A Consideration of Somerset's Holocene Environments
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10 A consideration of Somerset's Holocene environments Vanessa Straker Introduction which preserves in dry sediments a range of plants that would not necessarily have become accidentally Scientific techniques, including the analysis of charred. Rapid burial and decay of soft tissues and biological remains and the sediments that preserve the presence of semi-waterlogged conditions may all them, contribute greatly to the study of past land- be involved in the replacement of plant and animal scapes and economies and, at the site-specific scale, tissue with calcium phosphate or calcium carbonate. the interpretation of contexts and features. In this Once replacement has occurred, subsequent drying paper a summary of the types of evidence that have out has little effect on the remains. In waterlogged been studied in Somerset is presented, followed by a sediments such as wet ditch fills, valley sediments or brief overview of what they tell us about prehistoric peat bogs, survival of non-charred organic remains is vegetation change. often good, so long as the waterlogging existed at the time or shortly after burial. The larger plant remains such as wood, fruits, seeds, leaves and stem frag- Preservation ments, often referred to as plant macrofossils, are useful sources of information on a range of diverse Given suitable preservation conditions a wide range topics such as past diets, building materials, the use of biological remains can survive, but as Table 10.1 of plants for industrial processes such as dyeing, on page 61 and page 63 shows, most of the studies farming practice and local environments. from Somerset have concentrated on pollen, plant macrofossil remains and animal bones. Figure 10.1 Water-lain deposits can preserve diatoms (unicel- on the next page shows the location of past studies; lular algae, with frustules of silica) and foraminifera site numbers (in square brackets) referred to in the (brackish and marine protozoans, some of which text relate to those on this map and in Table 10.1. secrete a test of calcium carbonate). Ostracods, On dry-land sites, preservation can be restricted and small crustaceans principally found in freshwater plant remains survive usually because they became conditions, survive where the sediments are neutral accidentally charred. Charred preservation is usually to alkaline. These three organisms are useful in the restricted to cereal grain, chaff and weed seeds, with understanding of past water conditions, and diatoms rare examples of roofing material and animal fodder and foraminifera are also important indicators of surviving in a burnt state. This was the case at salinity levels and tidal regimes. Kenn Moor [2], where the only example of Roman Pollen grains, with their resistant exine of hay from south west England was identified (Jones sporopollenin can be preserved in a range of sedi- nd). Occasionally, seeds, fruits or arthropod remains ments. Pollen and spores survive best in anoxic, are “mineral-replaced”, a type of rapid fossilisation, acid conditions where oxidation and attack by micro- 59 60 Vanessa Straker Figure 10.1: Environmental studies from archaeological sites in Somerset organisms is reduced. As it usually survives well can learn about past diets, and dietary preferences, in peat, pollen has been well studied in parts of farming practice, fishing and wildfowling and the Somerset and has made the greatest contribution to former presence of animals and birds that are rare or our current knowledge of Somerset’s past vegetation. extinct in the area today. The study of wild animals complements the information gained from pollen Insect remains also survive well in peat and and plant macrofossil analysis on, for example, the organic silts, but not in dry sediments. They too former extent of woodland. Small mammals are have been well studied in the Somerset peat moors useful indicators of local micro-environments. of the Brue valley where they have been used to infer Snails survive in similar conditions to bones as the ground surface conditions and vegetation. At Meare shells are composed of calcium carbonate. Snails Village East [49] a degree of beetle infestation in have specific habitat requirements and colonise celtic beans (Vicia faba var. minor) gave an idea of terrestrial, freshwater or marine environments. the condition of stored products (Caseldine 1988). Molluscs of economic significance include shellfish The Somerset Levels Papers publish many reports of such as oysters, scallops and mussels. site-specific pollen and insect analyses. Animal bones survive in parts of the county where the soils are not acidic such as in the limestone History of environmental studies soils and sediments of Mendip and the Polden Hills, and in coastal sand dune sequences such as at Sir William Boyd Dawkins drew attention to the Brean Down. Their principal contexts for recovery presence of a “submarine forest” at Porlock as long include caves and swallets, urban and rural settle- ago as 1890 but Clement Reid, who worked for the ments and castles. Animal bones include the remains geological survey, was as far as the writer is aware, of large mammals (eg cattle, pig, sheep, deer), small the first person to study remains of plants found mammals (eg shrews, voles), birds and fish and on excavations in Somerset. Sometime between amphibians. From the study of these remains, we 1910 and 1920, he was asked to examine remains Holocene environments 61 orams No Site name Period Dendro Pollen Plant Diatoms Ostracods F Snails Insects Animal Soils 1 Birdcombe Mesolithic • 2 Kenn Moor Roman • 3 Henley Wood, Yatton Roman • • 4 Court Hill cairn, Tickenham Bronze Age • 5 Chew Down ? Iron Age • 6 Chew Park Roman • • • 7 Waterloo Farm, Banwell Moor Iron Age, Roman • • 8 Banwell Villa Roman • 9 Star Villa Roman • • • 10 Bleadon Bronze Age/ Iron Age • • • 11 Brean Down peat Mesolithic • • • 12 Brean Down settlement Bronze Age • • • • • • 13 Brean sea defence Bronze Age, Roman • • 14 Burnham-on-sea Prehistoric (Meso, Neo) • • • 15 Charterhouse Warren Farm Bronze Age • 16 Cheddar Palaces Saxon/Medieval • • 17 Cheddar: Goughs Upper Palaeolithic • 18 Cheddar: Soldiers Hole ? • 19 Cheddar: Wookey Hole Roman • 20 Bracelet Cave Prehistoric, Roman • 21 East Twin Post Medieval • 22 Badger Hole Post glacial • 23 Priddy Prehistoric • 24 Tom Tivey’s Hole Prehistoric and later • • 25 Gordano Valley Prehistoric (inc. Late Glacial) • 26 Cadbury Congresbury Roman, Post Roman • 27 Glastonbury Lake Village and environs Iron Age, prehistoric (pollen) • • • 28 Glastonbury Tor Saxon, Medieval • 29 Glastonbury Wirral Park Farm Medieval • 30 Glastonbury, The Mound ? • 31 Glastonbury: Beckery Chapel Saxon • 32 Glastonbury: Benedict Street Prehistoric-Roman • • • • 33 Glastonbury: Silver Street Medieval • • 34 Glastonbury: Wells Road Prehistoric-Post Roman • • • • 35 Glastonbury; Abbey Saxon • • 36 Abbots Way Neolithic • • • 37 Baker Neolithic • • 38 Brushwood Neolithic • • 39 Decoy Pool cover Neolithic • 40 Diffords ground Prehistoric • • • • 41 East Moors Prehistoric • 42 Eclipse Bronze Age • • 43 Franks ground Neolithic • • • 44 Garvins Neolithic • • 45 Godwins Bronze Age • • 46 Ham Walls Prehistoric (Meso, Neo) • • • • • 47 Honeygore Prehistoric • 48 Meare Heath Bronze Age • • • 49 Meare Village East Iron Age • • • • • 50 Meare Village West Iron Age • • • • • • Table 10.1: Environmental studies from archaeological sites in Somerset (continued on page 63) 62 Vanessa Straker from the Glastonbury and Meare lake villages, which been successfully carried out in South West England, included “cakes” or “buns”. In one example from and most of that has been from Somerset, prin- Glastonbury he noted “whole unbroken wheat grains cipally from the wooden trackways of the Brue with a noticeable proportion of glumes and frag- Valley, but also from “bog” oaks (eg Glastonbury ments of awn” and speculated that the mixture had [32] and at Stolford [67] in Bridgwater Bay. The been kneaded out of a mixture of wheat and “some- recent expansion of development-led projects has thing sticky, probably honey”. He also observed that meant that there is now an extensive “grey” liter- “it does not appear to have been much baked, as there ature of unpublished archaeological reports, which is no sign of crust or of burning” (Bulleid 1926, 68– may be slow to publication. Full references to 9). Later study of these by Hans Helbaek showed all the specialist reports cannot be presented here, that they comprised not only wheat and barley, but and the reader is referred to Bell (1984) which also seeds of field weeds too (Helbaek 1952). reviews much of the evidence prior to that date and The foundation for the study of past landscapes the Environmental Archaeology Bibliography which in Somerset was laid by the remarkable work of Sir is available through the English Heritage website Harry Godwin, starting in the 1930s. He developed (http://www.eng- h. go v.u k/ EA B/ ) . the studies of pollen analysis and peat stratigraphy Figure 10.2 on page 65 gives a chronological which have been invaluable in providing a picture of breakdown of the most frequent types of palaeoenvi- landscape development in the wetlands of Somerset, ronmental study (pollen, plant macrofossils, animal and an environmental context for the finds of wooden bones, snails and insects) but some of the data is trackways which were starting to be recognised. His difficult to present graphically. Many of the pollen work was built upon by the Somerset Levels Project analyses associated with the trackways of the Brue where the inclusion of an environmental archaeolo- Valley, for example, concentrate on the periods asso- gist as a permanent member of the project team set ciated with the tracks, but may also investigate the example for British archaeology. in part the sequences pre- and post- dating them. Virtually all of the environmental studies in The longer environmental sequences, which relate Somerset have been done in the last 30 years, and principally to pollen and plant macrofossil analyses most in the last twenty. The location of these studies are included in the “Prehistoric”, “Prehistoric to is shown in Figure 10.1 on page 60, and it is immedi- Roman” and “Prehistoric to post Roman” columns.