Dark earth

In geology and archaeology, dark earth is a substratum, up to 1 meter (3.1 feet) thick, that indicates settlement over long periods of time. The material is high in organic matter, including charcoal, which gives it its characteristic dark colour; it may also contain fragments of pottery, tile, animal bone and other artefacts. It is interpreted as soil enriched with the sooty remains of thatched roofs from houses without chimneys, with other waste materials. In some areas it appears to give the soil added fertility.

London's dark earth was originally called 'black earth' by archaeologists. It was renamed 'dark earth' because of confusion with the chernozem (black earth soils in Russia), whose dark colour is traditionally (not universally)^[1]^[2]^[3]^[4] thought to come from humus, rather than soot.

^ Lehmann, J.; Kleber, M. (2015-12-03), "The contentious nature of soil organic matter", Nature, 528 (7580): 60–8, Bibcode:2015Natur.528...60L, doi:10.1038/nature16069, PMID 26595271, S2CID 205246638
^ Eckmeier, Eileen; Gerlach, Renate; Gehrt, Ernst; Schmidt, Michael W.I. (2007), "Pedogenesis of Chernozems in Central Europe — A review" (PDF), Geoderma, 139 (3–4): 288–299, Bibcode:2007Geode.139..288E, doi:10.1016/j.geoderma.2007.01.009, archived from the original (PDF) on 2016-03-08, retrieved 2016-02-28
^ Schmidt, M.W.I.; Skjemstad, J.O.; Jäger, C. (2002), "Carbon isotope geochemistry and nanomorphology of soil black carbon: Black chernozemic soils in central Europe originate from ancient biomass burning", Global Biogeochemical Cycles, 16 (4): 70–1–70–8, Bibcode:2002GBioC..16.1123S, doi:10.1029/2002GB001939, S2CID 56045817, These data challenge the common paradigm that chernozems are zonal soils with climate, parent material and bioturbation dominating soil formation, and introduce fire as a novel, important factor in the formation of these soils
^ Eckmeier, E. (2007), Detecting prehistoric fire-based farming using biogeochemical markers (Dissertation), University of Zurich, Faculty of Science., doi:10.5167/uzh-3752, It is now an open question as to whether Neolithic settlers did indeed prefer to grow crops where Chernozems occurred or if Neolithic burning formed the chernozemic soils.

[1] Lehmann, J.; Kleber, M. (2015-12-03), "The contentious nature of soil organic matter", Nature, 528 (7580): 60–8, Bibcode:2015Natur.528...60L, doi:10.1038/nature16069, PMID 26595271, S2CID 205246638

[eckm07-2] Eckmeier, Eileen; Gerlach, Renate; Gehrt, Ernst; Schmidt, Michael W.I. (2007), "Pedogenesis of Chernozems in Central Europe — A review" (PDF), Geoderma, 139 (3–4): 288–299, Bibcode:2007Geode.139..288E, doi:10.1016/j.geoderma.2007.01.009, archived from the original (PDF) on 2016-03-08, retrieved 2016-02-28

[3] Schmidt, M.W.I.; Skjemstad, J.O.; Jäger, C. (2002), "Carbon isotope geochemistry and nanomorphology of soil black carbon: Black chernozemic soils in central Europe originate from ancient biomass burning", Global Biogeochemical Cycles, 16 (4): 70–1–70–8, Bibcode:2002GBioC..16.1123S, doi:10.1029/2002GB001939, S2CID 56045817, These data challenge the common paradigm that chernozems are zonal soils with climate, parent material and bioturbation dominating soil formation, and introduce fire as a novel, important factor in the formation of these soils

[4] Eckmeier, E. (2007), Detecting prehistoric fire-based farming using biogeochemical markers (Dissertation), University of Zurich, Faculty of Science., doi:10.5167/uzh-3752, It is now an open question as to whether Neolithic settlers did indeed prefer to grow crops where Chernozems occurred or if Neolithic burning formed the chernozemic soils.

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