5.3 Charcoal: further analysis

A.J. Clapham

5.3.1 Sampling policy

Charcoal was retrieved from flotation samples taken during 1970s excavations as described above.

5.3.2 Method of analysis

The cell structure of all the oak and non-oak identification samples was examined in three planes under a high-power microscope and identifications were carried out using reference texts (Schweingruber 1978; Brazier and Franklin 1961; Hather 2000) and reference slides housed by WHEAS.

5.3.3 Results

The environmental evidence recovered is summarised in Tables 28, 29, 30 and 31.

The charcoal was originally analysed by C.A. Keepax. The original 1970s work did not take into account any spatial or context-related analyses, presenting a straightforward list of identifications of the remains. Reassessment addressed spatial and context-related distribution, and checked, with the benefit of more sophisticated equipment, the original identifications produced by Keepax.

Due to time constraints it was only possible to select 33 of the original 181 samples for reassessment (Table 28). The samples selected represent a range of feature types and provide reasonable spatial distribution across the site. A range of samples from all three years of excavation was also selected. Of the 33 samples, two contained slate/shale, and in one sample the charcoal fragments were considered too small to be identified with any confidence.

5.3.4 Discussion

The results of the re-analysis are presented in Table 29. In the original analysis Keepax (1979) identified 16 different taxa from 181 samples. From the 33 samples re-examined in this study 15 taxa were identified and, in general, agree with those identified by Keepax. The only species not found in this study were Prunus sp. (e.g. blackthorn), Betula sp. (birch) and Fagus (beech). When the taxa are compared from the samples studied in both analyses, there is a greater dominance of willow (Salix sp.). It is possible that use of more sophisticated modern equipment has allowed a clearer identification to be made. There is some similarity between Salix, Prunus and Betula, but in this study the lack of spiral thickenings in the vessels, the presence of uniserate rays and lack of sclariform plates means that for some fragments it has been possible to rule out Prunus and Betula in favour of Salix. Alternatively, it may be that the pieces available for this study were not large enough to encounter any of these features intact. The results of the comparison of the two datasets are given in Table 30.

Quantitative analysis of the charcoal was not attempted in this study because the charcoal had already been broken up for previous identification purposes, therefore rendering fragment counts pointless. Weight of each charcoal taxon in each sample was also not recorded due to the difficulty in identifying the smaller fragments. Therefore the data are presented here in the form of a presence/absence distribution. Although this is not ideal, it may give some idea of the differences in distribution between feature types, as well as spatial and temporal differences.

From Table 29 it can be seen that oak (Quercus) is the most common taxon identified, occurring in 22 samples, the second most common taxon being hazel (Corylus) which in one context (0098.1/C67) was also represented by three fragments of hazel nutshell. The third commonest find was that of Maloideae, most likely Crataegus (Hawthorn), which was found in seven samples. Fabaceae, most likely gorse (Ulex sp.) or broom (Cytisus sp.), holly (Ilex aquifolium), and ash (Fraxinus excelsior) were found in five samples; yew (Taxus baccata), willow (Salix sp.) and field maple (Acer campestre) in three samples; elm (Ulmus sp.) and elder (Sambucus nigra) being present in two samples. Alder (Alnus glutinosa) was present in just one sample. With regard to the distribution to feature types, it appears that there is a larger number of taxa occurring in the Iron Age pits with two (0080, PG3) and (0098, PG3) producing nine taxa each (and associated with a wealth of other artefacts), and another Iron Age pit (0003) producing five taxa. The Iron Age inner ditch (1549) produced four taxa, as did another Iron Age pit (0128). All the other features produced three taxa or less. Holly only appears to occur in the pits.

If this recent data is combined with the data from Keepax (Table 30), the Iron Age pits are again the richest in terms of numbers of taxa. Pit 0080 produced ten taxa and pit 0098 produced 12 taxa. The Iron Age inner ditches also produce high numbers of taxa with cut 0305 having nine and cut 1549 having six. Spatial data

From studying Table 30 it can be seen at first glance that transect D appears to be the area of the site with the most diverse charcoal, but this may be due to the larger number of samples analysed from this area, especially from pit 0098. The only other area with a large number of taxa is the inner ditch 0305 (J4/5). This may represent dumping of material from a domestic hearth or some other firing process. Overall, it may be said that there is very little variation across the site. Woodland history

By the Iron Age, the majority of the trees that make up 'wildwood' had become established, although elm (Ulmus) had been declining since the introduction of agriculture during the Neolithic period, according to pollen evidence nationally. The presence of elm in these samples suggests that it was still present and may have been managed by a process such as pollarding, providing leaves for livestock fodder. Pollarding has the effect of reducing the number of flowers and therefore decreasing its representation in the pollen record. The effect on the tree is to increase its lifespan. The true nature of the elm decline is difficult to ascertain but Rackham (2003) suggests it is a combination of disease (Dutch Elm Disease) and human activity.

The taxa identified by Keepax (1979) and Clapham could be said to be the usual representatives of the wildwood. Of interest is the presence of yew (Taxus baccata), which is usually associated with limestone or base-rich soils although it can also be found on acid soils.

Not far from this site is Wyre Forest, a remnant of ancient forest. Wyre Forest is one of the largest ancient woodlands in England with more than 300ha of ancient semi-natural woodland. It is a remnant of a once extensive tract of ancient woodland that covered much of south Shropshire, south-west Staffordshire and north Worcestershire. The majority of its soils are markedly acidic (Natural England 2008). Here the dominant oak is sessile (Quercus petraea), other trees including locally frequent silver birch (Betula pendula), yew (Taxus baccata), holly (Ilex aquifolium) and scattered rowan (Sorbus aucuparia), wild service (Sorbus torminalis), crab apple (Malus sylvestris) and wild cherry (Prunus avium) (Natural England 2008). This list of tree taxa is remarkable in its resemblance to that recorded in association with the Blackstone Iron Age enclosure. The charcoal group Maloideae includes species such as the hawthorns (Crataegus monogyna and C. laevigata), wild pear (Pyrus pyraster), crab apple (Malus sylvestris), the whitebeams (e.g. Sorbus aria), rowan (Sorbus aucaparia), wild service tree (Sorbus torminalis), and Prunus sp. recorded by Keepax. The interesting thing is the occurrence of ash and elm in the archaeological record. The lack of elms today can be related to the recent devastation of the British elm populations by Dutch Elm disease. Ash may indicate some regeneration of secondary woodland after clearance in the Neolithic, as it appears to benefit from the decline of elm in the Neolithic (Rackham 2003). It is possible, therefore, that the charcoals from the Blackstone site represent typical woodland cover in the area, and, this being much the same as locally today, it might also point to substantial ecological stability and possible continuity over a long period.

Most of these trees can also be found forming hedgerows and it is a possibility that the charcoal assemblage represents clippings or trimmings from hedges as some of the charcoal consisted of roundwood. It is most likely that these original hedges were representative of the species growing in the local woodland and in many cases can be considered to be extensions of them. Combustion properties

The wood from each tree has different burning properties and this may have some effect on the taxa present in the assemblage from the Blackstone site (Table 31).

5.3.5 Conclusions

Overall, it can be seen that the identification of the taxa of the charcoal assemblage in the modern reassessment is generally in agreement with that of Keepax (1979). However, there does seem to be some variation in the identification of Salix and Prunus. This may be because a greater diversity of key characteristics can be identified with modern microscopes, and therefore absence of some characteristics allows the elimination of some species that are similar to Salix. However, it should be borne in mind that, as smaller pieces of charcoal were available for the current analysis, some of these characteristics were perhaps lacking as a result of the previous work.

The greatest number of taxa appears in the Iron Age pits which also, in some cases, produced the largest number of artefacts and charred cereal grains. Whether this reflects ritual deposition or discard after use is difficult to ascertain. One of the Iron Age inner ditches also produced a large number of taxa suggesting the dumping of burnt material. There appears to be no overall spatial pattern to the distribution of the tree taxa.

The taxa present in both analyses, when compared to the present-day composition of the nearby Wyre Forest, bear an uncanny degree of resemblance, suggesting that there may be a link between the composition of the woodland in the Iron Age and that of the present-day ancient forest.

If the burning properties of the woods are considered it can be seen that the majority are good fuel woods and some of them also give off a pleasant scent. Again it is difficult to deduce if there was any ritual significance in the choice of woods burnt but it is most likely that they were simply being used in domestic hearths.


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