Integrating Zooarchaeology and Paleoethnobotany A Consideration of Issues, Methods, and Cases

A Tale of Two Shell Middens: The Natural
versus the Cultural in “Obanian” Deposits
at Carding Mill Bay, Oban, Western Scotland

László Bartosiewicz, Lydia Zapata, and Clive Bonsall


Composed largely of mollusc shells resulting from food procurement activities,
coastal shell middens have been regarded as valuable sources of information about
past human exploitation of coastal and marine resources. It is less widely appreciated
that these sites, which lie at the interface between the sea and the land, have
significant potential to inform us about the terrestrial environment and its resources.
In this chapter, an attempt has been made to integrate results of paleoethnobotanical
and zooarchaeological studies with existing archaeological knowledge concerning
Mesolithic and Neolithic environments and subsistence at a shell midden site on the
west coast of Scotland. We compare and contrast the information derived from
macrobotanical and vertebrate faunal remains from two locations at the site of
Carding Mill Bay. Although the midden deposits were also studied from the malacological
point of view, the shellfish remains are not considered here as they characterize
only the marine environment. Moreover, the terrestrial component of a
midden may tell us more about post-depositional taphonomic processes than the
marine component.
Carding Mill Bay I and II are the westernmost known sites in a cluster of
Mesolithic/Neolithic shell middens around Oban Bay (Fig. 1). Following the
discoveries made in caves in the area during the late 19th century (Anderson 1895,
1898; Bonsall and Sutherland 1992; Lacaille 1954), these sites were originally
believed to represent a discrete Mesolithic culture confined to the coastal areas of
central-west Scotland, which came to be known as the “Obanian culture” (Movius
1942). Subsequent research has cast doubt on this interpretation, and the “Obanian”
shell middens are now seen as simply one aspect of the Mesolithic maritime adaptation
in western Scotland (Bonsall 1996). Moreover, they do not belong exclusively
to the Mesolithic period (9500–3900 cal. bc); the deposition of shell middens containing characteristic “Obanian” bone tools continued in western Scotland into
the Neolithic period (3900–2500 cal. bc) and, possibly, as late as the Bronze Age
(2500–600 cal. bc) (Griffitts and Bonsall 2001). Faunal studies of several “Obanian”
sites have been undertaken, including the analysis of material from Carding Mill
Bay I (CMB I), which is located some 15 m south of CMB II. The excavation of
CMB I was undertaken in 1989, and the excavation report (Connock et al. 1993)
included a study of the vertebrate remains by Hamilton-Dyer and McCormick
(1993) as well as a report on the paleoethnobotanical remains by Boardman (1993).
Their detailed accounts permit comparisons with the animal and plant remains
recovered more recently at CMB II.
1 Materials and Methods
Carding Mill Bay II (CMB II) is located approximately 1.5 km southwest of Oban,
at latitude 56° 24¢ 26″ N and longitude 5° 29¢ 26″ W. Prior to its discovery, the site
was buried beneath the talus deposits that accumulated at the base of a raised
marine cliff. The cliff and the rock platform in front of it constitute a former marine
shoreline (known as the “Main Rock Platform”) that is particularly well developed in the Oban area. The site was discovered in 1988 when the talus deposits were
disturbed during construction work. Excavations, funded by Historic Scotland and
directed by Clive Bonsall, were undertaken between 1991 and 1993.
The site faces northwest and consists of a shallow natural recess in a near-vertical
rock face. The recess was infilled with sediments containing a variety of archaeological
remains. These could be divided into a series of lithologically distinct layers
(Fig. 2). Excavation was based on a 50-cm grid, and the deposits were removed in
horizontal unit levels (“spits”) of 5 cm thickness between layer boundaries. All
excavated materials were passed through a nest of sieves, with mesh sizes between
1 and 4 mm, while the material from one 50 × 50 cm grid square (Q5D) was treated
as a column sample and subjected to flotation and wet sieving using mesh sizes
down to 0.25 mm – the majority of the nonwood botanical samples were recovered
from this column.
Radiocarbon dates for the shell midden at CMB I range from ca 4010 to 3550
cal. bc, suggesting an Early Neolithic age, possibly extending back to the time of
the Mesolithic–Neolithic transition in western Scotland (Bonsall and Smith 1992;
Connock et al. 1993). The dating of the midden layers at CMB II is less well-documented.
Currently, no radiocarbon radiocarbon dates are available, and the artifact
inventories differ significantly from CMB I – for example, there are no bevel-
ended tools of bone or antler (see also Griffitts and Bonsall 2001) from either the lower or
upper midden of CMB II, though these were common in the CMB I midden. The
presence of pottery and bones of domestic livestock, especially caprines, in the
upper midden of CMB II indicates a post-Mesolithic date. The lower midden, however,
produced no pottery, and only a single bone from a domesticate was observed.
On the basis of the pottery typology, the upper midden is provisionally assigned to
the Late Neolithic; the lower midden could date earlier in the Neolithic or, if the
single sheep/goat (Ovis/Capra spp.) bone was not in situ, to the Mesolithic.
However, differences in the artifact and faunal inventories of the midden deposits
at CMB I and II (see below) may indicate that the respective middens belong to
different periods in the human use of the Carding Mill Bay locality.
An initial set of samples was retrieved by wet sieving. The Q5D “column” was
processed separately at a later date, primarily for the recovery of macrobotanical
remains and land snails. This yielded a vertical series of 58 individual samples, each
comprising material from a single 5 cm-thick “spit.” The paleoethnobotanical material
was recovered by flotation in the laboratory using a 0.25 mm sieve. The residues
(heavy fraction or “retent”) from the flotation process were hand sorted in order to
retrieve other archaeological components (molluscs, small bones, lithic debitage,
etc.). The plant material that was found during this sorting was included in the paleoethnobotanical
sample. Some of the residues were double-checked by Zapata in order
to assess the effectiveness of the initial sorting, which was found to be adequate.
The processed flotation samples (light fraction or “flot”) were sorted under a lowpower
reflected-light microscope. Wood charcoal was identified using epi-illuminated
light microscopy. Schweingruber (1990) was used for identification and nomenclature.
Identification was facilitated by using a reference collection of modern carbonized
wood. All fragments of wood charcoal >2 mm were examined, which is usually
considered to be the minimum size when using anatomical features as criteria for
identification. Most fragments were close to this size, so the process was quite timeconsuming
and may have increased the number of problematic identifications.
Virtually all the identifiable animal bones were found in the 1–4 mm sieve fractions,
and these fractions were critical for the recovery of the remains from
microvertebrates. The <1 mm sieve fractions provided very few animal remains.
Even the recognized pieces (e.g., incisor splinters from rodents, fragmented fin
rays, branchyostegalia, and ribs from small fish) likely originate from identifiable
specimens encountered in the less finely recovered fractions. This falls in line with
experimental evidence that bone splinters shorter than approximately 20 mm have
a 95% chance of being missed when only hand collection is practiced (Bartosiewicz
1988; see also Peres, this volume chapter 9, for further discussion). The significance
of sieving is clearly illustrated by the example of fish bones at the site, of
which only a few large fragments ended up in the hand-collected sample of bones.
Evidently, fine sieving led to an increase in the number of nonidentifiable, small
fragments, but also resulted in a more complex faunal picture, especially in the
case of fish and rodents. As a convention, “cf.” is used here to signify that the
identification is not certain, but there is a very high probability of belonging to a
particular taxon (see also Peres, this volume chapter 9). 2 Study Results
2.1 Macrobotanical Remains
The types of remains recovered in the samples include: (a) wood charcoal, the most
abundant type; (b) a few seeds, badly preserved; (c) fragments of hazelnut (Corylus
avellana) pericarp; (d) a few small fragments of possible vegetative parenchyma
(soft storage tissue) which forms the major part of organs such as roots and tubers
(Hather 1993); and (e) miscellaneous plant material that could not be identified
further.
The results of the charcoal analysis are presented in Table 1. A summary of the
results can be seen in Table 2 and Fig. 3. In order to simplify presentation, identifications
have been grouped by the most probable taxa (that is, cf. oak/durmast oak
[Quercus robur/petraea] was classified as oak/durmast oak [Quercus robur/petraea]).
The fragment described as alder/birch (Alnus sp./Betula sp.) was not considered.
The data show that in the lower midden hazel is the most important taxon
(73.4% of the fragments identified), followed by oak (12.4%), alder (Alnus glutinosa,
6%), elm (Ulmus sp., 4%), and willow/aspen (Salix/Populus, 3%). Only one
fragment of birch (Betula sp.) and another belonging to the rose family (Rosaceae)
have been identified. Remains from the upper midden show that hazel continues to
be the most important taxon, but its proportion is reduced to approximately half of
the fragments identified (52.6%). In contrast, oak increases in relative importance
(30.7%) in the sample. Alder (9.6%), willow/aspen (5.2%), and birch (one fragment)
are the other taxa identified; in these cases the proportions are low, similar to
their frequency in the lower midden. No fragments of the rose family were identified
here (but only one had been recognized in the lower midden) and most importantly,
elm wood is no longer present. Layer 4 and the Layer 5/6 transition did not
yield statistically significant results since the number of fragments identified was
very low (18 and 25, respectively). The presence/absence of species is similar to
that in the midden deposits, however, in both cases the percentages are closer to the
lower midden, with proportions of hazel wood exceeding 70%.
Other carbonized plant remains besides wood charcoal are extremely scarce and
poorly preserved. There are only a few seeds (grass [Poaceae] and stitchwort
[Stellaria sp.]) and a few fragments of unidentified, possible parenchyma tissues.
The stitchwort seed was also identified at CMB I, along with the sporadic charred
seeds of sedge/knotgrass (Cyperaceae/Polygonaceae), bedstraw (Galium sp.),
cinquefoil (Potentilla sp.), and bramble/raspberry (Rubus fruticosus seu ideaus).
Except for the latter, these weeds – indicative of a humid environment – are difficult
to interpret in archaeological terms (Boardman 1993).
A few uncharred seeds were also present in some of the samples but these are
interpreted to be modern in origin. The small number of carbonized seeds and (possible)
parenchyma does not allow any paleoecological or paleoethnobotanical
interpretation. Fragments of hazelnut pericarp occurred commonly in the midden
samples. Much has been written about the role of hazelnuts as a past food resource, especially in the context of the European Mesolithic (Mason 1996), although hazelnuts
seem to have remained very popular until at least the Bronze Age at many sites
in Britain (Moffett et al. 1990).
Several explanations have been provided for the abundance of carbonized hazelnut
shells at the Mesolithic sites. It is often considered that they were roasted to
benefit storage or shelling, or to kill insects. Heating also releases oil and changes
oil structure, thereby improving flavor and making grinding easier. Hazelnuts may
also have been used as fuel. Boardman (1993) further notes that hazelnuts are one
of the few edible wild plants likely to be very productive under both fully wooded
and more open habitats. Most experts agree that these general explanations should
be supported by further ethnographic, taphonomic, and experimental research. 2.2 Animal Remains
To inform our discussion of the zooarchaeological remains from CMB II, we compared
our results for the major taxonomic groups with the number of identifiable animal
specimens (NISP) in water-sieved samples from CMB I, identified by Sheila
Hamilton-Dyer (1993) and Finbar McCormick (1993).
2.2.1 Bony Fish
This group comprised mainly the remains from both marine and anadromous/catadromous
fish (Table 3). The main characteristics of the identified taxa will be
reviewed in terms of their occurrences at CMB and the habitat types they represent.
Common eel (Anguilla anguilla) may attain a maximum length of 140 cm
(Campbell 1989:274). In contrast to CMB I, bones of this species occurred sporadically
at CMB II. The colorless elvers of eel move into brackish water areas and start
moving upstream to live in fresh water for several years. Some of them, however,
remain in river estuaries. The older individuals move downstream during their
spawning migration by the end of summer (Angel 1977: Figure 40). Present day
otter (Castor fiber) feces from Mull (Argyll) contained up to 7.4% eel remains
(Watt 1991:24, Table 7).
Remains from salmon (Salmo cf. salar) and trout (Salmo trutta; Salmonidae)
were found in significant numbers. Most of the remains originate from fairly large,
adult individuals. Smolts of salmon (Angel 1977: Figure 36) move down river to
the sea in May and June. They spend some time in estuaries where they acclimatize
to the salinity of sea. Most of these fishes migrate to the sea at a length of 10–19 cm
(Muus and Dahlstrøm 1977:76). The maximum adult length of these fishes is
1.5 m, although none of the bones recovered at CMB II belonged to such large
individuals. Trout (maximum adult length 1 m), a species with a similar life history,
is distinguished from salmon by its plumper body. Young trout migrate to the sea
when 15–25 cm long but they stay in the vicinity of the coast for 0.5–5 years (Muus
and Dahlstrøm 1977:78). Consequently, fragments not identifiable at the species
level may originate from either salmon or trout.
With the exception of cod (Gadus morrhua), species in the cod family (Gadidae)
prefer waters of high salinity. Their remains dominated the CMB II fish bone
assemblage, both in terms of NISP and weight. The young, especially, may be
caught along the shore. Species identification was limited to the few most diagnostic
skeletal elements. Of the known Mesolithic zooarchaeological assemblages
from Scotland, cod formed the majority of the identified fish remains at the east
coast site of Morton as well (McCormick and Buckland 1997:90). In later periods,
fishing in Scottish waters has increasingly concentrated on several species in the
cod family (Barrett et al. 1999:354).
At CMB II, poor cod (Trisopterus minutus), saithe (Pollachius virens), and
pollack (Pollachius pollachius) contributed the most identifiable bones to the gadid remains. Both small and large individuals were recognized among the latter.
While 19–23 cm long, poor cods are considered economically unimportant by
modern standards (Muus and Dahlstrøm 1977:106); saithe and pollack may reach
a maximum length of 130 cm, while they are 60–70 cm long in the fifth year.
Remains of small individuals from CMB II seem to correspond to the first year age
group in the bimodal size distributions obtained for this species by Mellars and
Wilkinson (1980:21). Whiting (Merlangius merlangus) can attain maximum
lengths of 40–50 cm (Muus and Dahlstrøm 1977:106). This species was far better
represented at CMB I.
Cuckoo wrasse (Labrus mixtus) is a fish whose length varies between 30 and
35 cm. It lives in the algal zone on rocky coasts (Muus and Dahlstrøm 1977:128),
usually in waters below 10 m (Campbell 1989: 288). Among the non-gadid species,
the contribution of labrids to prehistoric faunal assemblages seems to decrease
through time (Barrett et al. 1999: Figure 4). Gray gurnard (Eutrigla gurnardus) is
a bottom-dwelling species found in waters 10–150 m deep. It may reach a length
of 45 cm (Muus and Dahlstrøm 1977:162).
Bullheads or sea scorpions (Cottidae) are predatory, bottom-living fish with no
swim bladder. They do not move far from the area in which they have grown up
(Muus and Dahlstrøm 1977:12). While these usually small fish are of no known
commercial value today, their remains made up 11.3–12.4% of the fish bone recovered from otter feces in Mull (Watt 1991:24, Table 7). The remains of similar small
individuals were found in the CMB II material, a possible indication of animal
predation rather than human activity.
The family of right-eyed flatfish (Pleuronectidae) was represented by numerous
bones from dab (Limanda limanda), commonly occurring in coastal waters. The
length of this flatfish species rarely exceeds 40 cm (Muus and Dahlstrøm 1977:182).
While most adult flatfish occur at depths of 10–15 m, the young usually frequent
shallower coastal waters (Muus and Dahlstrøm 1977:184) and may even be caught
by hand. This is consistent with the observation that bones of this fish at CMB II
originate from small individuals.
High concentrations of small fish bones, especially when flattened and distorted,
showing signs of digestion (such as some salmon remains at CMB II), would alternatively
be characteristic of offal and feces from otter holts (Cerón-Carrasco
1992:3), daily hideouts of these animals.
2.2.2 Amphibians
Only sporadically occurring long bones of frogs/toads (Anura) were recognized in
the material. Remains from these small terrestrial animals, often considered commensal
at ancient settlements, most typically represent “taphonomic gain” resulting
from active intrusion or water transport (precipitation). In contrast to warmer
climates, where these animals grow large enough to be exploited for meat (Cooke
et al. 1996), it seems unlikely that bones of small frogs at CMB would have been
introduced by human consumption into the stratigraphy.
2.2.3 Birds
The exploitation of birds was of great importance in coastal adaptations throughout
the Mesolithic of northwestern Europe (Grigson 1989:60). In comparison with
mammals, usually numerous avian species are represented by relatively few bones,
a trend characteristic of bird remains owing to both their natural taxonomic diversity
and the greater degree of fusion between elements in the bird skeleton
(Bartosiewicz and Gál 2007). The bird taxa identified are compared to the results
from CMB I in Table 4. Bones of willow tit (Parus montanus), robin (Erithacus
rubecula), finch (Fringillidae), and other small perching birds may be considered
natural deposits at CMB II. These small birds indicate that the midden was located
in the woodland/littoral ecotone. Like amphibians, small birds identified at this site
are indicative of the natural habitat, rather than human activity.
Given the long tradition of seabird exploitation in the coastal areas of Scotland
(Serjeantson 1988), it is somewhat disappointing that larger birds are represented
only by one bone of a red-throated diver (Gavia stellata) and a cormorant
(Phalacrocorax carbo) each. The seven bones of puffin (Fratercula arctica) may
have even originated from burrowing individuals. At CMB I, remains of common or herring gull (Larus argentatus seu marinus), razorbill (Alca torda), and guillemot
(Uria aalge) form a group of findings that originate from birds most commonly
encountered in marine environments. White-tailed [sea] eagle (Haliaetus albicilla) is
more typical of coastal habitats than the golden eagle (Aquila chrysaetos), and its
eyries were usually on sea cliffs and pinnacles (Barnes 1975:83). The bird bone assemblages
from the two CMB sites may be seen as complementary to one another.
2.2.4 Mammals
Mammalian remains identified at CMB I by McCormick (1993) are compared to
the recent results in Tables 5 and 6. The greatest difference between the two faunal
assemblages is the overwhelming dominance of small rodents, especially bank vole
(Clethrionomys glareolus) and field vole (Microtus agrestis) remains, at CMB II.
Bones from these species must have been fewer at CMB I, although they were
quantified only using the loose term “dozens” in that report (see Table 5). Rodent
remains occur rather uniformly across all contexts.
Pigmy shrew (Sorex minutus) contributed the smallest bones to the CMB II
assemblage. Although common shrew (Sorex araneus) is known from CMB I
(Hamilton-Dyer and McCormick 1993), it was not recorded at Morton or sites on the island of Oronsay (Inner Hebrides). Although it is impossible to recover articulated
skeletons from sieve residues, given the excellent preservation of their bones at
CMB II, it is possible that these tiny animals found their way into the cracks and
cavities of the midden by entering into archaeological deposits in search of their
prey. The possibility of water transport must also be considered.
Of the numerous rodent remains deposited in all contexts, bank vole, field vole,
and water vole (Arvicola amphibius) could be identified to species on the basis of
tooth enamel patterns. Some specimens were assigned to the latter, largest species
on the basis of size. From an environmental point of view, it is significant that bank
voles inhabit mixed woodland habitats. This species is the only vole that climbs
bushes (Mitchell and Delap 1974:56). Field vole was also considered one of the
faunal indicators of a forested environment at the site of CMB I (Hamilton-Dyer
and McCormick 1993).
Woodland is best indicated by the presence of shrew and bank vole. Field and
water voles are typical of humid, bushy areas; this does not contradict the previous
conclusion. All these species may burrow near the soil surface, but are unlikely to
go deeper than 10 cm (Zsófia Kovács, personal communication 2008). Whether the
animals died at the site or their remains were washed in from above, their presence
is yet another indication that the immediate environment of the shell midden was
forested. Some bones of red squirrel (Sciurus cf. vulgaris) and pine marten (Martes
martes) at CMB I support the reconstruction of a woodland environment. The bones
of larger mammals, especially those of domesticates found in the upper midden at
CMB II, are the most likely to have been introduced by human activity (Table 6).
In contrast to rodent remains, two bones of common hare (Lepus timidus) in the
lower midden may originate from prey items of either animals or humans, and in
fact may have been imported by humans to the site. This is even more of a possibility
in the case of large mammals. Remains of sheep (Ovis aries) or, less likely, goat (Capra hircus), usually referred
to here by the subfamily name, Caprinae, were found in relatively large numbers in
the upper midden but only one such bone was found in the lower deposit. While the
latter, single occurrence may be considered accidental, the presence of domesticates
in the upper midden corresponds with the later chronological position of that deposit.
No cattle (Bos taurus) remains were found in either of these two layers at CMB II.
Wild boar (Sus cf. scrofa) is a mammal whose domestic form (Sus domesticus) is
often difficult to recognize from its skeletal remains. No suid bones were large enough
at this site to be unambiguously identified as those of wild pig, a game animal known
from Mesolithic deposits both at the site of Morton and even on the small island of
Oronsay (McCormick and Buckland 1997: Table 6.1). Although pig domestication is
not thought to have taken place before the Neolithic, several biological traits of this
species could have facilitated the development of a special relationship between wild
pigs and humans that preceded domestication in a classic sense (Bolomey 1973:48). Like dogs (Canis familiaris), these social animals were more likely to have scavenged
on human refuse than the ancestors of other, herbivorous domesticates.
In comparison with other ungulates, roe deer (Capreolus capreolus) is underrepresented
in the CMB II faunal assemblage. In addition to the identifiable remains
of this species, many of the 1,000+ small ungulate bone splinters probably belong
to roe deer. While some of these bones could not be distinguished from the remains
of sheep (hence, the term “small ruminant”), sheep could be present only if the
lower midden were post-Mesolithic in date. Roe deer remains occurred both on the
island of Oronsay and at Morton (McCormick and Buckland 1997: Table 6.1).
Together with wild pig, roe deer is considered to be an animal of deciduous woodland
with dense undergrowth or parkland habitats, although recently increasing
adaptation to open grassland has been recorded in Hungary (Bencze 1978:56). No
antler fragments could be identified as those of roe deer.
Red deer (Cervus elaphus) remains, including some antler fragments, occur sporadically
both in the upper and lower middens. Although red deer remains were found
in relatively small numbers, non-identifiable large ruminant bones probably also originate
from this animal. In comparison with small and adaptable roe deer (15–27 kg; van
den Brink 1968:157), large bodied red deer (95–160 kg in Scotland; van den Brink
1968:154) are more dependent on the cover provided by forested habitats.
When the number of taxa are plotted against the number of identifiable specimens
by vertebrate classes (fish, bird, and mammal), the subassemblages of various
sizes from the two CMB middens show the same trend in that they are in that they are comparable regardless of the differences in sample size. CMB II was particularly rich
in fish remains. The only outlier from this main trend (not taken into consideration
when calculating the regression line, Fig. 4), is the group of microvertebrate
remains. As mentioned before, the large number of these bones was counted in
terms of NISP only at CMB II, but the subassemblage was not very diverse, containing
only four identifiable taxa.
3 Discussion
Plant and animal remains differ radically in terms of their taphonomic histories,
including exploitation by humans as a cultural factor of biostratinomy. Prehistoric
plant remains recovered from CMB II have been preserved through charring. Wood
charcoal is the most frequent type of paleoethnobotanical material. Apart from the
possibility of natural forest fires, this special form of preservation also offers
evidence of human activity: the use of fire at the locus investigated, which includes
the selection and transport of firewood to the place of use.
Zooarchaeological remains may represent different forms of deposition. In order
of increasing complexity, faunal materials may originate from (Gautier 1987):
1. Intrusive animals (bones of actively burrowing rodents, shrews, puffins, etc.)
2. Carcasses originating from in situ death, water transport, or deposited by predators
(otter feces, owl pellets, gut contents of larger fish preyed upon by otters or
humans)
3. Human food refuse (bones showing butchering marks, burning, or marrow
extraction)
4. Debitage from craft activities (waste from in situ manufacturing, bones with
skinning marks)
Given the horizontal, coastal location of shell middens and their vertical positions
relative to prehistoric sea levels, the direct role of tidal activity in accumulating fish
remains should be considered. Many sites in central-west Scotland located below
15 m above present sea level were probably destroyed by wave erosion, or at least
affected by storm waves, during the Mid-Holocene marine transgression, which
culminated in the Oban area between 5500 and 5900 cal. bc (Bonsall and Sutherland
1992). As opposed to marine tidal activity, some bones representing terrestrial
microfauna (amphibians, insectivores, and rodents) may indeed have been washed
into the midden deposit by rainwater from above, a phenomenon frequently
observed in rockshelters and caves (e.g., Andrews 1990). This type of accumulation
is a characteristic source of microvertebrate remains.
Just as burning by humans contributed to the preservation of charred plant parts,
the vertebrate remains recovered from the middens also owe their survival, at least
partially, to human activity. In the highly acidic soils of the area, the preservation of
bone and antler simply would not have been possible without the accumulation of
shell middens. The calcareous organic matrix of predominantly limpet shell deposits (Russell in Connock et al. 1993:34; Bonsall et al. 1994) creates an alkaline environment,
buffering soil acidity and thereby promoting the preservation of bone.
3.1 Vegetation
Two of the main characteristics that explain the presence and relative importance of
any type of wood at an archaeological site are its relative abundance in the vicinity
and its quality as a fuel wood. The most abundant species and those that are considered
good fuel tend to be well represented. A relevant ethnobotanical study was
carried out among farmers in the Atlantic Basque Country, in areas where mixed
oak woodland is the main arboreal community. In Table 8, arboreal species identified
at CMB II were ranked according to the mean fuel quality value established
during that study (Zapata and Peña-Chocarro 2003).
The presence and relative abundance of the different fuel woods in the CMB II
deposits seem to indicate that hazel and oak wood were abundant around the site.
In all the samples, these two taxa account for more than 80% of the identified fragments.
Taphonomic problems aside, this would mean that there was a mixed-oak
woodland close to this site. According to Table 8, both hazel and oak are highly
valued fuel woods (oak scores 4 and hazel 3.8 on the 5-point scale of fuel quality
in domestic fires). Thus, hazel must have been a very important component of the
woodland around the site (in all samples, it constitutes over 50% of the fragments
identified). This is also supported by evidence from CMB I, where hazel nutshells
dominated the charred plant remains. Even if they were highly fragmented, significantly
overrepresenting the number of nuts involved, their presence is important in
itself (Boardman 1993).
The presence of elm charcoal in the lower midden and its absence from the
upper midden is interesting in light of the general decline in elm pollen values
recorded in pollen diagrams across NW Europe around the time of the Mesolithic–
Neolithic transition, 4150–3400 cal. bc (Parker et al. 2002). Could this indicate that
the lower midden at CMB II (layer 5) pre-dates the elm decline, which in the Oban
Table 8 Average scores of fuel quality for various species established in domestic fires (from
1 = very bad fuel to 5 = excellent fuel) according to modern farmers’ opinions (Zapata and Peña-
Chocarro 2003)
Species Fuel quality
Oak 4
Hazel 3.8
Willow 3
Birch 2.5
Elm 2.25
Alder 2
Aspen 1.4


area occurs ca. 3900 cal. bc (Davies 1997)? Since cultural selection of wood must
always be considered in charcoal analysis, this ecological conclusion needs to be
confirmed by direct radiocarbon dating of terrestrial organic matter (plant macro
remains or animal bone) from layer 5.
3.2 Fauna
Animal remains from the excavations at CMB II further complement the environmental
picture outlined by the charcoal analysis and also corroborate the previous
zooarchaeological study of CMB I by Hamilton-Dyer and McCormick (1993).
Their opinion that “much of the bone in the shell midden contexts can be accounted
for by natural factors” can be substantiated. The rodent and bird species identified
at this site reflect the proximity of wooded/bushy environments in the site’s immediate
proximity.
Some differences in diversity between the two faunal samples from CMB are
evidently related to assemblage size as has already been shown in Fig. 4 by the very
close (almost 99% determination) linear relationship between sample size and
sample richness. Poorly represented species are more likely to occur when more
specimens are available for study (Grayson 1984:137; see also Peres, this volume).
This is clearly the case with fish remains, where the number of identifiable bones
from CMB II is twice as great as from CMB I. Consequently, a slightly richer
inventory of species was recognized. Large numbers of salmon and cottid remains
at CMB II are especially conspicuous. The number of non-identifiable fish remains
is also greater at CMB II.
Almost the reverse of this situation, however, was observed in the case of birds.
Only remains of various (mostly non-identifiable) perching birds were found in the
samples from CMB II, while a fairly rich range of predominantly marine birds
came from the CMB I excavation. The different representation of fish and birds in
the two assemblages may indicate that there is more than a size-related difference
between the two assemblages. The greater numbers of non-identifiable fish and
vole bones from CMB II may result from finer recovery techniques applied at this
latter site; many of the bones were found by sieving through mesh sizes of 1 and
2 mm, respectively.
4 Summary and Conclusions
Both palaeoethnobotanical and zooarchaeological evidence available from the two
sites at CMB are primarily indicative of the environment. While charcoal was present
as a result of probably human-induced fire, it must have originated from locally
gathered wood. Many of the small terrestrial vertebrates (perching birds, rodents)
also seem to be indicators of a wooded natural environment. On the other hand, remains of hazelnut and hand-collected animal bones are indicative of human
subsistence activities related to the two shell middens.
It is too simplistic to assume that the proportions of tree taxa represented in
archaeological assemblages reflect their relative abundance in the local vegetation.
However, it is usually accepted that archaeological wood charcoal is an indicator of
at least some of the plant communities formerly growing in the site area and thus a
valuable source of data for reconstructing prehistoric vegetation and environments
(Smart and Hoffman 1988). Consideration should be given to: (1) taphonomic
questions; (2) cultural selection of wood; and (3) context-related variation within
the site.
Like plant remains, cultural deposits of animal remains tend to reflect culturally
idiosyncratic preferences, rather than the fauna of the local environment. However,
as far as the archaeological interpretation of the animal remains under discussion
here is concerned, rodent remains, rare bones from amphibians, and even some
small fish are unlikely to have been deposited by humans at CMB II. Sporadic long
bone fragments from frogs /toads (Anura) tend to appear only in the largest sieved
assemblages, thus being indicative of the effect of sample size on taxonomic
richness.
Although otter was identified only at CMB I, it is an important carnivore at midden
sites along the west coast of Scotland. The number of otter bones was second
only to those of seals at the “Obanian” site of Cnoc Coig, Oronsay, where these
animals were considered to have been hunted (Grigson and Mellars 1987:274).
In contrast to the other mammals previously discussed, otters could easily colonize
island habitats. Although this species thrives in fresh water, populations adapted to
marine environments have been regularly observed (Mitchell and Delap 1974:64).
Today, however, otters are rare around all the islands of the Inner Hebrides. These
avid predators of fish were treated as “vermin” in the recent past (Mercer 1974:46).
Otters feed on fish, such as wrasse, cod and other gadids, and flatfish, as well as on
various crustaceans (Matthews 1989:246).
The few pig and deer bones, on the other hand, directly reconfirm observations
by Hamilton-Dyer and McCormick (1993:34), concerning human exploitation of
the wild fauna. Although deer bones were most probably deposited by humans,
they are also characteristic of the wooded environment than the narrow littoral
zone. The CMB II assemblage contained only a few identifiable bones from marine
birds, a group which may have been targeted by Mesolithic hunters.
Complex relationships between the factors that determined the contents of the
two shell middens are summarized in Fig. 5. Special emphasis has been placed on
the importance of human activity in the preservation of zooarchaeological and
paleoethnobotanical remains in the middens, located in the ecotone between the
forested inland habitat and the littoral zone. Although humans inadvertently
contributed to the survival of the floral and faunal remains under discussion here,
many of the findings represent natural deposits, especially in the case of vertebrate
fauna. Studies of animal and plant remains from coastal shell middens have rarely
been given equal emphasis in archaeological research in western Scotland, and even
more rarely have attempts been made to integrate the two lines of evidence to aid in site interpretation. The results of zooarchaeological and paleoethnobotanical
research at Carding Mill Bay serve to emphasize that shell midden sites are the
result of activities that took place at the interface between land and sea, and while
they are an important repository of information on human exploitation of coastal
and marine resources, they also have the potential to inform us about the local terrestrial
environment and its use by humans.