LATE WEICHSELIAN AND FLANDRIAN POLLEN DIAGRAMS FROM SOUTH-WEST SCOTLAND

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Summary

The history of Late Weichselian and Flandrian vegetation in south-west Scotland has been studied by examining sites ranging from near sea-level up to about 1500 ft O.D. (c. 500 m). Pollen was scarce or absent in Lower Dryas sediments, but the relatively high counts in Allerod sediments implied that an open herbaceous vegetation was established before this time. Throughout the Late Weichselian the vegetation was an herbaceous one which became more stable and denser during the Allerod, but was much reduced during Upper Dryas time. Early Flandrian vegetation remained open and the spread of birch woodland was delayed for some time. Once established the birch forests remained dominant or co-dominant for a long period and were never completely replaced by mixed-oak forest. Because of the differences in vegetation development it was difficult to correlate significant changes in the pollen curves with the standard British system of pollen zones. For this reason an attempt has been made to devise a system of zones appropriate for Scotland which bears comparison with the presently accepted scheme. Apparent breaks in sedimentation at Bigholm Burn and Culhorn Mains, only revealed by pollen analysis, are treated as local phenomena, the causes of which had no effect upon the character of the regional vegetation. Radiocarbon assay of samples from Bigholm Burn show that the ages of Allerod sediments are consistent with those from other parts of Britain, but early and mid-Flandrian dates are considerably younger than their biostratigraphical equivalents elsewhere. Until more dates are available from the region this apparent anomaly is regarded as being an effect of local factors influencing forest development and sedimentation. Although the distribution of sites about the Southern Uplands implies that glaciers were restricted to higher altitudes the present study does not add significantly to our knowledge of the extent of glaciation in this region during the Late Weichselian.

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