Zutter, Micro Macrorrestos

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Journal of Archaeological Science (1999) 26, 833844Article No. jasc.1998.0349, available online at http://www.idealibrary.com on

Congruence or Concordance in Archaeobotany: AssessingMicro- and Macro-botanical Data Sets from Icelandic Middens

Cynthia Zutter

Department of Social Sciences, Grant MacEwan College, Edmonton, AB, T5J 452, Canada

(Received 26 May 1998, revised manuscript accepted 11 September 1998)

Archaeological farm middens dating from the Viking Age to early modern times are found throughout the NorthAtlantic region and contribute information regarding past ecological and economic conditions. Archaeobotanicalinvestigations of two Icelandic farm midden sites are interpreted for plant-use trends in this northern pastoral economicsystem. Macro-botanical (i.e., seeds, leaves) and micro-botanical (i.e., pollen) remains are compared in order to assessthe degree of congruence between these differing data sets. The background signature of macro- and micro-botanicalvariability in Icelandic pastoral practices is established through the analysis of present-day farmyard contexts for the

assessment of diff

ering archaeobotanical remains. Results indicate micro- and macro-botanical remains from Icelandicarchaeological sites are not congruent since plants and plant parts are differentially collected and utilized by humansand these patterns of plant-use will effect whether or not micro- or macro-remnants are incorporated into thearchaeological record. 1999 Academic Press

Keywords: ARCHAEOBOTANY, MICRO-BOTANICAL, MACRO-BOTANICAL, ICELAND.

Introduction

S

ince the 1960s, retrieval of botanical remainsfrom archaeological sites has become an integralmethodology utilized by archaeologists to assist

in the reconstruction of past lifeways (Bohrer &Adams, 1977; Ford, 1979; Bryant & Holloway, 1983;Pearsall, 1989; Lennstrom & Hastorf, 1995). Macro-botanicals (e.g., seeds, chaff, leaves, stems, wood frag-ments) are the most common type of archaeobotanicalsanalysed, as these types of materials are highly visible,likely to be recovered and assumed to directly reflectcultural uses of plants (Ford, 1979; Minnis, 1981;Hastorf & Popper, 1988; Pearsall, 1989). However,conditions on archaeological sites are not alwayssuitable for the preservation of abundant macro-botanicals. This is the case for archaeological sites intemperate areas, like Iceland, with intense freeze/thawconditions.

To address the problem with macro-botanical pres-ervation, studies have been conducted that correlatemicro-botanicals (i.e., starches, phytoliths, pollen) withmacro-botanicals as an effective way to investigate theeconomic importance of plants and the importanceof plants in the past diets of humans and theirdomestic animals (Bryant & Williams-Dean, 1975;Moe, 1983; Fredskild & Humle, 1991; Hnorzer, 1991;Rasmussen, 1991, 1993; Greig, 1994; Robinson &Aaby, 1994; Smith, 1997). The basic assumption ineach of these cases is that there is some form of

agreement, or congruence, between macro- and micro-archaeobotanical remains. Micro-botanical remainsare assumed to be simply a different type of archaeo-botanical that correspond to the macro-botanicalremains (Sutton, 1998). However, the congruity

between macro- and micro-archaeobotanical remainshas rarely been analysed and is a current topicof interest within the palaeoethnobotanical com-munity (Zutter, 1998). This paper focuses oninvestigating the congruence between macro- andmicro-archaeobotanical data sets from two Icelandicfarm midden sites.

The Svalbar and Gjogur Sites

Bordering on the Arctic circle, Iceland is often consid-ered to be on the fringe of productive agriculture.Despite this, Norse Vikings and their retinues settledon this island in the 9th century and established a

productive agrarian economy that continues today.Plants were a fundamental resource of the NorseIcelandic agrarian economy supplying summer grazeand winter fodder for livestock as well as a source offood for human consumption.

The archaeological middens, Svalbar (661312 N, 54224 W; 20 m a.s.l.) and Gjogur (66 N,212208 W; 45 m a.s.l.) (Figure 1) are ideal forarchaeobotanical investigations, since they are at least2 m deep, have well stratified deposits with minimaldisturbance and demonstrate continuous use from the

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11th to 18th centuries (Amorosi, 1992; McGovern &Amorosi, 1988). Excavated in 1988 and 1990, respect-ively, the Svalbar and Gjogur middens were a favour-able context for the retrieval of archaeobotanicalmaterials. These sites are located in isolated regions ofthe island where agrarian practices, even today, areoften inhibited by fluctuating environmental con-ditions, such as the year-round occurrence of sea ice,which lowers temperatures and shortens the growingseason (Fririksson, 1978)

Archaeological finds from Svalbar indicate that theeconomy was based primarily on animal husbandrypractices, with some degree of fishing and sea mammalhunting (Amorosi, 1992). Caprines, mainly sheep, were

the dominant type of domesticate throughout theoccupation of the Svalbar farm, while cattle werenumerous during the 11th and 12th centuries butdeclined in number after the 13th century. Post-13thcentury deposits contained significant quantities of seamammals, fish and molluscs, representing importantsurvival foods (Amorosi, 1992). Cereal agriculture isnot apparent, as there were no grain processing imple-ments (i.e., sickles, querns, grinding stones) or carbon-ized cereal grains excavated from the archaeologicaldeposits (Zutter, 1992).

The close proximity of the Gjogur farm to theproductive North Atlantic Ocean facilitated a com-bined economy based on fishing and animal hus-

bandry. Preliminary results from the midden indicatethat fish, especially cod, were abundant throughout theoccupation of the farm, as were caprine (i.e., sheep)domesticates. Birds and seals were also common in theearly settlement and early modern deposits, and thereis no artefactual or archaeobotanical evidence of arableagriculture (McGovern & Amorosi, 1992; Zutter,1997).

To facilitate easier correlation of the macro- andmicro-botanical results, relative percentage diagramswere constructed using Tilia and Tilia graph computer

programs (Grimm, 19911993) and all samples weregrouped into three time periodsthe Settlement/Mediaeval (SM) ( 10501250), Late Mediaeval (LM)( 12501600) and Early Modern (EM) (post-1600)that were extrapolated from dated tephralayers and diagnostic artefacts in the midden deposits.

Icelandic tephras provide reliable chronologicaltimelines, with well-established sequences of datedtephra layers from all areas of the island (Dugmore &Buckland, 1991).

Methods

Archaeobotanical samples (i.e., pollen and macro-botanicals) were collected from the sediment of theSvalbar and Gjogur middens in stratigraphic levelsthat correlated to those of the archaeological exca-vations. Collection procedures followed well-

established methods (van der Veen & Fieller, 1982;Wasylikowa, 1986; Pearsall, 1989; Lennstrom &Hastorf, 1992). A series of samples were retrieved fromthe discrete strata in the richest, deepest area of eachmidden. A total of 17 and 15 macro-botanical sampleswere excavated from the Svalbar and Gjogur mid-dens, respectively. Small quantities of sediment weresubsampled from each midden sample for pollen analy-sis. Macro-botanical and pollen samples were alsoretrieved from various present-day farmyard contexts.

Two litre macro-botanical samples were processed todisperse mineral sediment and facilitate sorting ofidentifiable floral remains from indeterminable residue.Highly organic samples were soaked and gently heated

for 24 h in 005% sodium hydroxide before wet sievingthrough #20 (085 mm) and #40 (050 mm) mesh Tylerscreens (Wasylikowa, 1986). Sediments were examinedusing a low power binocular microscope 1250).Only charred or degraded macrobotanicals wereidentified while those with a fresh appearance wereconsidered modern contaminates.

Thirty-two pollen samples, 13 g dry weight, wereprocessed using a 10% sodium hydroxide, hydrofluoricacid to dissolve silicates and acetolysis to removecellulose (Fgri & Iversen, 1975; Moore, Webb &Collinson, 1991). Total pollen counts were between 300and 1000 grains per sample, in order to get relativelyconsistent pollen sums and a representative number of

plant taxa (Birks & Birks, 1980: 165). A standard Leitztransmitted light microscope was used for pollenanalysis and pollen identification was assisted by pub-lished keys (Fgri & Iversen, 1975; Moore, Webb& Colllinson, 1991), selected papers (Anderson &Bertelsen, 1972; Anderson, 1978; Foss & Doyle, 1988)and the extensive pollen reference collection ofthe Palaeoenvironmental Laboratory, University ofAlberta. Botanical nomenclature for macro- andmicro-botanicals follows Flowering Plants and Ferns ofIceland (Kristinsson, 1987).

North Atlantic Ocean

N0 50 km

Glaciers

Reykjavk

SvalbaroGjgur

ARCTIC CIRCLE

Figure 1. Map of Iceland with study sites.

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Results

Macro-botanical analysis

A total of 1442 macro-botanical remains representing23 taxa were recovered from the 17 Svalbar midden

samples (Zutter, 1989) (Table 1; Figure 2). Macro-botanical remains were dominated by leaves and seedsfrom heath taxa during the Late Mediaeval, withgrasses, weeds and sedges contributing low percentagesthroughout all time periods in the midden. Gramineaetaxa averaged 10% during the Settlement/Mediaevaland Early Modern periods, but were


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Figure 2. Svalbar midden relative percent macro-botanical diagram.


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small and used traditional methods of haying andfoddering their animals. Barn floor deposits, fresh hay,feeding trough remnants, barn midden deposits andcow manure and sheep dung from pastured animalswere each sampled for macro- and micro-botanicalremains. Barn floor materials in present-day farmsettings are deposited onto the barn midden, and it isassumed that similar barn cleaning events occurred inthe past, with materials ending up in the archaeologicalmidden deposits. It should be noted, however, that

when necessary, Icelandic farmers have historicallyused manure from the barn to fertilize the hayfields sothe archaeological midden deposits may not provide anannual record of barn cleaning events.

Results from the macro-botanical remains (Figure 6)indicate that the hay stores and trough remnants aredominated by apophytes (Montia fontana, Cerastium,Stellaria media, Silene) with combined values of 83%and few Gramineae seeds (15%). The outdoor middendeposits had almost equal percentages of grass (45%)and apophytes (50%). The barn floor deposits mirrorthe hay store sample, with 75% apophyte seeds and20% Gramineae seeds. Manure from rangeland grazingcattle consists of 30% Gramineae and 60% apophytes,

and sheep faeces are mainly Cyperaceae (50%) with20% Ericaceae undiff., 20% apophytes and 10%Gramineae.

Pollen percentages from present-day farm contextsdiffer quite markedly from the macro-botanicals, allhaving significant percentages of Gramineae (Figure7). The hay store, trough remnants and midden hadhigh Gramineae values (c. 9095%), the remaining510% representing apophytic pollen. The barn floorsample consisted of 70% Gramineae pollen, with 20%Cyperaceae and 8% apophytes. Cow manure consisted

of 75% Gramineae with


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Figure 3. Gjogur midden relative percent macro-botanical diagram.


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Figure 4. Svalbar midden relative percent pollen diagram.


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Figure 5. Gjogur midden relative percent pollen diagram.


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livestock manure indicates that the livestock were pref-erentially consuming high quantities of grass during theearly summer (Moe, 1983). The multitude of apophyticseeds in the hay and midden deposits suggests thatduring harvest apophytic taxa were already producingseeds that were not entirely digested by the livestock.

Pollen and macro-botanicals from heath taxa are onlyapparent in the manure from the free-grazing sheepfaeces, probably consumed in the early winter or springwhen few other resources are available.

Svalbar midden archaeobotanicals

During the Settlement period, pollen percentages indi-cate significant amounts of Gramineae hay fodder,along with a high percentage of Cyperceae which arelikely to represent hay collected from wetlands (Figure9). Historically, sedge hay fodder was often collectedfrom the abundant lowlying mires on the island butrecent practices of draining these mires through the use

of drainage ditches has created a grass dominated hay,similar to the present-day samples. Pollen values forthe Late Mediaeval and Early Modern are similarto the Settlement recorda mixture of Gramineae/apophyte/Cyperaceae taxa, with a gradual increase inGramineae.

The macro-botanical remains, dominated by heath-land taxa, differ markedly from the pollen percentages.Late Mediaeval macro-botanical deposits contain sub-stantial amounts (75%) of heathland taxapossiblyrepresenting Empetrum nigrum berries for human

consumption and Empetrum nigrum and Calluna vul-garis woody twigs for animal fodder and/or bedding.Cyperaceae and apophytic taxa are common in themost recent pollen and macro-botanical middensamples suggesting that fodder and manure depositsconsisted of abundant apophytic and Cyperaceae taxa.

Gjogur midden archaeobotanicals

Comparison of the Gjogur macro- and micro-botanicalsamples revealed consistently high values of Cyper-aceae pollen and heath (e.g., Empetrum nigrum) macro-botanicals with minimal Gramineae pollen (Figure 10).The abundance of Cyperaceae pollen suggests that hayfodder was collected mainly from wetland meadows,with some limited amounts of grass fodder. Heathlandpollen percentages indicate that heath did not coverlarge areas surrounding the farm, yet Empetrum nigrumand Vaccinium seeds and leaves were plentiful in the

macro-botanical record, especially during the EarlyModern period. These were probably collected asfodder or bedding for livestock and berries for humanconsumption (Buckland et al., 1991). During the LateMediaeval, apophytic macrofossils, including Ranun-culus acris, Taraxacum and Stellaria media, contrib-uted over 50% to the midden deposits. This suggests anincrease in the presence of weeds in the farmyard andless productive hay fodder from the 13th to 17thcenturies, possibly a result of Little Ice Age cooling inthe region (Meese et al., 1994).

Figure 6. Modern farmyard relative percent macro-botanical diagram.

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Conclusion

Comparing the results from the macro- and micro-botanical records in the Icelandic archaeobotanicaldeposits facilitated a more comprehensive reconstruc-

tion of plant-use practices in the past. It appears thatmicro-botanical analysis contributes important supple-mentary, not necessarily congruent, Icelandic archaeo-botanical information. For example, Gramineaepollen indicated that despite few macrofossil

Figure 7. Modern farmyard relative percent pollen diagram.

Macrobotanical

relativepercent

Pollenrelativepercent

Gjgur barnmidden

Gjgur haystore

Cowmanure

Sheeppellets

Figure 8. Modern farmyard botanical diagram. , Wetland; , apophytes/weed; , grasses; , heath shrubs.

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remains, it was an important part of the hayfodder and graze, especially at Svalbar. Similarly,Cyperaceae pollen suggests the use of sedge hayat Gjogur. Alternatively, the low pollen percentagesyet substantial numbers of macro-botanicals fromheath shrubs suggest that these were preferentiallycollected plants, providing sustenance for humans andanimals.

Overall, there does not appear to be congruencebetween the micro- and macro-botanical remains inIcelandic middens. Instead, each type provided data

regarding different Icelandic plant-use practices. Per-haps this should be expected, as plants and plant partsare differentially collected and utilized by humans andthese patterns of plant-use will effect whether or notmicro or macro remnants are encorporated into thearchaeological record. Consequently, palaeoethno-botanists should be cautious when assuming thatmicro-botanicals correspond to macro-botanicalremains on archaeological sites. The deposition pat-terns, production and preservation of different plantsand plant parts must be considered when interpreting

archaeobotanical remains. Further, it is evident fromthe Icelandic archaeobotanical results that relyingsolely on one type of botanical record from archaeo-logical middens would create a skewed interpretationof historic plant-use practices. Collection of multiplebotanical data sets from archaeological sites wouldhelp provide a more comprehensive archaeobotanicalrecord allowing for one to reconstruct the full range ofplants used in the past.

Acknowledgements

The farmers at Svalbar and Gjogur were very open-minded as I rummaged in their barns and middens. DrsTom McGovern and Tom Amorosi facilitated thecollection of these samples. Lastly, I greatly appreciateDr Charlie Schweger, Dr Alwynne Beaudoin and MikeMacKinnon for providing useful comments on earlierdrafts of this paper. Funding for this researchwas provided by a C-BAR grant from the CanadianCircumpolar Institute.

Macrobotanicalrelativepercent


Early Modern(post-AD 1600)

Late Mediaeval(c.AD 12501600)

Settlement/Mediaeval(c.AD 10501250)

Figure 9. Svalbar midden archaeobotanical diagram. , Wetland; , weeds/apopytes; , grasses, , heath shrubs.

Macrobotanicalrelativepercent


Early Modern

(post-AD 1600)

Late Mediaeval

(c.AD 12501600)

Settlement/Mediaeval

(c.AD 10501250)

Figure 10. Gjogur midden archaeobotanical diagram. , Wetland; , weeds/apopytes; , grasses, , heath shrubs.

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Zutter, Micro Macrorrestos