This article is about the archaeological horizon. For the video game, see Dark Earth. For other uses, see Black 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.
Restored blackhouse in a museum on Trotternish, Skye. There is no chimney on this house and the thatch becomes impregnated with soot. When the roof is replaced, the waste thatch can add fertility to the soil, resulting in dark earth.
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.
Charred material as agricultural improver
In the Hebrides, it was customary to remove the thatch from the "black houses" every spring, and spread it on the fields as fertilizer, improved by the soot which it retained. On Achill Island, special smoke huts were built in the fields, stone structures with sod roofs. From October to May smoky fires burned inside them, and in spring the sods were spread on the fields.[5] In the Amazon basin, there are very extensive areas of dark soil, known as terra preta, enriched by small particles of soot, and these areas are much more fertile than the natural soil.
Major areas
Roman Britain
In England, dark earth covers many areas that were built up in the Roman period, especially Londinium. In some cases, it may represent open spaces on the edge of urban centres, but can also be found in more rural settings in and around foci of settlement. In the example of London, deposits underlying the ancient city's dark earth are often dated to between the 2nd to 5th century, the middle and later Roman period. Overlying deposits are frequently dated to the 9th century when Saxon London was repopulated and began to expand. The dark earth shows little evidence of any depositional structure or 'horizons', although tip lines are sometimes recorded.
Archaeologists have debated what London's dark earth layer may indicate about human use of the city. It has been taken as evidence of refuse disposal or gardening during the Roman period on the site of previous buildings. In this case it might be evidence of a decline of Londinium's population, or of its partial displacement outside the city walls. However, late Roman cemeteries around London do not show a population decline compared with earlier London.
Alternatively, dark earth might have formed only after abandonment at the end of the Roman period. In this interpretation, dark earth would consist of urban deposits of smoke-impregnated thatch, decayed weeds, timber, and earth floors, reworked and homogenized by worm action,[6] or by agricultural activities, such as ploughing, that mixed building materials from the abandoned Roman cities with material deposited later.
Latest findings in France demonstrated that dark earth may originate from a change from stone to organic building materials; timber and straw will decay and build dark earth.[7][8] The presence of dark earth does not necessarily imply diminished human activity.
Sweden
In Sweden, dark earth covering 40 hectares (100 acres) has been found in Uppåkra, in Scania, southern Sweden, where a city-like settlement existed from about the year 1 until 1000 CE when the settlement shifted to modern day Lund. Dark earth over 7 hectares (17 acres) has been found in the Viking city of Björkö (today called Birka), in central Sweden, close to modern Stockholm. Dark earth has also been found in Köpingsvik, on the island of Öland close to the southern Sweden east coast.
West Africa
Dark earths occur around ruins in the Upper Guinean forests of Ghana, Guinea, Liberia and Sierra Leone.[9][10] For a period of at least 700 years, West African farmers have enriched the rain forest soils around their towns with compost derived from kitchen, animal, agricultural, and fire waste to produce a signature dark earth.[11] Dark earth is part of the local nomenclature, economically important, and is used judiciously by local communities.[10] The Loma and Mende peoples currently improve soil in this fashion. They well understand how this connects them to the durable legacy of fertile dark earth that encircles the ruined sites in the region.[9] Locals associate the age of their own towns with the depth of their black soil.[10][11]
Amazonian Dark Earths (ADEs) or terra preta do índio (in Portuguese, means "black soil of the Indian") are a type of very dark, fertile artificial (anthropogenic) soil occurring in the Amazon Basin. ADEs owe their characteristic black color to their weathered charcoal content.
↑ 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, S2CID56045817, 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
In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin word for "earth" or "ground".
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil.
Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order (anisotropy) within soils. These alterations lead to the development of layers, termed soil horizons, distinguished by differences in color, structure, texture, and chemistry. These features occur in patterns of soil type distribution, forming in response to differences in soil forming factors.
Black earth, black land or dark earth may refer to:
A biogeochemical cycle, or more generally a cycle of matter, is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle, the nitrogen cycle and the water cycle. In each cycle, the chemical element or molecule is transformed and cycled by living organisms and through various geological forms and reservoirs, including the atmosphere, the soil and the oceans. It can be thought of as the pathway by which a chemical substance cycles the biotic compartment and the abiotic compartments of Earth. The biotic compartment is the biosphere and the abiotic compartments are the atmosphere, lithosphere and hydrosphere.
Chernozem, also called black soil, regur soil or black cotton soil, is a black-colored soil containing a high percentage of humus and high percentages of phosphorus and ammonia compounds. Chernozem is very fertile soil and can produce high agricultural yields with its high moisture-storage capacity. Chernozems are a Reference Soil Group of the World Reference Base for Soil Resources (WRB)
Black soil may refer to:
The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere, biosphere, lithosphere and the hydrosphere. The pedosphere is the foundation of terrestrial life on Earth.
Terra preta is a type of very dark, fertile anthropogenic soil (anthrosol) found in the Amazon Basin. It is also known as "Amazonian dark earth" or "Indian black earth". In Portuguese its full name is terra preta do índio or terra preta de índio. Terra mulata is lighter or brownish in color.
Historical ecology is a research program that focuses on the interactions between humans and their environment over long-term periods of time, typically over the course of centuries. In order to carry out this work, historical ecologists synthesize long-series data collected by practitioners in diverse fields. Rather than concentrating on one specific event, historical ecology aims to study and understand this interaction across both time and space in order to gain a full understanding of its cumulative effects. Through this interplay, humans adapt to and shape the environment, continuously contributing to landscape transformation. Historical ecologists recognize that humans have had world-wide influences, impact landscape in dissimilar ways which increase or decrease species diversity, and that a holistic perspective is critical to be able to understand that system.
This is an index of articles relating to soil.
Chemically, black carbon (BC) is a component of fine particulate matter. Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuels, biofuel, and biomass, and is one of the main types of particle in both anthropogenic and naturally occurring soot. Black carbon causes human morbidity and premature mortality. Because of these human health impacts, many countries have worked to reduce their emissions, making it an easy pollutant to abate in anthropogenic sources.
Soil color is often the most visually apparent property of soil. While color itself does not influence the behavior or practical use of soils, it does indicate important information about the soil organic matter content, mineralogy, moisture, and drainage.
The Canadian System of Soil Classification is more closely related to the American system than any other, but they differ in several ways. The Canadian system is designed to cover only Canadian soils. The Canadian system dispenses with the sub-order hierarchical level. Solonetzic and Gleysolic soils are differentiated at the order level.
The phosphorus cycle is the biogeochemical cycle that involves the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based materials do not enter the gaseous phase readily. The production of phosphine gas occurs in isolated and specific conditions. Therefore, the phosphorus cycle is primarily examined studying the movement of orthophosphate (PO4)3-, the form of phosphorus that is most commonly seen in the environment, through terrestrial and aquatic ecosystems.
The Polish Soil Classification is a soil classification system used to describe, classify and organize the knowledge about soils in Poland.
The soil matrix is the solid phase of soils, and comprise the solid particles that make up soils. Soil particles can be classified by their chemical composition (mineralogy) as well as their size. The particle size distribution of a soil, its texture, determines many of the properties of that soil, in particular hydraulic conductivity and water potential, but the mineralogy of those particles can strongly modify those properties. The mineralogy of the finest soil particles, clay, is especially important.
The zinc cycle is a biogeochemical cycle that transports zinc through the lithosphere, hydrosphere, and biosphere.
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