Where water wells up from the earth: excavations at the findspot of the Late Bronze Age Broadward hoard, Shropshire

Discussion of the environmental history

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Discussion of the environmental history

The radiocarbon-dated sedimentary sequence from Broadward Hall provides a record of environmental change from at least 14,982–14,145 cal yrs BP unmatched in the region for its long chronology. Further pollen-stratigraphical analysis of the lowermost part of the sequence (137–50cm) will provide an important contribution to our understanding of the Late Devensian and Early Holocene vegetation history of Shropshire. The preliminary results reported here for the period spanning ~12,252 to ~8960 cal yrs BP (LPAZ BH-1; ~10,302 to ~7010 cal yrs BC) are broadly consistent with other sites in western parts of the UK.57 For example, at Crose Mere, the record of declining Betula woodland recorded after 12,601–11,351 cal yrs BP (10,310 ± 210 BP; ~10,651–9401 cal yrs BC), and the maximum expansion of Corylus shrubland attained at 10,266–9310 cal yrs BP (8730 ± 200 BP; 8316–7360 cal yrs BC),58 is compatible with the results obtained from Broadward Hall. The higher than expected proportion of Tilia woodland recorded during LPAZ BH-1 is less consistent with the majority of other sites, and may be attributed to the small, localised depositional environment and close proximity of nutrient-rich, freely draining soils suitable for Tilia growth.59

The sustained decline of Tilia woodland recorded from ~5321 cal yrs BP (LPAZ BH-2; ~3371 cal yrs BC) at Broadward Hall is consistent with the national picture for the classic ‘lime decline’ from 5000–3000 cal yrs BP.60 Given that the decline occurred during a period of sustained peat formation, the cause may be equated with paludification Type I of Grant, Waller and Groves.61 It is highly likely, however, that the further decline in Tilia from ~3900 cal yrs BP (LPAZ BH-3; ~1950 cal yrs BC) was due to the impact of human activities and, in particular, clearance of woodland for cereal cultivation. This suggestion is consistent with the findings of Grant, Waller and Groves,62 who indicate that 56% of the 164 Tilia declines recorded in the UK can be attributed to human activity.63 At Crose Mere, for example, the lime decline was recorded at 4421–3720 cal yrs BP (3714 ± 129 BP; 2471–1770 cal yrs BC) during a period of sustained human activity, including cereal cultivation, which resulted in the expansion of grassland.64 At Fenemere, localised clearance of lime, oak and elm from 3566–3266 cal yrs BP (1616–1316 cal yrs BC) corresponds to an increase in herbaceous and fern taxa (eg bracken, ribwort plantain, docks and sorrels) with accompanying evidence for cereal cultivation and pastoralism.65 These data are also broadly consistent with the record from Whixall Moss where the Tilia decline has been recorded at 3822–3169 cal yrs BP (1872–1219 cal yrs BC).66

At several Shropshire sites, including Broadward Hall, this period also records a sustained increase of plant taxa indicating heathland, notably Calluna and Erica (eg Fenemere).67 This suggests an accompanying change in soil status on the freely draining substrates (eg head deposits and diamicton), which was probably associated with a reduction of woodland cover on brown earth soils. Although the cause of heathland formation during the Middle Holocene may be due to natural processes of soil degradation and climate change to wetter conditions, at many sites, palaeoecological and archaeological evidence for Bronze Age human activities clearly indicates that anthropogenic disturbance of the environment was a probable cause.68

Deposition of the spearheads at Broadward Hall therefore occurred during a sustained period of human activity that commenced prior to ~2900–2700 cal yrs BP (~950–750 cal yrs BC) and continued throughout the main period of archaeological interest. Similar evidence for woodland clearance and cereal cultivation, and an expansion of grassland, during the later Bronze Age has been recorded at several sites (eg Fenemere) and was accompanied by localised increases in bog surface wetness and changes in wetland vegetation, which is consistent with those recorded at Broadward Hall. According to Twigger and Haslam, ‘The extent of woodland clearance in north Shropshire appears to have varied between ca. 800 [~2900 cal yrs BP] and ca. 600 [~2750 cal yrs BP] BC … Averaged over a wide area of the lowlands, possibly a third of the tree cover was removed with up to three quarters of the woodland cleared in favoured localities … such as the drier, well-drained brown earth soils on the sand and gravel deposits’. 69 Whether a similar interpretation can be applied to south Shropshire remains uncertain without further pollen studies. However, the results from Broadward Hall seemingly provide a record for human activity and environmental change during the Bronze Age that is consistent with the findings from the northern part of the county.

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