Fossil bog soils (‘dwog horizons’) and their relation to Holocene coastal changes in the Jade Weser region, southern North Sea, Germany

Scheder, Juliane; Engel, Max; Bungenstock, Friederike; Pint, Anna; Siegmüller, Annette; Schwank, Stephan; Brückner, Helmut

doi:10.1007/s11852-017-0502-z

Cited by 5 publications

(5 citation statements)

References 32 publications

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“…Subsequent oxidation of (Fe-)sulphides and the decay of organic matter produce Fe-oxides, sulphuric and carbonic acid, both causing a rapid decalcification and acidification of the sediment [ 49 ]. Covered by younger tidal flat deposits of facies type C, it represents a fossil soil horizon called “Dwogmarsch” ([ 52 – 54 ]).…”

Section: Resultsmentioning

confidence: 99%

Lost in the North Sea—Geophysical and geoarchaeological prospection of the Rungholt medieval dyke system (North Frisia, Germany)

et al. 2022

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We performed geophysical and geoarchaeological investigations in the Wadden Sea off North Frisia (Schleswig-Holstein, Germany) to map the remains and to determine the state of preservation of the medieval settlement of Rungholt, especially its southern dyke segment, called the Niedam dyke. Based on archaeological finds and historical maps, Rungholt is assumed to be located in the wadden sea area around the island Hallig Südfall. During medieval and early modern times, extreme storm events caused major land losses, turning cultivated marshland into tidal flats. Especially the 1st Grote Mandrenke (or St. Marcellus’ flood), an extreme storm surge event in 1362 AD, is addressed as the major event that flooded and destroyed most of the Rungholt cultural landscape. Cultural traces like remains of dykes, drainage ditches, tidal gates, dwelling mounds or even plough marks were randomly surveyed and mapped in the tidal flats by several authors at the beginning of the 20th century. Due to the tidal flat dynamics with frequently shifting tidal creeks and sand bars, the distribution of cultural remains visible at the surface is rapidly changing, making it hard to create a comprehensive map of the cultural landscape by surveying. Today, the Niedam dyke area is fully covered by tidal flat sediments, depriving any remains from further archaeological investigation. Since little is known about the precise location or state of preservation of these remains, our investigation aimed at the rediscovery of the medieval dyke system and associated structure with modern and accurate geophysical, geodetical and geoarchaeological methods. Magnetic gradiometry revealed a large part of the medieval dyke, confirming two tidal gates and several terps connected inland with the dyke, providing a detailed example of a Frisian medieval dyke system. Based on our results, the so far inaccurate and incomplete maps of this part of Rungholt can now be specified and completed. Beyond that, seismic reflection profiles give a first depth resolving insight in the remains of the dyke system, revealing a severe threat to the medieval remains by erosion. The site is exemplary for the entire North Frisian coast, that was influenced by multiple flood events in the middle ages to modern times.

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Section: Resultsmentioning

confidence: 99%

Lost in the North Sea—Geophysical and geoarchaeological prospection of the Rungholt medieval dyke system (North Frisia, Germany)

et al. 2022

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“…Scott et al, 2001;Gehrels & Newman, 2004;Gehrels et al, 2002;Pedersen et al, 2009;Kemp et al, 2013), but so far, applications are lacking for the southern part of the German Bight. Besides Foraminifera, Ostracoda, small crustaceans with a bivalved calcified carapace, occur within the same sediment fractions in the wider study area (Scheder et al, 2018). We assume that Ostracoda may provide additional information for more detailed reconstructions for the lower intertidal and uppermost subtidal.…”

Section: Introductionmentioning

confidence: 89%

Vertical and lateral distribution of Foraminifera and Ostracoda in the East Frisian Wadden Sea – developing a transfer function for relative sea-level change

Scheder¹,

Frenzel²,

Bungenstock³

et al. 2019

Geol. Belg.

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In light of rising sea levels and increased storm surge hazards, detailed information on relative sea-level (RSL) histories and local controlling mechanisms is required to support future projections and to better prepare for future coastal-protection challenges. This study contributes to deciphering Holocene RSL changes at the German North Sea coast in high resolution by developing a transfer function for RSL change. Recent associations of Foraminifera and Ostracoda from low intertidal to supratidal settings of the barrier island of Spiekeroog in combination with environmental parameters (granulometry, C/N, TOC, salinity) were investigated and quantified in elevation steps of 15 cm in order to generate a first transfer function (TF) of Holocene RSL change. In a future step, the TF can be applied to the stratigraphic record. Our data show a clear vertical zonation of foraminifer and ostracod taxa between the middle salt marsh and the tidal flat with very few individuals in the sand flat area, suggesting removal by the tidal current or poor preservation. Multivariate statistics identify the elevation, i.e. the inundation frequency, as main driving factor. The smallest vertical error (49 cm) is associated with an entirely new approach of combining Foraminifera and Ostracoda for a TF. Advantages of the TF over classical RSL indicators such as basal and intercalated peat – beside the relatively narrow indicative meaning – include the possible application to a wide range of intertidal facies and that it does not depend on compaction-prone peat.

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“…C/N ratios and the lack of microfauna point to a semi-terrestrial environment in most samples. Together, these results indicate the formation of a peat, with high organic contents due to decaying vegetation and low carbonate contents resulting from decalcification processes associated with peat formation (Bungenstock 2005;Scheder et al, 2018). The locally higher TIC values (N77 and N49 C-2) may indicate an increased marine influence.…”

Section: Lithological Unitsmentioning

confidence: 86%

“…The lack of microfauna in N77 is interpreted as a very low inundation frequency resulting from the distance from the coastline which defines the upper limit of the high salt marsh. An alternative explanation is that microfauna was destroyed after the deposition of the layer or dissolved by humic acids of plant decomposition (Bungenstock, 2005;Scheder et al, 2018). The top of the salt-marsh deposits in VC13 and N44 is erosive.…”

Section: Lithological Unitsmentioning

confidence: 99%

Microfauna- and sedimentology-based facies analysis for palaeolandscape reconstruction in the back-barrier area of Norderney (NW Germany)

Elschner

Scheder

Bungenstock

et al. 2021

Netherlands Journal of Geosciences

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Palaeolandscape reconstructions at the German North Sea coast are essential for the understanding of coastal changes and dynamic landscape-forming processes. This study contributes to reconstructing Holocene coastal changes in the back-barrier area of the East Frisian island of Norderney and draws conclusions on the local palaeogeography. Five sediment cores were analysed in terms of sedimentology (grain-size distribution), geochemistry (TOC, TIC, N, C/N), microfauna (foraminifers and ostracods) and 13 radiocarbon dates. In order to identify driving environmental factors and support the facies interpretation, multivariate statistics (PCA) were carried out. Additional cores from the surrounding area (WASA Project and ‘Landesamt für Bergbau, Energie und Geologie’ (LBEG) Hannover) enabled correlation of the investigated cores over a transect of ~6 km, showing six depositional environments, which can be used for landscape reconstruction. Deposition starts with periglacial (aeolian and glaciofluvial) Pleistocene sediments, with subsequent pedogenesis followed by swamp conditions that develop into a salt marsh. The overlying tidal-flat sediments are partially cut by (fossil and recent) channel deposits. A hiatus at the base of the tidal-flat deposits that spans some 3000 years hints at their reworking caused by a combination of antrophogenic coastal protection measures and the impact of storms. Furthermore, based on the profile correlation and the age data, a widespread salt-marsh area with a minimum age of ~4000 cal BP is defined for the ‘Hohes Riff’ in the southwestern back-barrier of Norderney Island.

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Fossil bog soils (‘dwog horizons’) and their relation to Holocene coastal changes in the Jade Weser region, southern North Sea, Germany

Cited by 5 publications

References 32 publications

Lost in the North Sea—Geophysical and geoarchaeological prospection of the Rungholt medieval dyke system (North Frisia, Germany)

Lost in the North Sea—Geophysical and geoarchaeological prospection of the Rungholt medieval dyke system (North Frisia, Germany)

Vertical and lateral distribution of Foraminifera and Ostracoda in the East Frisian Wadden Sea – developing a transfer function for relative sea-level change

Microfauna- and sedimentology-based facies analysis for palaeolandscape reconstruction in the back-barrier area of Norderney (NW Germany)

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