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How can we discover environments of the distant past? . What is a bog core sample?. A ‘bog core sample’. What does pollen look like? . Betula pendula (birch) . Quercus robur (oak) . Pinus sylvestris (pine). Fraxinus excelsior (ash). Salix alba (willow). Corylus avellana (hazel) .

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what does pollen look like
What does pollen look like?

Betula pendula (birch)

Quercus robur (oak)

Pinus sylvestris (pine)

Fraxinus excelsior (ash)

Salix alba (willow)

Corylus avellana (hazel)

climatic changes during the holocene
Climatic changes during the Holocene

During the Early Holocene (c. 11,500 BP up to 5000 BP) the climate became warmer and wetter.

  • Melting glaciers caused a rapid rise in sea level, with a rise of >30mm/yr at some sites.
  • The present sea level was typically reached at around 6,000 BP
  • Rainfall increased, and desert and tundra regions of the earth shrank.
  • Forest ecosystems spread in the warmer, moister conditions.
  • Humans moved from a meat-based diet based on hunting animals through open habitats to sedentary farming, that suited the new climate.

During the later Holocene (c. 5000 BP), temperatures in temperate latitudes began to cool again.

Data from http://www.cru.uea.ac.uk/cru/info/holocene/

abstract of a journal article
Abstract of a journal article

The sediment and pollen stratigraphy of a radiocarbon-dated sequence from a lake on the eastern margin of Breckland is described. The record extends from 12620 to 1620 B.P.

From 12620 to 9560 B.P. the vegetation was an open Betula woodland. Movement of sand by wind was one factor keeping the vegetation open. Between 9560 and 9255 B.P. a denser Betula woodland developed, to be replaced by a closed woodland dominated by Corylusavellana, with Pinussylvestris, Ulmus and Quercus. During this period, Quercus gradually replaced P. sylvestis on the local sandy soils. Corylusavellana remained the woodland dominant until about 7140 B.P., when it was replaced by Tiliacordata.

Alnusglutinosa expanded in response to raised water levels at about 6800 B.P., Fraxinus excelsior became an important component of the local woods, also replacing C. avellana. The elm decline occurred in two phases, at 6000 and 4500 B.P. Substantial forest clearance did not begin until about 2500 B.P. The spread of heath vegetation on the Breckland began at about 2250 B.P.

From ‘Devensian late-glacial and Flandrianvegetational history at Hockham Mere, Norfolk, England’, K.D. Bennett, New Phytologist, 95, 457-487 (1983)

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