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Pollen analysis of a 5m core describes a landscape dominated by mixed deciduous woodland from 5m to 85cm. A dramatic change in landscape appearance occurs between 85cm and 65cm and from 65cm to the top of the section the landscape is dominated by sedges and grasses with virtual disappearance of woodland. The entire sequence is probably of post-Elm Decline age, although values for Elm are quite high between 500-240cm. Plantago lanceolota is present sporadically from the base of the diagram but consistently and in higher numbers from 180cm. Cereal pollen is recorded sporadically from 150cm.
Mixed deciduous tree pollen types recorded include birch, oak, pine, lime, alder and elm. These taxa, in addition to hazel, are consistently present in relatively uniform numbers from 500cm to approximately 250cm.
Values for some tree pollen record an expansion between 230cm and 85cm (alder) and 260cm to 200cm (birch). Pine values show a little peak between 290cm and 250cm. Values for elm decline above 240cm and lime disappears above 110cm.
A dramatic close to the woodland vegetation is seen above the interval 85cm-65cm; with virtual disappearance of alder, lime and elm with very low counts for birch, oak and pine. Hazel follows the same pattern.
The other main component of this diagram is that of sedges and grasses. Sedges are consistently present in relatively large numbers; grasses too are present consistently but expand from 170cm and above. Sedges, and, to a lesser extent, grasses, replace the woodland vegetation which disappears between 85cm - 65cm.
A range of shrub and herb taxa are also recorded. Among these is the consistent presence of P. lanceolota, taken as an indicator of grassland communities and associated with Rumex and occasional cereal pollen suggests possible low scale pastoral activity in woodland clearings. The taxon is present sporadically from the base of the diagram but consistently and in higher numbers from 180cm. Additional herb taxa include Taraxacum, Umbelliferae, Rumex, Mentha, Chenopodiaceae as well as a range of Caryophyllaceae and various Compositae. Cereal pollen is present, although in low numbers. It first appears at 150cm.
Freshwater indicator taxa include the aquatic flora Menyanthes, Potamageton, Equisetum and Typha. These taxa are sporadically present throughout the diagram but most consistently within the upper part of the core, from approximately 155cm. Charophyte oogonia have been recorded through the core and are especially common between 220cm and 205cm.
There is no microscopic charcoal recorded through the core.
The sediments have accumulated in the shake-hole as a result of collapse caused by dissolution of the underlying Magnesian Limestone. The accumulated 5m of sediment show a constantly wet environment supported by sedges, grasses, aquatic flora, charophytes and green algae. These taxa suggest development of a shallow pool, which was constantly infilled with sediment and pollen from nearby sources. Carophytes (stoneworts) and green algae may have lived on the surface of the pond.
Pollen from the surrounding area shows a dominant mixed woodland environment. Clearances within the woodland for agricultural use may be interpreted from the presence of open grassland taxa such as P. lanceolota and Rumex spp.
The dramatic change in vegetation seen towards the top of the diagram with the virtual disappearance of woodland suggests active woodland clearance rather than climatic-induced change. If the climate becomes much wetter (which is likely), trees with a preference for wet landscapes would continue to flourish (alder). The record from this shake-hole indicates widespread clearance of the woodland.
The precise age of the sequence contained within the shake-hole is difficult to estimate without use of radiocarbon dating. Analogy with sites in Yorkshire and in the North York Moors suggests a possible correlation with a transition from Bronze Age to Iron Age and continuing up to the post-Roman period. At Bole Ings (Dinnin and Brayshay 1994) forest clearance in surrounding landscape and increased wetness occurs during the upper Bronze Age period. During the Iron Age, drastic woodland clearance with increased flooding and arable and pastoral activity is identified.
The lowlands of northeast England first experienced major forest clearance during the Bronze Age (Bartley ey al 1976). Climatic deterioration from the early Iron Age onwards encouraged development of marshland and bogland and this may have had a detrimental impact on woodland communities. However, the pollen diagrams such as that from Fen Bogs (Atherden 1976) show a massive woodland clearance during this time (in spite of increased wetness) and this has been attributed to human activity (Simmons et al 1993). Extensive deforestation in Britain also took place during Roman times and also during the Medieval period.
The sequence of events at the Nosterfield shake-hole site will only be clarified by a suite of radiocarbon dates.