas van Nederland in het Holoceen, landschap en bewoning vanaf de laatste ijstijd tot nu. Amsterdam
2011.
Vries-Metz, W. H. de 1993: Luchtfoto-archeologie in Oostelijk
West-Friesland. Dissertation, University of Amsterdam.
Wijk, I. van 2008: Definitief archeologisch onderzoek (DAO)
van de leidingsleuven en het wegtracé te Opperdoes-KluitenZuid, ArchOL rapport 97, Leiden 2008.
Woltering, P. 1985: Prehistorie en Romeinse Tijd in West-Friesland. West-Frieslands Oud & Nieuw 52, 1985, 199–232.
Addresses of the author
Wilko K. van Zijverden
Leiden University
Faculty of Archaeology
PhD student
Postbus 9515
NL-2300 RA Leiden
[email protected]
Saxion University of Applied Sciences
HBO-Archeologie
Lecturer Archaeology
Postbus 501
NL-7400 AM Deventer
[email protected]
169
170