Contamination of archaeological deposits by seeds of modern origin with particular reference to the use of flotation machines

Modern contamination would seem to be of widespread occurrence on archaeological sites in Britain. It is particularly noticeable when recovery is increased by the use of a flotation machine. Sources of contamination and methods of distinguishing modern and ancient seeds are discussed. It should often be possible largely to discount the recent component providing that a certain amount of consideration is given to the problem in relation to a particular site, although there are still some areas requiring further research.