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For the soil in South America see Terra preta

Dark earth in archeology 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 not exclusively organic, it has fragments of brick and tile in it. It probably represents vacant lots on the edge of urban centres and in London is evidence of the decline of Londinium's population or of its partial displacement outside the city walls. Some archaeologists used to see it as reworked urban stratigraphy, maybe timber, decayed weeds and earth floors reworked by worm action.^[1] They would argue that cemeteries around London do not show a population decline compared with earlier London. This view is at present, that of a minority. 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 strtigraphy higher up the sequence. This accounts for some vagaries of features to appear in the Dark earth such as tiplines were the original horizon a feature was cut from has in essence being truncated horizontally by the earth being tilled. Tilling the ground will in effect redeposit material almost immediately but not exactly where it came from thus possibly preserving the impression of a feature.

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]

1. ^ Darwin on earthworms
2. ^ Dark earth bibliography