image/svg+xml19 X/1/2019 InterdIscIplInarIa archaeologIca natural scIences In archaeology homepage: http://www.iansa.eu Review of Illuvial Bands Origin; What Might the Presence of Dark Brown Bands in Sandy Infllings of Archaeological Features or Cultural Layers Mean? Lenka Lisá a* , Aleš Bajer b , Klement Rejšek b , Valerie Vranová b , Lenka Vejrostová c , Andrzej Wisniewski d , Petr Krištuf e a Institute of Geology CAS, Rozvojova 269, 165 00 Prague, Czech Republic b Department of Geology and Pedology, Faculty of Forestry and Wood technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic c Faculty of Science, Charles University, Albertov 6, 128 43 Prague, Czech Republic d Institute of Archaeology, University of Wrocław, Szewska 48, 50 137 Wrocław, Poland e Department of Archaeology, University of West Bohemia, Sedláčkova 15, 30614 Pilsen, Czech Republic 1. Introduction The presence of bands within the sedimentary/pedological record has been of interest to diferent pedologists since the beginning of the twentieth century. The most common term for these laminated textural features are illuvial bands, but names such as pseudofbres, lamellas, laminae, clay-iron bands or covarvany, are also used in diferent references (see review, Prusinkiewicz et al. , 1998 and Kühn et al. , 2011), or, according to the US Soil Survey Staf (1999), a lamella. A textural feature called a lamella (plural lamellae; band) can develop as an illuvial horizon with a thickness of less than 7.5 cm and is intercalated with horizons poor in clay (Miedema, 1987; Kemp and McIntosh, 1989). Such accumulations are usually composed of fne-grained, silica- rich clay attached to a coarser fraction that is composed of the original soil. Illuvial bands difer in colour (higher chroma values, redder hues) (Van Reeuwijk and de Villiers, 1985). The transition between bands and the surrounding matrix is usually wavy and broken. Sometimes these bands compose a kind of web or network. A concave gefuric c/f-related (coarse/fne-related) distribution is the typical micromorphological pattern. Clay coatings cover and bridge the individual sand grains which is refected in a chitonic or chito-gefuric c/f-related distribution (Kühn et al. , 2011). Most commonly these bands are described in sandy soils, Volume X ● Issue 1/2019 ● Pages 19–28 *Corresponding author. E-mail: lisa@gli.cas.cz ARtICle Info Article history: Received: 27 th June 2018 Accepted: 1 st May 2019 DOI: http://dx.doi.org/ 10.24916/iansa.2019.1.2 Key words: illuvial bands clay-iron accumulations subsoil lamellaemicromorphologyNeolithicPalaeolithic AbStRACt The presence of lamellae (or bands) often promises an interesting sedimentary archive related to the occupation or abandonment history of a site. How exactly might such types of bands be interpreted, and how do their presence change the original primary features preserved within the archaeological structure? For this review, two archaeological sites are introduced, both distinct in many aspects, located in diferent climatic regions, but with the presence of bands preserved inside of the infll, as well as in the locality’s background. One site is related to the Magdalenian/Epigravettian occupation in south-western Poland, and the second related to the Neolithic occupation in central Bohemia. What connect these two localities are their permeable sandy background, presence of human occupation, and the development of the above-described textural features. Sedimentological observations supported by micromorphology and geochemistry, as well as by magnetic susceptibility, revealed that, in both localities, the presence of dark brown bands was the result of repeated illuviation due to a kind of podsolization process not necessarily related to human presence. The illuvial lamellae/bands at the Kly site probably originated during the Subboreal due to the increased humidity connected with the presence of the disturbed background of the infll in the ditch. The Sowin site displays, at the very least, two phases of origin. One of the phases is pre-dated by glacial conditions, and the second is of late glacial or Holocene origin. The origin of these features in both study sites is due to precipitated water and the movement of clay down the section, but under their diferent conditions.
image/svg+xmlIANSA 2019 ● X/1 ● 19–28 Lenka Lisá, Aleš Bajer, Klement Rejšek, Valerie Vranová, Lenka Vejrostová, Andrzej Wisniewski, Petr Krištuf: Review of Illuvial Bands Origin; What Might the Presence of Dark Brown Bands in Sandy Infllings of Archaeological Features or Cultural Layers Mean? 20 but their appearance in other soils is not excluded. Several of the best-developed examples of soils with illuvial bands described in Holocene (as well as Pleistocene) soils are the humic podzols of the European Aeolian Sand Belt (Koster, 2009). Gerasimova and Khitrov (2012) classifed similar soils located in glacifuvial sand in south western Poland. What is the process whereby the illuvial bands develop? What role does climate, natural processes, or human infuence play in the origin of these features? The origin of illuvial bands is generally not well understood and it remains controversial. It seems that some “trigger” (increased precipitation – Pelle et al. , 2013) activates the movement of clay, which then stops moving at a certain depth where there is some textural inhomogeneity (Bouabid et al. , 1992). Another possibility is that the origin is triggered by the precipitation, but these bands start to form at the limit of the capillary water reach (Van Reeuwijk and de Villiers, 1985), or on a transition to a more calcareous zone, i.e. at a point of a distinct pH change (Schaetzl, 1992). Stefanovits (1971) suggested that illuvial bands are the result of unfavourable conditions triggered by climate. On the other hand, the same author, as well as Tsigirintsev (1968) and Ugla and Ugla (1979), propose that illuvial bands are the result of the impact of forest vegetation. Their assumption is that the clay movement is activated by a change of pH that has been triggered by the acid “waste” from conifer trees. In this scenario, active maintenance of the vegetation by humans may play a role in the origin or absence of these features. Another trigger, difering from those mentioned above, is the local hydrology (see review in Ibrahim, 2011). Here the underground water is transporting a quantity of some iron compound that may transform at one point in time (and place) and thus form the illuvial bands. The primary sedimentary accumulation of iron, and later pedological transformation of these accumulations, may also play a role in the development of these bands (Schaetzl, 2001).This paper aims to review the possible formation processes that lead to the origin of illuvial bands and, in addition, how micromorphology and geochemistry methodological tools may help with interpreting these formation processes. What might the main triggers be and what exactly might the presence of illuvial bands mean for interpretation of human presence and the environment of a site? 2. Study sites2.1 Kly The Kly site is situated at the confuence of the Labe and Vltava Rivers in central Bohemia (Figure 1A). The