Eckmeier, Eileen

Gerlach, Renate

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Special Volume 3 (2012), pp. 11–16Renate Gerlach – Eileen EckmeierPrehistoric Land Use and Its Impact on SoilFormation since Early Neolithic. Examples fromthe Lower Rhine Areain Wiebke Bebermeier – Robert Hebenstreit – Elke Kaiser – Jan Krause (eds.), LandscapeArchaeology. Proceedings of the International Conference Held in Berlin, 6th – 8th June 2012Edited by Gerd Graßhoff and Michael Meyer,Excellence Cluster Topoi, BerlineTopoi ISSN 2192-2608http://journal.topoi.orgExcept where otherwise noted,content is licensed under a Creative CommonsAttribution 3.0 License:http://creativecommons.org/licenses/by/3.0Renate Gerlach – Eileen EckmeierPrehistoric Land Use and Its Impact on SoilFormation since Early Neolithic. Examplesfrom the Lower Rhine AreaAnthropogenic soil formation; Neolithic to modern times; Lower Rhine Region.The soils of the Central European regions that have been settled since the Early Neolithic,such as the Lower Rhine Region (NW-Germany), have been influenced by agrarian soci-eties for more than 7000 years. This long history of clearing, digging, hoeing, ploughingor fertilizing has had a deep impact on soil formation—beyond the well-known phenom-ena of soil erosion and colluviation. We will present examples for soil types which wereformed as a result of human activities, and which are more archaeological rather thannatural features: 1.) Luvic Phaeozems, which can be a product of Late Neolithic burningpractices, 2.) Podzols and hydromorphic soils, which were initialized by forest clearancesmainly during the Iron Ages, 3.) Cambisols, which are cryptic Plaggen soils built up sincethe Middle Ages and 4.) A ground surface which has been widely destroyed by concealed“micro surface mining” in the Early Modern Period.Luvic Phaeozems (Relics of Chernozemic Soils) as a Product ofNeolithic Slash and Burn TechniquesBuried humic and clay-rich dark soil remains (Bht horizons) in the Lower Rhine Basin(NW Germany) were formerly described as a typical component of Luvic Phaeozems.These Luvic Phaezomes had been considered as being evidence for the existence of Cher-nozems at the beginning of the Neolithic period in 5500 cal BC. Field observations, geo-chemical results and ages contradict this interpretation:1 the Bht horizons in the LowerRhine Basin occur in a patchy distribution independent of relief position and climaticcondition, and they are mostly connected with artefact-free but man-made pits (off-sitefeatures) consisting of the same Bht material (Bht-pits) (Fig. 1). The presence of charredorganic matter (pyrogenic carbon or Black Carbon) and its radiocarbon ages suggestthat these Bht horizons are not relics of naturally formed soils but rather archaeologicalfeatures caused by prehistoric burning practices. Pyrogenic carbon, mainly producedduring the Young to End Neolithic period (4400–2200 BC), led to the characteristicdark coloring of the soil material. During this time span, slash and burn techniques werewidely used in Central Europe.2Although the field observations and the geochemical characteristics of the Bht fea-tures reflect a strong human impact, the parent material of the formation of Bht horizonswas expected to be Pleistocene loess. New IRSL and OSL dating of the parent material(around 6.4–4.3 ka) indicate that the Bht horizons in the Lower Rhine Basin formed inearly colluvial sediments, which also date to the Young to End Neolithic period (Fig. 1).1 Gerlach et al. 2011.2 Schier 2009.12 Renate Gerlach – Eileen EckmeierFig. 1 | Excavation Düren-Arnoldsweiler: profile section with OSL samples. The dark humic and clay-richilluviation horizon (Bht) is connected to Bht pits. Both Bht features are covered by younger colluvia (M),which preserved the brighter eluviations horizon (Al). OSL ages (ka): 1639-81 (M-horizon) = 2.12 ± 0.24,1639-82 (Al-horizon) = 4.30 ±0.43, 1639-83 (Bht-horizon) = 6.23 ± 0.73, 1639-84 (Bt-horizon) = 18.9 ± 2.0,1639-86 (Bht-pit) = 5.90 ± 0.60. Gerlach et al. 2011.Thus, the history of human induced soil erosion in the Lower Rhine area started morethan 1000 years earlier than assumed, and was most likely connected to Neolithic burningpractices which subsequently triggered soil erosion, and then influenced the formation ofdark soils by eluviation and illuviation of the partly charred dark humic material, forminga Bht horizon which can be misunderstood as a diagnostic horizon of a natural LuvicPhaeozems. These Anthrosols are an example of strong human impact on soil-formingprocesses since the onset of agriculture.Pedogenesis of Podzols and Hydromorphic Soils after ForestClearancesUprooting and farming change the soil-forming processes of sandy parent material to thepoint of intensive leaching of nutrients which can at last lead to a transformation fromCambisols to hardly-usable acid Podzols. Removal of crops and grazing animals enforcethe depletion and may induce human mobility after abandoning arable fields. AlthoughPodzols can be a result of climatic conditions, the Podzolization during the Holocene inCentral Europe must be seen mainly as an anthropogenic process.3Theo Spek4 analyzed the interaction between soil properties and distribution of set-tlements in detail for the Drenthe (NL). This landscape in N-Netherlands is dominatedby glacial deposits with a wide range of sandy to clayey sediments. While the first localNeolithic occupation (around 3400 BC) started by using sandy soils, probably with Cam-bisols, adjacent Podzolization enforced the later prehistoric farmers to shift more andmore to loamy soils with better nutrient supply. Especially the plough enabled utilizationof clayey soils since the Middle Ages, while the sandy podzolized areas were covered byheathland.Also hydromorphic soils, Gleysols as well as Histosols can be a result of deforestationand anthropogenic land use. They are controlled by groundwater conditions, which canchange dramatically after opening a landscape. Especially the Iron Age period (800–50BC) is characterized by a human-induced rising of the groundwater level as a result ofextensive clearings. Archaeobotanical and geaorchaeological results show that new creeks,hydromorphic soils and swamp areas were created in the Lower Rhine Area during thisperiod.53 Goudie 2006.4 Spek 1996.5 Meurers-Balke 1999, Becker 2005.Prehistoric Land Use and Its Impact on Soil Formation 13Humic Cambisols as Cryptic Plaggen SoilsFor centuries, arable land and sandy soils have been fertilized with Plaggen, a mixture ofmanure, sods, litter and sand. While in the Netherlands, Plaggen soils are widespread,they are more or less missing in the same sandy parent material beyond the Dutch-German border. Regional soil maps only display a humic Cambisol,6 which is definedas a natural soil type.During archaeological excavations in the northern part of the lower Rhine Region, wefound that most of the so-called humic Cambisols tend to be Plaggen soils. Some distinctproperties such as the sods of typical Plaggen soils are missing and led to them being inter-preted as natural formed soils. Generally it is not easy to distinguish between an umbrichorizon and a plaggic horizon by using hand augers. Clear evidence of anthropogenicfeatures is required to differ between the two.7The discussion about the age of Plaggen soils is still ongoing because it is difficultto date the relocated soil material by incorporated archaeological finds or charcoal. Bothcould be also relocated and yield only maximum ages while the sedimentation of thePlaggen material can be significantly younger.8 Dating the last sedimentation process isonly possible using the Optical Stimulated Luminescence technique (OSL). A first reliableOSL dating of a humic sandy horizon at the Lower Rhine Region, which can be nowreinterpreted as a plaggic horizon, yields an age of 1.1 ± 0.1 ka.9 This is one of the oldestages (early High Middle Ages) of a plaggic horizon in the Dutch-German Region.Digging and Filling: Alteration of the Soil SurfaceThe technique of fertilizing by direct deposition of more or less enriched (organic oranorganic) soil material (e.g. Plaggen or marl), especially from the Early Modern Periodonwards, formed not only banked-up soils but also created excavated areas that changedthe micro-relief and perforated the ground surface.Since the 19th century, industrialization required a huge amount of building materialsuch as brickearth, sand and gravel. Most of these historic pits are more or less completelyrefilled with soil material and are nearly invisible at the surface and in the auger. However,the disturbance of the original surface as well as the filled-in soil material—often withrelocated artefacts—limits the possibility of reconstructing archaeological sites. It hasbeen shown that more than 10 percent of a rural landscape can be affected by suchsoil disturbances, and this is only the part which can be identified based on our sources(e.g. hollows in Digital Elevation Models (DEM’s)), the true amount is definitely larger(Fig. 2). This means that rural landscapes are more deeply affected by direct anthro-pogenic soil and relief modifications than was assumed before.10ConclusionFrom a pedological point of view it is necessary to consider that since the onset ofthe Neolithic period, human activities have had a much greater impact on soil formingprocesses than reflected in the major soil classification systems.6 Umbrisol after FAO 1998.7 FAO 1998.8 Spek 2006.9 Burow 2010.10 Gerlach, Herzog, and Koblinski 2008.14 Renate Gerlach – Eileen EckmeierFig. 2 | Rural landscape (2km2) in the Loess Region near Aachen (Baesweiler). Left: The digital soil map(Geological Survey of Northrhine-Westfalia) mainly recorded Luvisols (brown) Colluvia (red) and someindustrial soil destructions (NE corner). Right: The shaded relief of the DEM revealed that the landscape isstrewn with artificial hollows = historic marl and brickearth pits.From an archaeological point of view, it may become necessary to revise conventionalwisdom of a uniform, natural soil development for many Central European soils and todiscover soil material as an archaeological feature. Prehistoric soil material, which hasbeen preserved as pit fillings or buried and banked-up soils, contains valuable informationabout the use and alteration of the ground. Geochemical data from such ancient soilmaterial can therefore be used as proxies for cultural activities, e.g. to reconstruct farmingsystems such as slash and burn practices.Prehistoric Land Use and Its Impact on Soil Formation 15BibliographyBecker 2005W.-D. Becker. Das Elsbachtal. Die Landschaftsgeschichte vom Endneolithikum bis insHochmittelalter. Rheinische Ausgrabungen 56. Mainz: Philipp von Zabern, 2005.Burow 2010C. Burow. “OSL-Datierung von spätglazialen und holozänen Sedimenten im Rahmengeoarchäologischer Untersuchungen bei Weeze-Vorselaer, Niederrhein”. unpublishedBachelor-Thesis; University of Cologne, Institute of Geography. 2010.FAO 1998FAO.World Reference Base for Soil Resources. World Soil Resources Reports 84. Rome:International Society of Soil Science, 1998. URL: http://www.fao.org/docrep/W8594E/W8594E00.htm.Gerlach, Herzog, and Koblinski 2008R. Gerlach, I. Herzog, and J. Koblinski. “Visualizing DEM. The Significance of Mod-ern Landscape Modifications in the Distribution of Archaeological Finds”. In BeyondIllustration. 2D and 3D Digital Technologies as Tools for Discovery in Archaeology. Ed.by B. Frischer and A. Dakouri-Hild. British Archaeological Reports, InternationalSeries 1805. Oxford: Archaeopress, 2008, 66–71.Gerlach et al. 2011R. Gerlach et al. “Buried Dark Soil Horizons and Archaeological Features in theNeolithic Settlement Region of the Lower Rhine Area, NW Germany. Formation,Geochemistry and Chronostratigraphy”. Quaternary International (2011). DOI: 10.1016/j.quaint.2011.10.007.Goudie 2006A. Goudie. The Human Impact on the Natural Environment. Oxford: Blackwell, 2006.Meurers-Balke 1999J. Meurers-Balke. “Die Pollenanalyse als Instrument zur Datierung von Auenablage-rungen”. Archäologie im Rheinland 1998 (1999), 145–149.Schier 2009W. Schier. “Extensiver Brandfeldbau und die Ausbreitung der neolithischen Wirt-schaftsweise in Mitteleuropa und Südskandinavien am Ende des 5. Jahrtausendsv. Chr.”. Prähistorische Zeitschrift 8 (2009), 15–43.Spek 1996T. Spek. “Die bodenkundliche und landschaftliche Lage von Siedlungen, Äckern undGräberfeldern in Drenthe (nördliche Niederlande)”. Siedlungsforschung 14 (1996), 95–193.Spek 2006T. Spek. “Entstehung und Entwicklung historischer Ackerkomplexe und Plaggen-böden in den Eschlandschaften der nordöstlichen Niederlande (Provinz Drenthe).Ein Überblick über die Ergebnisse interdisziplinärer Forschung aus neuester Zeit”.Siedlungsforschung 24 (2006), 219–250.16 Renate Gerlach – Eileen EckmeierRenate Gerlach, LVR-Amt für Bodendenkmalpflege im Rheinland, Endenicher Straße133, 53115 Bonn, Germany, r.gerlach@lvr.deEileen Eckmeier, INRES-Soil Science, University of Bonn, Nußallee 13, 53115 Bonn,Germany

Prehistoric Land Use and Its Impact on Soil Formation since Early Neolithic.
Examples from the Lower Rhine Area

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Prehistoric Land Use and Its Impact on Soil Formation since Early Neolithic. Examples from the Lower Rhine Area

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