pollen zone

views updated May 08 2018

pollen zone (pollen-assemblage zone) Characteristic pollen-and-spore assemblage classically considered indicative of a particular type of climate which was assumed to be typical of a fairly extensive geographic region. Changes from one group of pollens to another characteristic assemblage are used to define pollen-zone boundaries. The standard British ( Godwin, 1940) and very similar European post-glacial (i.e. late Devensian and Flandrian) chronology recognizes eight major pollen zones, Zones I–III being the characteristic late glacial sequence: Older Dryas (I), Allerød (II), and Younger Dryas (III). More recently, based on N. American work, the importance of regional variation in the typical zone floras has been acknowledged, and a more flexible approach to pollen-zone definition applied. Pollen-assemblage zones are defined in terms of their pollen and spore profiles alone for a particular site, and initially without reference to or matching with the standard zone models with their strong climatic links. This has enabled local changes, often anthropogenic rather than climatic, to be elucidated more clearly.

pollen zone

views updated Jun 27 2018

pollen zone(pollen assemblage zone) The pollen and spore assemblage that is considered classically characteristic of a particular type of climate over a fairly extensive region and therefore indicative of it. Changes from one group of pollens to another characteristic assemblage are used to define pollen-zone boundaries. The standard British and very similar European late Devensian and Flandrian chronology recognizes eight major pollen zones. Zones I–III characterize the late-glacial sequence (i.e. Older Dryas (I), Allerød (II), and Younger Dryas (III)). More recently, based on North American work, the importance of regional variation in the typical zone floras has been acknowledged and a more flexible approach applied to the definition of pollen zones. Pollen zones are defined in terms of their pollen and spore profiles for a particular site, initially without reference to or matching with the standard zone models, which have strong climatic links. This allows local variations, often induced by human activities rather than climatic change, to be elucidated more clearly.

pollen zone

views updated May 17 2018

pollen zone (pollen assemblage zone) The characteristic pollen and spore assemblage classically considered indicative of a particular type of climate, which was assumed to be typical of a fairly extensive geographic region. Changes from one group of pollens to another characteristic assemblage are used to define pollen zone boundaries. The standard British (Godwin, 1940) and very similar European post-glacial (i.e. late Devensian and Flandrian) chronology recognizes 8 major pollen zones, zones I–III being the characteristic late glacial sequence: older Dryas (I), Allerød (II), younger Dryas (III). More recently, based on N. American work, the importance of regional variation in the typical zone floras has been acknowledged, and a more flexible approach to pollen-zone definition applied. Pollen assemblage zones are defined in terms of their pollen and spore profiles alone for a particular site, and initially without reference to or matching the standard zone models with their strong climatic links. This has enabled local changes, often man-induced rather than climatic, to be elucidated more clearly.