Dark earth

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This article is about the archaeological horizon. For the computer game by the same name, see Dark Earth (video game). For the soil in South America, see Terra preta

Dark Earth in archaeology is an archaeological horizon often as much as 2 - 3 ft (0.6m - 0.9m) thick which covers Roman remains, notably in London and in Roman ruins in the rest of England, particularly urban ones. The stratum underlying the dark earth is often of a date varying from the 2nd to the 5th Century AD, and the stratum overlying is often, in the City of London, 9th Century. The Dark Earth shows little evidence of any depositional structure in it or even of horizons, although tip lines are sometimes seen.

The material is high in organic matter, including charcoal which gives it the characteristic dark colour; it also contains fragments of brick and tile. It may represent vacant lots on the edge of urban centres and in London has been taken as evidence of the decline of Londinium's population or of its partial displacement outside the city walls. A minority of archaeologists see it as reworked urban stratigraphy, maybe timber, smoke-impregnated thatch, decayed weeds and earth floors reworked by worm action.^[1] They argue that late Roman cemeteries around London do not show a population decline compared with earlier London. More recent reworked stratigraphy ideas are based around theories that abandoned soils were reworked by agricultural action such as ploughing which mixed building materials from the abandoned Roman cities into stratigraphy higher up the sequence.

Dark Earth was originally called 'Black Earth' by archaeologists in London but because of confusion with the Black Earth soils in Russia, it was renamed Dark Earth.

A bibliography on the subject was compiled by Pete Clark and circulated on Britarch on the 13 October 2006.^[2]