Bective excavations Blog


The Plant Macrofossil and Charcoal Remains from Bective Abbey by Sarah Cobain
July 4, 2010, 7:56 pm
Filed under: Uncategorized

Introduction

The survival of seed and charcoal macrofossils from dryland archaeology sites is usually dependant on the water table being high enough to keep the archaeological features in damp/wet and anoxic conditions.  This does not usually occur on archaeological sites in Ireland, unless they are located on riverine flood plains or close to lakes.  Seeds and charcoal are however preserved abundantly in the form of charcoal and carbonised plant remains as a result of burning activities in features such as hearths, kilns, furnaces, burnt structures and as waste material disposed in ditches and pits.

Bective Abbey, Co Meath was one of the first Cistercian Monasteries founded in 1147 by Murchad Ua Máel-Seachnaill in 1147 as a ‘daughter house’ of Mellifont Abbey and was excavated as part of the Irish Archaeological Field School summer excavations in July 2009 (Stout and Stout, 2009, 9). The excavations revealed a post-medieval structure and 17th Century ditch as well as a medieval building and external drain which was enclosed by a medieval ditch (Stout and Stout, 2009, 6).  Plant macrofossil and charcoal remains provide valuable information to determine socio-economic activity on archaeology sites.  It is the aim of this report to identify the seed and charcoal species recovered from the site at Bective Abbey and to use this information to:

1)    Provide additional information regarding the function of features sampled

2)    Interpret the diet and living conditions of the occupants of the site

3)    Interpret socio-economic and industrial activities on the site

4)    Infer the composition of the local flora and woodland

Methodology

There were 5 samples to be analysed for plant macrofossil and charcoal remains from Bective Abbey.  The following methodology was used to identify the plant macrofossil and charcoal remains.

Charcoal

The number of charcoal fragments to be identified is dependent on the diversity of the flora.  A study by Keepax (1998:120-124) has indicated that depending on the location of the archaeology site, 100-400 fragments of charcoal would need to be identified in order to obtain a full range of species diversity.  As Britain and Ireland have a narrow flora diversity in comparison to that of mainland Europe, an identification limit of 100 fragments has been deemed sufficient for samples from either of these two countries (Keepax, 1998 cited in Austin, 2005:1).  The majority of the samples contained less than 100 fragments, therefore in accordance with Keepax (1998) all fragments were identified.  Of the samples which contained greater than 100 fragments these were sieved through a 10mm, 4mm and 2mm sieve and an equal proportion of each sieve were identified.  This is to prevent any bias that may occur if only larger pieces are identified (thereby ensuring any potential smaller species are equally represented).

Each charcoal fragment was fractured by hand to reveal the wood anatomy on radial, tangential and transverse planes.  The pieces were then supported in a sand bath and identified under an epi-illuminating microscope (Brunel SP400) at magnifications from x40 to x400.  The sand bath allows the charcoal pieces to be manipulated into the flattest possible position to aid identification.  As fragments less than 2mm in size cannot be accurately identified (it is not possible to get a wide enough field of vision to encompass the necessary anatomical features for identification) only fragments above this size were examined.  During identification, any notable growth ring characteristics, evidence of thermal and biological degradation and any other unusual microscopic features were recorded.  Identifications were carried out with reference to images and descriptions by Cutler and Gale (2000) and Heller et al. (2004) and Wheeler et al. (1989).  Nomenclature of species follows Stace (1997).

Plant macrofossils

Plant macrofossil remains were retrieved by standard flotation procedures by CRDS Ltd using 1mm and 250 micron sieves.  The floated material was sorted and seeds identified using a low power stereo-microscope (Brunel MX1) at magnifications of x4 to x40.  Identifications were made with reference to Cappers et al. (2006), Berggren (1981) and Anderberg (1994). Nomenclature follows Stace (1997).

Results

The plant macrofossil and charcoal results are fully tabulated in Tables 1-2 in the Appendix at the end of the report.

Charcoal identification notes:

Where the charcoal species have been identified to (a) sessile/pedunculate oak; (b) Maloideae species (hawthorn/rowan/crab apple); (c) poplar/willow; (d) wild/bird cherry; (e) poplar/willow this is due to anatomical similarities between the species which prevented a definitive identification.

Plant macrofossil identification notes:

Upon identification of the carbonised cereal grains there were a high proportion of indeterminate fragments and grains.  Most of these grains had been subjected to high levels of mechanical abrasion (most likely caused by the stony and gravelly subsoil and post-depositional processes), which had caused the outer layer of the grains to become damaged, removing identifiable characteristics and preventing full identification.

Square A

Drain, F23

There were two fills taken from drain F23 for plant macrofossil and charcoal analysis.  Samples 82 and 91 were retrieved from fill F9 of drain F23 and contained a single uncharred elder seed, carbonised oat, wheat and barley cereal grains and carbonised pulse seed.  A charcoal rich fill, F20 (sample 61), was retrieved from the east end of drain F23 and contained carbonised oat, wheat and barley cereal grains, carbonised cereal chaff (culm nodes and rachis) and carbonised mustard/cabbage, vetchlings, pulses, tufted vetch, common vetch, sheep’s sorrel, wild radish and goosegrass seeds.

Square B

Occupational debris related to post pads, part of structure F23

Deposits F26 and F27 were retrieved from occupational debris layers assocaiated with the foundation trench fills and post pads part of structure F23.  Deposit F26 (sample 73) contained carbonised oat, wheat and barley cereal grains, carbonised cereal chaff (culm node) and carbonised field gromwell, mustard/cabbage, common vetch and common sorrel seeds.  Samples 92 and 103 were retrieved from deposit F27 and contained carbonised oat, wheat and barley cereal grains, carbonised chaff (broken awns, rachis and straw) and carbonised field gromwell, mustard/cabbage, vetchlings, tufted vetch, sheep’s sorrel, wild raddish and goosegrass seeds.

Discussion

Function of Features Sampled

The carbonised cereal grains, chaff and plant macrofossil material recovered from drain F23 and occupational debris deposits F26 and F27 are indicative of rake-out waste from cereal drying kilns, ovens and hearths that have been deliberately disposed of in the drain/foundtion trench of the building.  Although there is no evidence of insitu burning (kiln, hearths or ovens) in the excavated areas, further excavation in subsequent field school years could uncover evidence of cereal processing activity.

Economic and Industrial Activities

Cereal production and processing

Cereal crops have been a staple food source since their introduction by pioneering farmers during the Neolithic period.  Wheat and barley were commonly cultivated cereals during the Neolithic and Bronze Age periods and the cultivation of oats began during the Iron Age.  All these cereals have continued to be farmed through the medieval period up until the present day.

Crop husbandry played an important role in medieval society in regards to both use and consumption within the local community and as an economic resource for trade.  The prevailing damp climate during the medieval period meant that the grain would have been damp when harvested, so needed to be dried before any further processing could take place.  This drying halted any possible germination of the grain, prevented decay and made the grain easier to mill (Gibson, 1989:219).  Cereal drying kilns would have therefore been essential to arable farmers during this time.  All of the cereal remains from Bective Abbey were retrieved in a carbonised form as waste material within the fills of gully F23 and occupational layers F26 and F27.

As cereal harvests were a valuable commodity, care would have been taken not to waste any of the grain, however there were several mechanisms by which the cereals became carbonised. One possibility was grains accidentally falling into the fire pit areas of cereal drying kilns whilst being laid out on racks for drying.  Grains may also have been swept up with waste accumulated during the threshing and winnowing stage and burnt on the fire.  Another mechanism occurred as a result of sparks from the stoking/fire pit which entered and subsequently ignited material within the drying chamber.  The resulting fire would have carbonised all the cereal within the kiln.  This burnt waste would then be raked out from the cereal drying kiln and disposed of in pits, ditches and gullies.

Once the grain was dried, there were several stages of processing that had to be undertaken before it was ready to be used

1) Threshing – to break the ears of grain from the straw

2) Winnowing – throwing grain into the air to allow the breeze to blow away lighter chaff (paleas, lemmas, awns)

3) Coarse, medium, fine sieving and final hand picking of the grain (Stevens and Wilkinson, 2003:196-7).

was occasional carbonised cereal chaff recovered from the medieval deposits suggesting that crop processing was being undertaken on or near to the site, although excavations in subsequent years should provide further evidence to support this assumption. There

Trade

The Cistercians were one of the new monastic orders, which developed in the twelfth century.  Their economy was based on self-sufficiency and was dominantly reliant on arable agriculture (Stout, 202:86).  The cereal cultivated at Bective Abbey would have been used to feed the inhabitants and any surpluses produced were transported for trade both within Ireland, Britain and mainland Europe.  The location of the Abbey close to the banks of the River Boyne and at the fording points of the Ath an Sidhe (ford of the fairies) and the Beal an Atha (mouth of the ford) roadways to the north and south respectively would have made transport of these cereals to the port at Drogheda an efficient option (Moore, B. 1961, 63 cited in Stout and Stout 2009, 9).

Diet and socio-economic activities

Cereal consumption

As discussed above, any of the remaining grain that was not transported and traded would have been consumed by the local community.  The Bretha a Déin (Judgements of Dían Décht) – a law tract/medical treatise used throughout the medieval period exemplified that oat, barley and wheat were all cultivated in Ireland and all formed a staple part of the medieval diet (Hannon et al., 1991:72-73).  This legal text also demonstrates that there was a difference in the types of grain that was consumed by those of different status in society – it was asserted that the wheat was consumed by high status members of society and the barley and oats but those of lower status (Edwards, 2000:60).  The reason wheat was reserved for the higher status members of society was that the mild damp climate resulted in poor wheat harvests compared to those of oat and barley (Edwards, 2005:267-268).  The more nutritious wheat was therefore reserved for the kings, bishops and wealthy land owners.

The cereal grains recovered from Bective Abbey consisted of oat, barley and wheat with a dominance of wheat.  The high percentage of wheat indicates the high status of the occupants of Bective Abbey and also acknowledgment that wheat was a highly profitable trade item during this period. The oats and barley would also have been traded, albeit with less profit than wheat, however most of these cultivated these cereals would most likely have been consumed by local peasants and workers and used for fodder.

Once dried and processed, grain would be used to make a variety of foods including porridges, bread and cakes.  Wheat would have been milled and the flour used to make bread, cakes, tarts and pies.  It was also used as a thickener in sauces and soups, as stuffing for various meat dishes and also in the production of sausages (Adamson, 2004:2).  Oats were easy to grow and were considered ‘poor man’s food’ by the rich.  They were used to make Littiu (a porridge made with oats and combine with water, buttermilk or new milk), unleavened bread or oat cakes (Sexton, 1991:76).  Oats were also the main ingredient of pottages, which was one of the dominant foods consumed by the poorer members of society (Stone, 2006:13).  Barley produced a heavier, denser bread which was considered ‘inferior’ to wheat bread by those of higher status, therefore it was more commonly consumed by lower status members of society.  It was also grind down and made into porridge (Adamson, 2004:3).

Beer production

Cereal crops were regularly used to brew beer during the medieval period.  Dyer (1983) cited in O’Keefe (2001:68) suggests that up to one gallon (3.79 litres) of beer would be consumed per person per day.  A reason for this is because of poor water sanitation during the medieval period, which meant beer would have been consumed in preference to water to avoid contracting water borne diseases (eg cholera and dysentery).  Beer would also have been consumed for social aspects and would also have been an added source of vitamins and calories (Galloway, 1991:87). Whilst wheat, oats and barley would have been processed to produce beer, barley was the most frequently used as it produced the best malt (Stone, 2006:13).  Wheat, although it produced a far better-quality brew, was usually reserved for bread production rather than being used for brewing.  Ale was brewed from oats, although it had a distinctive taste, described in the sixteenth century to be ‘lyke wash as pygges had wrestled dyrn’ (Fox, 1991:304 cited in Stone, 2006:13) so was not favoured and barley was used if at all possible.

It is possible that beer production was being undertaken at the site at Bective Abbey, however none of the cereal grains recovered were sprouting.  In order to produce ale, the harvested cereal crop is soaked in water to allow it to germinate.  The sprouting grain is then removed from the water and roasted in a cereal drying kiln to halt the germination process (Stone, 2006:15).  If ale production was being carried out on site it would be expected that a few of the sprouting grains would become accidentally carbonised within the cereal drying kiln and recovered in the plant macrofossil assemblage.  It is possible that damage may have occurred to the grains when they were being raked out of the cereal drying kilns and discarded into ditches/pits making it impossible to identify signs of germination, however with the size of assemblage recovered, it is unrealistic to imagine no sprouting grains survived.

Additional uses for cereal crops

Cereal crops (in particular oats and barley) would have been used as animal fodder (Pearson, 1997:3) and the by-products of grains were also put to use, for example cereal straw was used for bedding for humans and livestock and also as a component of building materials such as thatch, daub, flooring and insulation.

Herbaceous taxa

Herbaceous plants were often exploited to be used as herbs in cooking, vegetables or eaten raw in salads, all of which would have helped add flavour to food and to provide vitamins, minerals and additional fibre.

Herbs, vegetables and salads

Dock, sorrel, wild raddish and cabbage/mustard have all been recorded as being eaten raw as salad, boiled down and used as pottage in stews and soups and as vegetables similar to spinach (Pfaf, 2010, Pearson, 1997:11, Behre, 2008:67-8).  The seed pods and leaves of goose grass/cleavers can also be used as a substitute for spinach if boiled and their seeds can be roasted and ground down to make coffee (Mabey 2007:70).  Pulses and vetches were also retrieved on the site and are recorded to have been used to thicken stews and as additions to pottages (Harvey, 1984:91). In times of poor harvest, they are also known to have been milled along with wheat/barley/oat flour to make bread (Renfrew, 1985:17).

Fruits

Elderberries and flowers had many uses and were regularly exploited throughout history.  Elderberries/flowers were boiled down and used to make mousses and jams/jellies and were also used in juices and to make wine (Aitkinson and Aitkinson, 2002: 916).

All these species have been recorded as being used as food through documentary sources, analysis of archaeological ecofacts and also information based on foods we eat today.  Their inclusion within the plant macrofossil record at Bective Abbey may purely be indicative of weed species establishing in disturbed areas of the site, however it cannot be disregarded that some of these species were being exploited and consumed. The reason for this is that there has been direct evidence of herbaceous taxa being consumed.  Macrofossil analysis from the stomach contents of bog bodies such as Kayhausen (Oldenburg, Germany) the Grauballe man (Jutland, Denmark), the Tollund man (Jutland, Denmark) and the Lindow man (Lindow Moss, Cheshire, Britain) have shown indicated the presence of species such as dock (Rumex crispus and Rumex acetosella), cabbage/mustard and cereals (barley and wheat), within the stomach contents of these people when they died.  This suggests that these species were particularly selected for consumption (Behre, 2008:67-68).  Although these bog bodies were from various countries (Germany, Denmark, Britain) as these taxa were all found in Ireland during the medieval period, it can be assumed that they would have been selected and consumed (or processed to use in/or with cooking food) in Ireland.

Medication and Drugs

Herbs were frequently experimented with during the medieval period to produce medication and treatments for all kinds of ailments and also drugs for recreational enjoyment.  Elder flowers, leaves and berries also had herbal medicinal uses and were used to treat inflammation, bruises and wounds (Atkinson and Atkinson, 2002:916-917).  Mustard/cabbage was particularly easy to grow – indicated by its relatively high representation at Bective Abbey and its ‘hot and dry’ flavour was thought to be good for removing phlegm from the body (thereby treating colds and flu) and sorrel was considered a good cure for coughs (Crellin et al.DATE:394). Goosegrass/cleavers also had several functions. Its juices were used to clean the lymphatic system, thereby reduce swollen glands and treating certain cancers and it was used to cleanse wounds and protect against eczema (Press, 2002:62).  Although all the seeds within this assemblage were recovered in relatively small quantities, the use of herbalism during the medieval period was an important part of society, therefore it is possible that any/all of these were being used to ‘treat’ the local community. It is possible that this gives some additional evidence towards the use of the structure as an infirmary (Stout and Stout, 2009, 7) however a larger plant macrofossil assemblage would be required to confirm this.

Industrial Activities

The roots of goose grass/cleavers are known to be used to make a red dye, which may have been used to dye clothing (Pfaf, 2009a), although as this species was only recovered in very small numbers, it is not possible to confirm whether they were being used for this function.

Collection methods of herbaceous taxa

The method of collection of these herbaceous taxa is however less conclusive – as all these species were recovered in relatively low numbers, it is uncertain whether they were obtained by trade, deliberately cultivated, handpicked from the local environment or weed species associated with arable agriculture.  It must also be considered that all the macrofossils were recovered carbonised – as the process of carbonisation removes all nutritional value from plant material, care would have been taken to ensure any harvested herbs would not be damaged through accidental burning or loss, therefore their low abundances cannot be automatically used to discount their use.

Many of these species were likely to have been handpicked from the local environment, which would have provided a cheap way of obtaining the raw materials required for industry, medicine and also for additional dietary supplements.  Excavations of medieval gardens in Hull, England (Sewer Lane and Scale Lane) have also provided evidence that some species such as cabbage/mustard, elder and dock/sorrel were being deliberately cultivated and harvested for food and other industrial and medicinal processes (Crackles, 1986:2-5).  As the climate in Britain and Ireland was similar during this period there is therefore no reason why at least some of these species were not being cultivated and used here.  Another method of obtained these species would have been through trade.  As asserted by Comber (2001:73-74), trade networks had hugely increased by the early medieval period and in particular the location of the site at Bective Abbey on the river Boyne and at the fording points of the Ath an Sidhe (ford of the fairies) and the Beal an Atha (mouth of the ford) roadways would have allowed increased availability of goods.  Therefore likely that some of these species would have been exchanged or brought through traders.  It is also likely that some of the seeds which have been recovered could have been brought onto the site inadvertently with cereal crops.  Without specific documentary evidence as to how all these taxa were obtained, it is therefore reasonable to assume that the woodland/scrub, herbaceous taxa and cereals found at the Bective Abbey were obtained by a mixture of these three methods.

Composition of local woodlands and flora

Local woodlands and flora – Evidence from plant macrofossils

Woodland species

The only woodland macrofossil species recovered from Bective Abbey was a single elder seed.  Elder trees grow as part of alder-carr scrub that grows on waterlogged/damp soils (Aitkinson and Aitkinson, 2002:897, 900 and McVean, 1953:450) and are species which would have grown on the floodplain of the river Boyne.

Submerged/marsh/fen water plants

There were no submerged water or marsh/fen species recovered from the Bective Abbey plant macrofossil assemblage.

Opportunistic/ruderal species

Cabbage/mustard, field gromwell, dock and sorrel are all opportunistic species which grow well on cleared/waste ground (Williams, 1963:713, Crackles, 1986:4, Mitich, 1997:844, Cavers and Harper, 1964:758, Greig-Smith, 1948:352, 388, Sobey, 1981:311).  These species all could have grown easily within the Bective Abbey site, taking advantage of cleared areas and waste ground on the sides of the monastery and adjacent to tracks leading the site.  Whilst these are all considered ‘weed’ species, it cannot be disregarded that these were all common food sources during this time, so their abundances within the archaeological features could have been a mixture of both their consumption and presence growing (either opportunistic or deliberate cultivation) in and around the site.

Dryland species

Goose grass, vetchlings, pulses, vetches and wild radish are all species that would have grown in dry areas or in cultivated arable areas (Kay, 1971:623, Holland, 1919:9-10, Dickson, 1996:26-27).  It is possible that these would have been inadvertently been brought into the site with the cereal crops that were being processed and hence become accumulated with waste within the fire pits of the kilns and subsequently into the drain and occupational debris layers.

References:

Appendix

NB: All plant macrofossil material is carbonised unless marked with an *.

Sample Number 61 73 82 91 92 103
Feature Number (Fill) 20 26 9 9 27 27
Flot Volume (ml) 81 33 52 31 5 16
Family Species Common Name
Adoxaceae Sambucus nigra Common elder 1*
Boraginaceae Lithospermum arvense Field Gromwell 43 1 3
Brassicaceae Brassica spp Mustard/cabbage 92 18 6 16
Raphanus raphanistrum Wild radish 12 1 1
Fabaceae Lathyrus spp Vetchings 10 3
Lens culinaris Pulse 8 1
Vicia cf cracca Tufted cf vetch 6 5
Vicia cf sativa Common cf vetch 44 15
Poaceae Avena spp Oat 126 30 3 7 13 20
Hordeum spp Barley 80 5 8 3 3 12
Triticum spp Wheat 50 5 5 7
Triticum aestivum/ durum Wheat – naked/free threshing 482 6 26 22 32 68
Triticum dicoccum Wheat – emmer 48 1 1 1
Triticum monococcum Wheat – einkorn 28 1 1
Triticum spelta Wheat – spelt 140 14 13 19
Poaceae Indeterminate grain 1070 74 43 30 112
Poaceae Indeterminate chaff – awn freq
Poaceae Indeterminate chaff – culm node 12 1
Poaceae Indeterminate chaff – rachis segment 2 2
Poaceae Indeterminate chaff – straw 3
Polygonaceae Rumex acetosa Common/garden sorrel/spinach dock 2
Rumex acetosella Sheep’s/field sorrel 6 2 2
Rubiaceae Galium aparine Goosegrass 2 1
Total macrofossils 2218 121 127 94 94 276

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