One of the parts into which pollen diagrams are divided on the basis of the total pollen assemblage found within them. Zone boundaries are placed at points where there is greatest evidence for change, hence the assemblage of pollen within a zone is relatively homogeneous. Pollen zones are defined by their content of pollen types and can be dated by reference to radiocarbon or other methods, thus enabling them to be established as chronozones. Pollen assemblage zones are thus intended to delimit periods during which the surrounding vegetation has been relatively stable. This may be due to climatic stability within that period, or to a lack of change in human land management. Various schemes have been introduced in the past, particularly by K. Jessen in Denmark and Sir Harry Godwin in Britain, which have attempted to construct regional pollen zones. In Britain, for example, a series of eight pollen zones was established by Godwin to cover the late Devensian (last glacial) and the Holocene (Flandrian). Lack of synchroneity even within the British Isles, however, has largely led to the abandonment of the scheme. Pollen assemblage zones are now constructed for each individual site and regional comparisons and correlations can then be made on the basis of chronology.