Stable isotope composition of Helix ligata (Müller, 1774) from Late Pleistocene–Holocene archaeological record from Grotta della Serratura (Southern Italy): Palaeoclimatic implications

Global and Planetary Change 71 (2010) 249–257

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Global and Planetary Change

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Stable isotope composition of Helix ligata (Müller, 1774) from LatePleistocene–Holocene archaeological record from Grotta della Serratura(Southern Italy): Palaeoclimatic implications

André Carlo Colonese a,⁎, Giovanni Zanchetta b,c, Anthony E. Fallick d, Fabio Martini e,Giuseppe Manganelli f, Russell N. Drysdale g

a Department of Archaeology and Anthropology, Institución Milá y Fontanals, Spanish National Research Council (IMF-CSIC), GASA-UAB (CSIC-Associated Unit), Carrer de les Egipcíaques, 15,08001 Barcelona, Spainb Dipartimento di Scienze della Terra, University of Pisa, Via S. Maria, 53, 56126 Pisa, Italyc CNR-IGG, Via Moruzzi, 1, 56126 Pisa, Italyd Scottish Universities Environmental Research Centre, East Kilbride G75 0QF, Glasgow, United Kingdome Dipartimento di Scienze dell'Antichità “G. Pasquali,” University of Firenze, Piazza Brunelleschi 4, 50121 Firenze, Italyf Dipartimento di Scienze Ambientali, University of Siena, P.A. Mattioli 4, 53100 Siena, Italyg Environmental and Climate Change Group, The University of Newcastle, Callaghan NSW 2308, Australia

⁎ Corresponding author. Tel.: +34 93 442 3489; fax:E-mail addresses: [email protected] (A.C. Colone

(G. Zanchetta), [email protected] (A.E. Fallick), [email protected] (G. Manganelli), Russell.Drysdale@n(R.N. Drysdale).

0921-8181/$ – see front matter © 2009 Elsevier B.V. Aldoi:10.1016/j.gloplacha.2009.05.006

a b s t r a c t

Article history:Accepted 18 May 2009Available online 6 June 2009

Keywords:land snail shellsstable isotope compositionLate Pleistocene–Middle HolocenepalaeoclimateSouthern Italy

Carbon and oxygen isotope ratios were measured in fossil and recent shells of the land snail Helix ligata.Fossil shells were recovered from the archaeological excavations of Grotta della Serratura and recentspecimens collected adjacent to the cave. The record is discontinuous and spans from ca 14 to 7 ka cal BP.The oxygen isotope composition of the fossil shells suggests they were grown from environmental waters(e.g. precipitation) isotopically similar to the present during the recorded part of the Late Glacial. A notableexception is represented by a layer at ca 13.4 ka cal BP, with shells characterised by 18O-enriched values,suggesting drier conditions, with rainfall perhaps reduced by 25% compared to the present day. This layercould correspond in part with the GI-1b event of the Greenland ice-core records. The onset of the Holocenewas marked by a decrease of δ18O, suggesting an increase in humidity. Significantly lower δ18O values occurat ca 7.4 ka cal BP, in agreement with other stable isotope records, which suggests enhanced rainfall over theMediterranean region at that time.

© 2009 Elsevier B.V. All rights reserved.

1. Introduction

The impact of Quaternary climate changes on both the environ-ment and ancient societies is a matter of discussion in both thepalaeoclimate and archaeology communities (e.g. deMenocal, 2001;Staubwasser and Weiss, 2006). The most continuous and quantitativeinformation on these changes are usually not derived directly fromarchaeological successions, owing to their discontinuous nature andstrong disturbance by human activities. Instead, the relationshipbetween social and climatic changes is normally inferred fromarchives (e.g. lakes, speleothems, marine successions) sourced frombeyond excavation sites, although simple correlations betweenarchaeological records and such archives are not always straightfor-ward. Despite these potential limitations, many prehistoric suc-

+34 93 443 0071.se), [email protected]@unifi.it (F. Martini),ewcastle.edu.au

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cessions contain useful proxies from which to directly establishpalaeoenvironmental conditions at time of their formation. Theseinclude faunal remains, whose stable isotope composition areparticularly useful (e.g. Goodfriend and Ellis, 2000; Hedges et al.,2006). In particular, land snail shells are well represented in someprehistoric deposits (e.g. Evans, 1972; Colonese and Wilkens, 2005).

In several Late Glacial and Holocene prehistoric sites land snailshells are present both as natural accumulations and as dietary sourceremains (e.g. Lubell, 2004). Land snails move over short distances, andare very sensitive to environmental parameters, such as temperatureand moisture (e.g. Balakrishnan and Yapp, 2004 and referencestherein). Furthermore, their shells have a high-preservation potentialin neutral to alkaline deposits, so their stable isotope (oxygen andcarbon) composition of their shells is potentially an excellent sourcefor reconstructing local palaeoenvironment and palaeoclimate at timeof the shell growth.

Despite the fact that the origin and environmental significance of theland snail shell stable isotope composition isnot completely understood,previous studies have demonstrated that both oxygen and carbonisotope ratios can record terrestrial climatic changes (e.g., Yapp, 1979;

Fig. 1. (A) Map of Southern Italy and Sicily showing the archaeological site of Grottadella Serratura (1) and the previous studied site of Grotta del Romito (2). (B) Location ofGrotta della Serratura, including main relieves (Bulgheria Mountain 1225 m) and rivers(Lambro, Mingardo and Bussento) in the area.

Fig. 2. Monthly atmospheric temperature (T°C) and meteoric precipitation (mm) atMarina di Camerota for the year 2005 (data UCEA).

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Magaritz and Heller, 1980; Goodfriend et al., 1989; Goodfriend 1991,1992; Leng et al., 1998; Abell and Plug, 2000; Balakrishnan et al., 2005a,b; Colonese et al., 2007). Since archaeological excavations usuallycontain detailed stratigraphic successions, sometimes with accurateradiocarbon and/or luminescence chronologies, stable isotope analysison fossil land snail shells from these deposits can supply significantpalaeoclimatic and palaeoenvironmental clues. However, few studieshave considered the environmental significance of stable isotopes ofshells fromarchaeological successions in caves (e.g. Goodfriend and Ellis2000; Colonese et al., 2007). Compared to continental mollusc shells(e.g. Jones et al., 2002 for freshwater environment), the interpretation ofisotopic signals in land snails from archaeological successions in cavespresent additional complications. For instance, the origin and dynamicsof sedimentary records are affected by human disturbance, whichresults in variable temporal continuity of records in these environments(e.g. Woodwards and Goldberg, 2001 and references therein). Cavearchaeological deposits can preserve records at higher resolution whencompared to other terrestrial records containing land snail shells, such

as soils, but often these are not continuous and the potential forreworking is high.

A previous study performed at Grotta del Romito, southern Italy(Fig. 1), yielded rare evidence of the registration of an abrupt climateoscillation (the Older Dryas) in the oxygen isotopic composition ofland snail shells, encouraging further research (Colonese et al., 2007).This paper investigates the palaeoclimatic implications of oxygen andcarbon isotopic analysis of fossil shells from Grotta della Serratura, aprehistoric succession preserved within a coastal cave located ca50 km from Grotta del Romito (Fig. 1). The period under investigationspans the Late Glacial to Early–Middle Holocene. It also aims to furtherimproves our understanding of the environmental significance of thestable isotopic composition of land snail shells from CentralMediterranean regions in response to climate changes.

2. Regional and archaeological setting

Grotta della Serratura (39°59′N, 15°23′E) is located at ca 2 m a.s.l.at the foot of Monte Bulgheria, part of the Campanian–LucanianApennine chain, near the village ofMarina di Camerota (SW Italy). Thecoastal area consists mainly of carbonate promontories alternatingwith pocket beaches (Fig. 1), and is characterised by a typicalMediterranean climate with warm to hot dry summers and mildwet winters (Lionello et al., 2006). For the year 2005, mean monthlyair temperatures ranged from 13 °C (winter) to 28 °C (summer);monthly rainfall ranged from 14 mm to 113 mm, with an annualamount of 790 mm (Fig. 2); mean monthly soil moisture ranged from10% in summer to 93% in winter (Ufficio Centrale di Ecologia Agraria,www.ucea.it).

The main synoptic phenomena responsible for the more abundantrainfall during winter are generally associated with eastward-movingcyclonic depressions (e.g. Lionello et al., 2006), mainly controlled by theNorth Atlantic Oscillation (i.e., Hurrell, 1995; Brunetti et al., 2002). Onthe other hand, warm and dry conditions during summer are primarilyassociated with the northward shift of the Azores High Pressure (Bolle,2003). According to Bard et al. (2002), evaporation from theMediterranean Sea along the Tyrrhenian coast of the Italian peninsulaaccounts for ca 40% of the meteoric precipitation over this area. Localmeanannual oxygen isotopic compositionof rainfall is ca−5.5‰ (Leoneand Mussi, 2004). At the nearby meteorological station (e.g. Cosenza),Longinelli and Selmo(2003) found that seasonal isotopic oscillations areprimarily related to the amount of precipitation, possibly associatedwith different vapour sources (see Celle-Jeanton et al., 2001).

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Grotta della Serratura contains an important Late Pleistocene–Holocene stratigraphic succession, which has a prominent position inthe prehistoric framework of the Italian peninsula (Martini,1993). Thearchaeological excavation started in 1984 (Martini, 1993), and wasfocused on two different areas: #1 and #2 (Fig. 3B). Area #2 containsan Upper Palaeolithic succession cemented by percolation of carbo-nate-rich water, and was not considered in this study.

Palaeoenvironmental and cultural studies, including a detailed 14Cradiometric chronology, have already been published (Martini, 1993;Bertolini et al.,1996;Boscato,1997;Colonese andWilkens, 2005;Martiniet al., 2007) and are briefly summarised here for area #1, the subject ofthis study. In area #1, at more than 30 m from the entrance of the cave,the Late Glacial–Holocene succession consists of different sedimentarylevels (from 2 to 8), containing Upper Palaeolithic, Mesolithic andNeolithic remains (Fig. 3C). Two main sedimentary hiatuses have beenrecognised, dated to the Late Glacial (between 13,190±90 and 11,930±120 cal yr BP) and the onset of the Holocene (between 11,620±330 and7650±150 cal yr BP). According to the vertical and horizontaldistribution of archaeological remains, someof these levelswere furtherdistinct in layers (Letters) containing episodes of human occupation(Roman numbers) (Martini, 1993). For some of these episodes (i.e. 8A–8B; 8E–8F; 8FII–8G) 14C ages overlap or exhibit small inversions (takinginto account their appreciable age errors and the inherent complexity ofthe radiocarbon calibration curve for each interval), and suggest veryshort time intervals of deposition (Table 1). Some 14C ages show moresignificant divergences (i.e. 2V, 8D). This could be related to post-depositional contamination, such as the intrusion of organicmatter due

Fig. 3. (A) Grotta della Serratura, (B) location of archaeological excavation and provenance oarchaeological stratigraphy (from Martini, 1993, modified).

to biological (e.g. burrowingof insects and/or smallmammals, Schwarczand Rink, 2001) and/or anthropogenic processes (Martini, 1993).Nevertheless, the overall stratigraphic evidence, the substantial coher-ence of 14C ages (Table 1) and the succession of archaeological remainssuggests only minor post-depositional disturbances over the excavatedsuccession.

The succession of Grotta della Serratura has yielded numerousfaunal and artefact remains, among which land snail shells areprominent (Colonese and Wilkens, 2005). Their occurrence has beenrelated to human exploitation, as suggested for other prehistoric sitesof SW Italy and Mediterranean areas (e.g. Mussi et al., 1995; Lubell,2004), but this matter remains unresolved. Land snail shells weremore frequent in Late Glacial layers than those of the Holocene, withthe pulmonata Helix ligata exhibiting the highest frequency.

3. Materials and methods

This paper investigated shells of the land snail H. ligata (Gastro-poda, Pulmonata, Helicidae), a species endemic to Central–SouthernItaly which belongs to a group in need of taxonomic revision (Bodonet al., 1995). It is a poorly studied iteroparous species, inhabiting avariety of woodland habitats from 400 to 1000 m a.s.l. (Settepassi andVerdel, 1965). As with other large Helicids, it probably has a lifespan ofless than 5 years. H. ligata was selected for this study because it hasbeen widely documented in many prehistoric sites of Southern Italy(e.g. Mussi et al., 1995).

f land snail shells into the Grotta della Serratura (area #1) and (C) schematic profile of

Table 1Radiocarbon data performed on charcoal. 14C data are reported as conventional andcalibrated yr BP. Calibration was performed with CALPAL_A (advanced) (http://www.calpal.de; Weninger and Jöris, 2004).

Layer 14C yr BP 14C cal yr BP Lab. code Cultural epoch

2I 6480±100 7390±90 UtC-743 Middle Neolithic(Trichromic ware)2II 6350±120 7250±140 UtC-744

2III 6300±130 7200±160 UtC-7452IV 6380±90 7310±90 UtC-7462V 6030±130 6910±170 UtC-7472V 6590±120 7480±100 UtC-7483 6770±170 7650±150 UtC-7494 10,000±200 11,620±330 UtC-750 Mesolithic

(undifferentiated Epipalaeolithic)5 9790±170 11,220±320 UtC-7515 9720±60 11,060±140 Bnl-35686 9620±60 10,970±140 Bnl-35696 9770±140 11,140±250 UtC-752 Mesolithic (Sauveterrian)7 9870±70 11,330±100 Bnl-35707 10,230±130 11,980±310 UtC-7538A 10,000±130 11,570±230 UtC-754 Upper Palaeolithic

(Late Epigravettian)8B 10,270±140 12,060±320 UtC-7558B 10,220±60 11,930±120 Bnl-35718C 11,290±90 13,190±90 UtC-14188D 13,000±80 15,710±200 UtC-14198E 11,490±160 13,390±160 UtC-14208F 11,460±80 13,380±100 UtC-14638FII 12,100±100 14,160±250 Beta-632908FIII 11,880±120 13,780±140 Beta-632918G 12,060±90 14,040±190 Beta-63292

Table 2Oxygen and carbon isotopic composition, median, standard deviation (sd) and rangevalues of modern shells ofHelix ligata fromMarina di Camerota (Grotta della Serratura),Grotta del Romito (Colonese at al, 2007) and Latronico (Zanchetta et al., 2005).

δ18Os‰(V-PDB)

Median sd Δδ18

Os‰δ13Cs‰(V-PDB)

Median sd Δδ13

Cs‰

Marina di Camerota(this study)

−0.1 −12.90.1 −12.50.3 −13.5

−1.0 −13.7−0.2 −11.6−1.5 −0.2 0.7 1.8 −12.9 −12.9 0.8 2.1

Grotta del Romito(Colonese et al., 2007)

−0.4 −12.00.9 −13.30.1 −13.2

−0.9 −14.40.9 0.1 0.8 1.8 −13.0 −13.2 0.9 2.4

Latronico(Zanchetta et al., 2005)

−0.3 −8.5−0.2 −9.5−0.6 −0.3 0.2 0.4 −9.2 −9.2 0.5 1.0

252 A.C. Colonese et al. / Global and Planetary Change 71 (2010) 249–257

The analysed shells were derived from a number of the Late Glacialand Early–Middle Holocene archaeological layers of area #1 (Fig. 3B–C),relating to the distinct Late Epigravettian (Upper Palaeolithic),Mesolithic and Neolithic occupation events, spanning ca 14,000 to7300 cal yr BP (Table 1). Shells were collected during excavationsbetween 1984 and 2000, and were separated by sieving the bulksediment from each layer, such that there was no preferred spatialcollection over the layers. Preferably, shells from dated layers wereused in this study and for each of layers 3 to 9 entire shells wereanalysed, according to their abundance and preservation. Layerscontaining only fragmented shells (e.g. 8B, 8C, 8D) were not taken inconsideration because of the risk of reworking. All selected shellswere adult specimens (average size ca 26×26 mm), so their averageisotopic composition spans several years. Shells of living specimens(n=6) were collected at a short distance from the cave duringOctober 2005.

To check for evidence of recrystallization of the shells, modernmaterial and random samples for each archaeological layer wereanalysed using X-ray diffraction (XRD). The results indicate that therecent shells were entirely aragonite and the fossil ones had preservedinternal aragonite structures. The organic matter of the livingspecimens was removed by placing shells in a solution of 5% NaClOfor 48 h. Following this, complete archaeological and modern shellswere cleaned in 30% H2O2 for 24 h, placed in an ultrasonic bath, rinsedseveral times in deionised water, powdered and ashed in a low tem-perature oxygen plasma to remove organic contaminants (Zanchettaet al., 2005). Most of the samples were analysed at SUERC (EastKilbride, Scotland) with the AP2003 mass spectrometer equippedwith a separate acid injector system, after reaction with 105% H3PO4

under He atmosphere at 70 °C. A small number of shell powders wereanalysed using a GV Instruments GV2003 (GVI's successor to theAP2003) at the Advanced Mass Spectrometry Unit, The University ofNewcastle, Australia. Internal working standards of Carrara Marble(MAB1 — East Kilbride; NEW1 — Newcastle) were cross-checkedagainst the international standards NBS18 and NBS19.

Isotopic results (Tabs. 2 and 3) are reported using the conventionalδ‰-notation. Mean analytical reproducibility (±1σ) was±0.08‰and±0.15‰ for carbon and oxygen, respectively. The δ18O and δ13C

are reported relative to V-PDB, whereas the δ18O of waters are quotedto V-SMOW.

4. Results

4.1. Modern shells

Oxygen (δ18Os) and carbon (δ13Cs) isotopic values of shells of theliving specimens fromMarina di Camerota are reported in Table 2. Thetable also shows the δ18Os and δ13Cs values obtained in otherpopulations of H. ligata from Southern Italy (Zanchetta et al., 2005;Colonese et al., 2007). The δ18Os range from 0.3‰ to −1.5‰, with amedian value of −0.2±0.7‰. The δ18Os variability found(Δδ18Os=1.8‰), although large, is not surprising when comparedto δ18Os ranges in other modern Southern Italian specimens ofH. ligata and in other fossil and modern pulmonate species fromdifferent regions of the world (e.g. Lecolle, 1985; Goodfriend et al.,1989; Goodfriend and Ellis, 2002; Baldini et al., 2007; Yanes et al.,2008). Possible explanations for this large δ18Os variability includes:i) iteroparous species are pluriennal and the different age of thespecimens can produce isotopic differences due to intra-annual(seasonal) variability of climate conditions; ii) the conditions nec-essary for the post-hibernation and post-aestivation resumption ofactivity are species-dependent; however, individuals of the samepopulation may not become active at the same time (Cook, 2001);iii) individuals collected contained remains of organic tissue so it waspresumed they had died recently; however, the collected individualsare not necessarily contemporaneous. Therefore, both different intra-specific life spans and slightly different seasonal activity could bereasonably expected to explain δ18Os variability in contemporaneousland snail shells from the same community (Magaritz and Heller1983; Goodfriend et al., 1989).

Zanchetta et al. (2005) have recently obtained a relationshipbetween δ18Os of living land snail and local oxygen isotopiccomposition of rainfall (δ18Op) in the Italian peninsula:

δ18Op ¼ 0:65 δ18Os−5:44 ð1Þ

This relationship is valid for different species including H. ligata,since species-specific δ18Os offset is usually negligible (e.g. Lecolle,1985; Goodfriend et al., 1989; Zanchetta et al., 2005; Colonese et al.,2007). Applying Eq. (1) for the median δ18Os values of modern shellsfrom Marina di Camerota, a median δ18Op value of −5.5±0.4‰ isestimated. This value agrees well with measured δ18Op values(−5.5‰) in this area (Longinelli and Selmo, 2003; Leone and Mussi,2004).

Table 3Median, standard deviation (sd) and range of oxygen and carbon isotopic compositionof fossil land snail shells from Late Pleistocene–Holocene layers of Grotta dellaSerratura.

Layer Median δ18Os‰(V-PDB)

sd Δδ18Os‰ Median δ13Cs‰ (V-PDB) sd Δδ13Cs‰ N

2 −1.6 0.2 1.8 −9.0 1.8 4.9 77 −0.6 0.4 0.9 −8.7 0.5 1.3 68A −0.4 0.3 0.6 −8.4 0.6 1.2 38E 0.4 0.6 1.8 −9.0 0.3 1.0 98EII −0.1 0.5 1.5 −8.0 0.5 1.2 68EIII −0.1 0.5 1.2 −8.7 0.4 0.9 58F −0.5 0.5 1.4 −8.7 0.4 1.2 98FI −0.4 0.1 0.2 −9.2 0.1 0.2 38FII −0.2 0.5 1.2 −8.9 0.6 1.4 58FIII −0.3 0.1 0.2 −9.9 0.3 0.7 58G −0.1 0.8 2.5 −8.6 0.7 1.7 7

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The δ13Cs values of modern H. ligata range from −11.6‰ to−13.7‰, with a median value of −12.9±0.8‰ (Δδ13Cs=2.1‰),within the range found by Colonese et al. (2007) in another livingpopulation in Southern Italy (Table 2). According to the experimentsperformed by Stott (2002) and Metref et al. (2003) on Helix aspersa(Cornu aspersum in the recent literature) raised on controlledconditions, the δ13Cs of the living shells of Marina di Camerota iscompatible with a diet mainly composed of C3 plant material. Thisconclusion is valid only in the case that no particular carbon isotopicoffset exists between the species. However, the literature clearlyindicates that significant δ13Cs offsets between species are oftenpresent (e.g. Lecolle 1983, 1984), even if for Helix spp., which usuallyshow the most negative δ13Cs among species collected in the samelocalities, this offset should be negligible. Along with the effects

Fig. 4. δ18Os, δ13Cs and median values of archaeological land snail shells of Grotta della Serrrange of modern shells. Radiocarbon data reported as cal yr BP.

discussed previously for the oxygen isotope composition, the δ13Csvariability of 2.1‰ can additionally depend on different sources ofavailable food in the land snail activity sites (different proportion ofdecay material, which can be 13C-depleted) and/or different amountsof carbonate ingestion among different individuals (Goodfriend andEllis, 2000; Yanes et al., 2008). At a regional scale, distinct envi-ronmental conditions (e.g. temperature, moisture, atmospheric CO2

concentration) on carbon source can also be responsible for δ13Csdiscrepancies among modern populations (e.g. Goodfriend and Ellis,2000; Yanes et al., 2008). The 13C-enrichment of shells of Latronico(Zanchetta et al., 2005) compared to those of Marina di Camerota(Table 2), is possibly related to the changes in isotopic composition offood source, being Latronico located at higher altitude.

4.2. Late Glacial–Holocene shells

Late Glacial shells (layers 8E–8G) are, on average, generally18O-enriched compared to Early and Middle Holocene counterparts(layers 8A—7and2), (Table 3 andFig. 4). Except for layer 8E, LateGlacialshells, dated from 13,380 to 14,040 cal yr BP (layers 8EII–8G), did notexhibit a change in median δ18Os values, ranging from −0.4±0.1‰to −0.1±0.5‰. An 18O-enrichment is recorded in shells from layer8E (13,390 cal yr BP),which exhibits amedian δ18Os of 0.4±0.6‰. EarlyHolocene shells, dated in the narrow interval from11,330 to 11,570 cal yrBP (layers 7 and 8A), have median δ18Os of −0.6±0.4‰ and −0.4±0.3‰, respectively. Middle Holocene shells, dated 7310 cal yr BP(Layer 2), show the greatest apparent 18O-depletion (−1.6±0.6‰),providing amaximummedian δ18Os difference compared to Late Glacialshells of 2.1‰ and amedian 18O-depletion of 1.5‰ compared tomodernspecimens. ThemaximumandminimumΔδ18Oswere found in layer 8G(2.5‰) and layers 8FI and 8FIII (0.2‰) respectively.

atura and of modern shell from Marina di Camerota. Grey bands consist in the isotopic

254 A.C. Colonese et al. / Global and Planetary Change 71 (2010) 249–257

No significant trends are observed for δ13Cs values through LateGlacial–Holocene layers.Median δ13Cs values range from−8.0±0.5‰ to−9.5±0.3‰ across the entire stratigraphic succession (Δδ13Cc=1.5‰).Two shells from layer 2 are significantly 13C-depleted (i.e., −11.2‰ and−12.8‰), with δ13Cs values partially overlapping those of the livingpopulation. The maximum and minimumΔδ13Cs were found in layers 2(4.9‰) and 8FI (0.2‰) respectively.

The comparison of both δ18Os and δ13Cs values of Late Glacial–Holocene shells with those from modern counterparts showsinteresting features (Fig. 4). Late Glacial δ18Os values from layer 8Gto 8EII are in the range of values of the extant specimens. However,layer 8E (0.4±0.6‰) shows δ18Os values substantially higher thanthose measured in modern specimens.

As shown previously, except for some shells from layer 2, nosubstantial variations were recorded in δ13Cs values of prehistoricspecimens. Nevertheless, differences are apparent when data arecompared with the 13C/12C ratio of modern shells. Indeed, the carbonisotope composition of prehistoric shells is significantly 13C-enrichedwith respect to modern ones, providingmedian δ13Cs differences from3.4‰ (8FIII) to 4.9‰ (8EII).

5. Discussion

Jones et al. (2002) noted the influence of δ18Os variability offreshwater molluscs and their environmental interpretations. AtGrotta della Serratura, intra-stratum δ18Os variability of modern andarchaeological land snail shells increases up to 7 shells for layers(e.g. 8G=2.5‰), after which δ18Os variability decreases to valuesprovided by 6, 7 and 9 shells (from 1.4‰ to 1.8‰). It is interesting tonote that the higher δ18Os variability observed in layer 8G is caused bya single, notably 18O-enrriched (1.6‰), shell compared to the othersfrom this layer. This could suggest the intrusion of this shell, perhapsfrommore ancient layers not analysed in this work (Fig. 5). Although adefinitive figure cannot be inferred from Fig. 5, it seems reasonablethat ca 5–7 shells may provide the best compromise between δ18Osvariability and number of available shells from each layer. Conse-quently, environmental reconstructions can be achieved with higherconfidence only for those layers in which at least 6 shells wereanalysed. It is important to stress that in archaeological layers δ18Osvariability is due to “natural” intra-specific differences, as alreadydiscussed, and the variability introduced by the presence of progres-sive accumulation and mixing of snail populations of different age.Moreover, it is also possible that intra-specific isotopic variability is a

Fig. 5. Plot showing relations among δ18Os variability (Δδ18Os‰) and amount of shells.From 6 to 7 shells provide reliable δ18Os variability of land snails from analysed layers.

function of climate: in more stressed environments (e.g. arid) var-iability seems to be higher than in mild climate conditions (Zanchettaet al., 2005).

Given the relationship between δ18Os of modern land snails andδ18Op (Eq. 1, Zanchetta et al., 2005), it seems reasonable to interpretthe variations of the δ18Os of fossil specimens in terms of changes inthe past δ18O of meteoric precipitation. Modern variability in δ18Opalong the Tyrrhenian coast of the Italian peninsula is primarily relatedto variations of local temperature (~ +0.2‰/°C), and the amount ofprecipitation (~−0.2‰/100 mmmonth) (Bard et al., 2002; Longinelliand Selmo 2003); the latter may depend, at least in part, on isotopicdifferences between air masses of different origins (e.g., Celle-Jeantonet al., 2001). According to Bard et al. (2002), the above parametershave remained substantially constant during the last 175 kyr. There-fore, the oxygen isotopic composition of aragonitic shells should be, onaverage, minimally affected by temperature change because the frac-tionation factor between water and aragonite varies by ~ −0.2‰/°C(e.g. Patterson et al., 1993; Kim and O'Neil, 1997), counterbalancingthe effect on the δ18Op (~ +-0.2‰/°C). Therefore, the mechanismscontrolling δ18Os of land snails from Tyrrhenian side of Italy areexpected to be primarily: i) the amount of precipitation; ii) the effectof a change in the source of the precipitation and/or environmentalwater (e.g. dew, evaporation of local water, changes in sea isotopiccomposition); and iii) potential kinetic fractionation effects byevaporation of water from the land snail body surface (Balakrishnanand Yapp, 2004). The last point is linked to relative humidity, and canvary in concert with the previous two effects (i.e. increasing theaverage moisture will decrease the fractionation due to evaporationand mutatis mutandis).

Between ca 13,380 (layer 8F) and 14,040 (layer 8G) cal yr BP theclimatic conditions at the time of snail activity produced δ18O valuessimilar to the present, suggesting environmental water similar tomodern conditions. An analogous conclusion has been inferred fromGrotta del Romito (Fig. 1, Colonese et al., 2007) for the part of the LateGlacial investigated. The significant 18O-enrichment shown by layer8E at Grotta della Serratura suggests a substantial increase of the δ18Oof environmental water at 13,390 cal yr BP. Since no isotopic anomalyhas been observed in layers chronologically close to 8E (e.g. 8EII, 8EIIIand 8F), higher δ18Os at 8E could be indicative of a sudden and shortclimatic oscillation recorded by shells at ca 13,390 cal yr BP. UsingEq. (1) for calculating the isotopic composition of palaeorainfall andthe rate value of −0.2‰/100 mm month for the amount effect (Bardet al., 2002), it is possible to calculate for layer 8E an annual reductionin rainfall of ca 200 mm, ca 25% less than the present amount ofprecipitation. Between 11,330 (layer 7) and 11,570 (layer 8A) cal yr BPshell 18O-depletions suggest a modest enhancement of rainfall at thevery base of the Holocene, compared to the average of the Late Glacial.A substantial increase of rainfall (ca 500mm) can be calculated for theMiddle Holocene, at ca 7310 cal yr BP, owing to the significant shell18O-depletion in layer 2.

As discussed for the Late Glacial at Grotta del Romito (Coloneseet al., 2007), major shifts in δ18Os can also involve changes in sourcesand/or trajectory of air masses over this region. Since MediterraneanSeawater vapour strongly influences δ18Op along the Tyrrhenian coastof the Italian peninsula (Gat et al., 2003; Longinelli and Selmo, 2003),changes in oceanic and Mediterranean δ18O seawater betweenthe Late Pleistocene–Holocene could have produced differences inoxygen isotopic composition in land snail shells. For instance, vapourderived from Mediterranean Sea during the Late Glacial could havebeen 18O-enriched when sea level was lower and the Mediterraneanwas characterised by higher salinity and higher δ18O (Kallel et al.,1997; Eimes et al., 2000; Paul et al., 2001). From the Last GlacialMaximum to the present full interglacial conditions, the oxygenisotope composition has changed by ca 1‰ and in the MediterraneanSea an additional ca 0.2‰ must be added for evaporation (Paul et al.,2001 and references therein). These changes can account only for a

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part of the Middle Holocene shift in layer 2, and cannot explain theoxygen isotopic values of the living land snails. Moreover, if thiseffect was dominant, we should also expect an important change(i.e. progressive 18O-depleted values) during the Late Glacial owing tothe rapid deglaciation and sea-level rise (e.g. Lambeck and Chappell,2001) during this period. But this is not evident in Grotta dellaSerratura nor in Grotta del Romito. Therefore, we are inclined tobelieve that the effect of changes in seawater isotopic compositionwas exceeded by other effects on meteoric precipitation, such as theamount effect.

Overall, the δ18Os record is in broad agreement with otherpalaeoclimatic records from the region in indicating a generallyenhanced meteoric precipitation from the Late Glacial to the Early–Middle Holocene in Central–Southern Italy (e.g., Follieri et al., 1988,1989, 1997; Huntley et al., 1999; Sadori and Narcisi, 2001; Zanchettaet al., 2007a,b). Unfortunately, the absence of cave deposits directlyrelated to the intervals spanning from ca 12,000 to 13,000 and ca 8000to 11,000 cal yr BP make it impossible to use the shell isotopiccomposition to resolve the detail of this transition.

Interestingly, layer 8E is chronologically close to layer C2–C4(12,980–13,160 cal yr BP) at Grotta del Romito (Colonese et al., 2007),with shells slightly 18O-enriched. However, it is difficult to establish ifthis isotopic shift is associated with local factors or to a large-scaleclimatic change. Taking into account age-model uncertainty, thetiming of this event is close to an abrupt climatic oscillation recordedin deep-sea and lake cores of the Central Mediterranean (e.g. Asioliet al., 1999; Huntley et al., 1999; Sprovieri et al., 2003; Magny et al.,2006; Drescher-Scheneider et al., 2007), and correlated by someauthors to the GI-1b event of Greenland ice cores (Björk et al., 1998).Whether these events are genuinely representing the same climaticdeterioration and can be correlated with GI-1b is not easy to ascertain.On the other hand, the significant decrease of δ18Os at 7310 cal yr BPcan be chronologically related to the late humid period inferred bypollen (e.g. Rossignol-Strick, 1999; Sadori and Narcisi, 2001) andstable isotope records overMediterranean (Bar-Matthews et al., 2000;Zanchetta et al., 2007a,b) synchronous with the formation of SapropelS1b in western Mediterranean Sea (e.g. Ariztegui et al., 2000; Arzet al., 2003). A significant 18O-depletion in Early–Middle Holoceneland snail shells have been also detected in the Eastern Mediterranean(Israel) and has been interpreted as changes in trajectories of air massover this region (Goodfriend, 1991).

Cultural evidence of human adaptation to environmental condi-tions across the Late Glacial–Middle Holocene at Grotta della Serraturasupports the palaeoclimatic reconstruction provided by land snailshell isotopic composition. This is particularly evident through varia-tions of large faunal remains over these intervals (Martini, 1993;Martini et al., 2007). For instance, during the Late Glacial occupation ofthe cave the most hunted species was the red deer (Cervus elaphus),followed by wild boar (Sus scrofa) and roe deer (Capreolus capreolus).Species related to open (i.e. Bos primigenius, Equus hydruntinus) andsteep slope environments, (i.e. Capra ibex, Rupicapra sp.) were alsoexploited at that time, but with lower frequency. The exploited faunalassemblage changes at the onset of the Holocene, with a prevalentexploitation of the wild boar, followed by roe deer and red deer. Giventhe subsistence system of the prehistoric groups in this region(Martini et al., 2007), such a faunal trend is probably related tochanges in faunal-type availability between the Late Pleistocene andMiddle Holocene that could have been driven by the progressiveexpansion of closed woodland areas owing to the increase ofatmospheric moisture (Sala, 1983).

The carbon isotope composition of land snail shells is believed to berelated to the isotopic composition of the ingested food (Goodfriend andEllis, 2000; Goodfriend and Ellis, 2002; Stott, 2002; Metref et al., 2003;Romaniello et al., 2008; Yanes et al., 2008), which can be broadlyindicative of local prevailing vegetation type (e.g. C3/C4 ratio) and itsisotopic composition (e.g. Goodfriend et al., 1989; Goodfriend and Ellis,

2002; Baldini et al., 2007; Yanes et al., 2008). The latter also depends onenvironmental parameters like water stress or concentration of atmo-spheric CO2 (e.g. Farquhar and Richards 1984). If, as discussedpreviously, living snails have a prevalent diet composed by C3 plants,Late Glacial and Middle Holocene counterparts may have had acomponent of C4 in their diet, a fact that could be reasonable for theLate Glacial but poorly sustainable for the Holocene (Korner et al., 1991;McDermott et al., 1999). It is interesting to note that in the companionstudy performed at Grotta del Romito (Fig. 1), Colonese et al. (2007)found similar differences in the δ13C composition of Late Glacial landsnail shells compared to modern counterparts (ca 3‰–4‰). Part of thisdifference could be associated with the burning of fossil fuels due toindustrialisation, which has released isotopically light carbon into theatmosphere, such that the δ13C value of atmospheric CO2 has declined byca 1.5‰ since industrialisation (e.g. Friedli et al., 1986). However, thiscannot completely account for the significant carbon isotope differencebetween living and fossil snail. Although Colonese et al. (2007) did notrule out the possibility of the presence of C4 plant in the Late Glacialvegetation, they noted that the 13C-enriched values during Late Glacialcould also be consistent with the effect of low CO2 partial pressure inatmosphere at that time (Indermuhle et al., 1999; Monnin et al., 2001),whichmay have produced a general increase in the δ13C values of plants(Farquhar and Richards, 1984), propagating through the food chain toland snail and other organisms. This is substantially consistent with thedata on organic matter and bone collagen δ13C records (e.g. Krishana-murthy and Epstein, 1990; Stevens and Hedges, 2004). However, thisinterpretation is unlikely to explain the δ13C values of the onset of theHoloceneand layer 2. It is possible that the combinedeffect of changes ofC3/C4 during Late Glacial–Holocene, humidity conditions and CO2

concentration may have produced the substantially invariant δ13Csvalues over the record, and the substantially higher values than livingspecimens. It is alsoknownthat shellsmay ingest a significant amountoflimestone for secreting their shells (e.g. Romaniello et al., 2008), butthere is no conclusive evidence that this amount can change as afunction of climate. However, the role of each of these variables is stilldifficult to quantify, and more successions containing the whole Glacialto Holocene transition and more complete Holocene successions areneeded.

6. Conclusion

Land snail shells are often recorded in archaeological deposits ofdifferent age and cultural settings along the Mediterranean basin.Therefore, they can be considered a useful source of palaeoclimaticand palaeoenvironmental information in which to frame humanbehaviours and cultural dynamics. Although discontinuous, theoxygen isotopic record of land snails from Grotta della Serratura hasgiven interesting indications of the hydrological changes occurringduring the Late Glacial and Holocene transition. The driest cli-matic conditions were inferred in layer 8E at ca 13,390 cal yr BP.Chronologically, this layer may correspond to a regional climaticevent related to GI-1b in Greenland ice cores. On the other hand, the18O-depletion at the onset of the Holocene is consistent with anincrease in atmospheric precipitation through the Early–MiddleHolocene, in which 18O-depleted shells at ca 7310 cal yr BP is asso-ciated to the humid period prevalent at the time of deposition ofsapropel S1 in western Mediterranean Sea.

The δ13Cs record did not show significant variation between theLate Glacial and the Holocene, but the values are consistently higherthan those of shells of living land snails. This is probably the combinedeffect of lower CO2 atmospheric concentration over the LatePleistocene and the Middle Holocene, different vegetation type andenvironmental stress affecting the carbon isotope composition of theingested food. However, we have to stress that the interpretation ofcarbon isotopes in land snail shells is still a problem, at least in thesuccessions studied so far in southern Italy.

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Acknowledgements

This work has been partially funded by the University of Pisa(Zanchetta, Fondi di Ateneo). We thank A. Tait, J. Dougans andT. Donnelly for analytical support for the SUERC stable isotopemeasurements and T. Smith for analytical support for the University ofNewcastle stable isotope measurements. SUERC is funded by aconsortium of Scottish Universities and NERC. We also thank DomenicoLo Vetro (Museo e Istituto Fiorentino di Preistoria “P. Graziosi”) forassistance. The comments and suggestions of two anonymous reviewerssignificantly improved the quality of the manuscript.

References

Abell, P.I., Plug, I., 2000. The Pleistocene/Holocene transition in South Africa: evidencefor the Younger Dryas event. Global Planetary Change 26, 173–179.

Ariztegui, D., Asioli, A., Lowe, J.J., Trincardi, F., Vigliotti, L., Tamburini, F., Chondrogianni, C.,Accorsi, C.A., Bandini Mazzanti, M., Mercuri, M.A., Van der Kaars, S., McKenzie, J.A.,Oldfield, F., 2000. Paleoclimate and the formation of sapropel S1: inferences from LateQuaternary lacustrine and marine sequences in the central Mediterranean region.Palaeogeography, Palaeoclimatology, Palaeoecology 158, 215–240.

Arz, H.W., Lamy, F., Pätzold, J., Müller, P.J., Prins, M., 2003. Mediterranean moisturesource for an early-Holocene humid period in the Northern Red Sea. Science 300,118–121.

Asioli, A., Trincardi, F., Lowe, J.J., Oldfield, F., 1999. Short-term climate changes duringthe Last Glacial–Holocene transition: comparison between Mediterranean recordsand the GRIP event stratigraphy. Journal of Quaternary Science 14, 373–381.

Balakrishnan, M., Yapp, C.J., 2004. The flux balance model for the oxygen and carbonisotope compositions of land snail shells. Geochimica et Cosmochimica Acta 68,2007–2024.

Balakrishnan, M., Yapp, C.J., Meltzer, D.J., Theler, J.L., 2005a. Paleoenvironmental of theFolsom archeological site, New Mexico, USA, approximately 10,500 14C yr B.P. asinferred from stable isotope composition of fossil land snail shells. QuaternaryResearch 63, 31–44.

Balakrishnan, M., Yapp, C.J., Theler, J.L., Carter, B.J., Wyckoff, D.G., 2005b. Environmentalsignificance of 13C/12C and 18O/16O ratios of modern land-snail shells from southerngreat plains of North America. Quaternary Research 63, 15–30.

Baldini, L.M., Walker, S.E., Railsback, B., Baldini, J.U.L., Crowe, D.E., 2007. Isotopic ecologyof the modern land snail Cerion, San Salvador, Bahamas: preliminary advancestowards establishing a low latitude island palaeoenvironmental proxy. Palaios 22,147–187.

Bard, E., Delaygue, G., Rostek, F., Antonioli, F., Silenzi, S., Schrag, D., 2002. Hydrologicalconditions over the western Mediterannean basin during the deposition of the coldSapropel 6 (ca. 175 kyr BP). Earth and Planetary Science Letters 202, 481–494.

Bar-Matthews, M., Aylon, A., Kaufman, A., 2000. Timing and hydrological conditions ofSapropel events in the Eastern Mediterranean, as evident from speleothems, Soreqcave, Israel. Chemical Geology 169, 145–156.

Bertolini, M., Fedozzi, S., Martini, F., Sala, B., 1996. Late Glacial and Holocene climaticoscillations inferred from the variations in the micromammal associations at Grottadella Serratura (Marina di Camerota, Salerno, S. Italy). Il Quaternario 9, 561–566.

Björk, S., Walker, M.J.C., Cwynar, L.C., Johnsen, S., Knudsen, K.-L., Lowe, J.J., Wohlfarth, B.,INTIMATE-Members, 1998. An event stratigraphy for the Last Termination in theNorth Atlantic region based on the Greenland ice-core record: a proposal by theINTIMATE group. Journal of Quaternary Science 13, 283–292.

Bodon, M., Favilli, L., Giusti, F., Manganelli, G., 1995. Gastropoda Polmonata. In: Minelli, A.,Ruffo, S., La Posta, S. (Eds.), Checklist delle specie della fauna italiana. Calderoni, Siena,pp. 1–60.

Bolle, H.J., 2003. Mediterranean climate. Variability and Trends. Springer, Berlin.Boscato, P., 1997. Associazioni faunistiche e adattamenti al territorio durante il

Tardoglaciale lungo la costa del Cilento (Salerno). Convegno Nazionale di Arche-ozoologia, Asti, Forli, Italy, pp. 167–173.

Brunetti, M., Maugeri, M., Nanni, T., 2002. Atmospheric circulation and precipitation inItaly for the last 50 years. International Journal of Climatology 22, 1455–1471.

Celle-Jeanton, H., Travi, Y., Blavoux, B., 2001. Isotopic typology of the precipitation in theWestern Mediterranean region at three different time scales. Geophysical ResearchLetters 28, 1215–1218.

Colonese, A.C., Wilkens, B., 2005. The malacofauna of the Upper Palaeolithic levels atGrotta della Serratura (Salerno, Southern Italy). In: Bar-Yosef, D. (Ed.), PreliminaryData. In: Archaeomalacology: Molluscs in Former Environments of HumanBehaviour. Oxbow Books, Oxford, pp. 63–70.

Colonese, A.C., Zanchetta, G., Fallick, A.E., Martini, F., Manganelli, G., Lo Vetro, D., 2007.Stable isotope composition of Late Glacial land snail shells from Grotta del Romito(Southern Italy): palaeoclimatic implications. Palaeogeography, Palaeoclimatology,Palaeoecology 254, 550–560.

Cook, A., 2001. Behavioural ecology: on doing the right thing, in the right place at theright time. In: Barker, G.M. (Ed.), The Biology of Terrestrial Molluscs. InCABInternational, Wallingford, pp. 447–487.

deMenocal, P.B., 2001. Cultural responses to climate change during the Late Holocene.Science 292, 667–673.

Drescher-Schneider, R., de Beaulieu, J.L., Magny, M., Walter-Simonnet, A.V., Bossuet, G.,Millet, L., Brugiapaglia, E., Drescher, A., 2007. Vegetation history, climate and human

impact over the last 15,000 years at Lago dell'Accesa (Tuscany, central Italy).Vegetation History and Archaeobotany 16, 279–299.

Eimes, K.-C., Struck, U., Schulz, H.-M., Rosemberg, R., Bernasconi, S., Erlenkeuser, H.,Sakamoto, T., Martinez-Ruiz, F., 2000. Temperature and salinity variations ofMediterranean Sea surface waters over the last 16,000 years from records ofplanktonic stable oxygen isotopes and alkenone unsaturation ratios. Palaeogeo-graphy, Palaeoclimatology, Palaeoecology 158, 259–280.

Evans, J.G., 1972. Land Snails in Archaeology. Seminar Press, London.Farquhar, G.D., Richards, R.A., 1984. Isotopic composition of plant carbon correlates with

water-use efficiency of wheat genotypes. Australian Journal of Plant Physiology 11,539–552.

Follieri, M., Magri, D., Sadori, L., 1988. 250,000-year pollen record from Valle diCastiglione (Roma). Pollen et Spores 30, 329–356.

Follieri, M., Magri, D., Sadori, L., 1989. Pollen stratigraphical synthesis from Valle diCastiglione (Roma). Quaternary International 3–4, 81–84.

Follieri, M., Giardini, M., Magri, D., Sadori, L., 1997. Palynostratigraphy of the last glacialperiod in the volcanic region of Central Italy. Quaternary International 47–48, 3–20.

Friedli, H., Lötscher, H., Oeschger, H., Siegenthaler, U., Stauffer, B., 1986. Ice core record ofthe 13C/12C ratio of atmospheric CO2 in the past centuries. Nature 324, 237–238.

Gat, J.R., Klein, B., Kushnir, Y., Roether, E., Wernli, H., Yam, R., Shemesh, A., 2003. Isotopecomposition over the Mediterranean Sea: an index for the air–sea interactionpattern. Tellus B 55, 953–965.

Goodfriend, G.A.,1991. Holocene trends in 18O in land snail shells from theNegevDesert andtheir implications for changes in rainfall source areas.QuaternaryResearch35, 417–426.

Goodfriend, G.A., 1992. The use of land snail shells in paleoenvironmental reconstruc-tion. Quaternary Science Reviews 11, 665–685.

Goodfriend, G.A., Ellis, G.L., 2000. Stable carbon isotope record of middle to lateHolocene climate changes from land snail shells at Hinds Cave, Texas. QuaternaryInternational 67, 47–60.

Goodfriend, G.A., Ellis, G.L., 2002. Stable carbon and oxygen isotopic variations inmodern Rabdotus land snail shells in the southern Great Plains, USA, and theirrelation to environment. Geochimica et Cosmochimica Acta 66, 1987–2002.

Goodfriend, G.A., Magaritz, M., Gat, J.R., 1989. Stable isotope composition of land snailbody water and its relation to environmental water and shell carbonate.Geochimica et Cosmochimica Acta 53, 3215–3221.

Hedges, R.E.M., Stevens, R.E., Koch, P.L., 2006. Isotopes in bones and teeth. In: Leng, M.J.(Ed.), Isotopes in Palaeoenvironmental Research. In: Developments in Paleoenvir-onmental Research Series, vol. 10. Springer, The Netherlands, pp. 117–146.

Huntley, B., Watts, W.A., Allen, J.R.M., Zolitschka, B., 1999. Palaeoclimate, chronologyand vegetation history of the Weichselian Lateglacial: comparative analysis of datafrom three cores at Lago Grande di Monticchio, southern Italy. Quaternary ScienceReviews 18, 945–960.

Hurrell, J.W., 1995. Decadal trends in the North Atlantic Oscillation and relationships toregional temperature and precipitation. Science 269, 676–679.

Indermühle, A., Stocker, T.F., Joos, F., Fisher,H., Smith,H.J.,Wahlen,M., Deck, B.,Mastroianni,D., Tschumi, J., Blunier, T., Mayer, R., Stauffer, B.,1999. Holocene carbon-cycle dynamicsbased on CO2 trapped in ice at Taylor Dome, Antartica. Nature 398, 121–126.

Jones, M.D., Leng, M.J., Eastwood, W.J., Keen, D.H., Turney, C.S.M., 2002. Interpretingstable-isotope records from freshwater snail-shell carbonate: a Holocene casestudy from Lake Gölhisar, Turkey. The Holocene 12, 629–634.

Kallel, N., Paterne, M., Labeyrie, L., Duplessy, J.-C., Arnold, M., 1997. Temperature andsalinity records of the Tyrrhenia Sea during the last 18,000 years. Palaeogeography,Palaeoclimatology, Palaeoecology 135, 97–108.

Kim, S.T., O'Neil, J.R., 1997. Equilibrium and nonequilibrium oxygen isotope effect insynthetic carbonates. Geochimica et Cosmochimica Acta 61, 3461–3475.

Körner, Ch., Farquhar, G.D., Wong, S.C., 1991. Carbon isotope discrimination by plantsfollows latitudinal and altitudinal trends. Oecologia 88, 30–40.

Krishanamurthy, R.V., Epstein, S., 1990. Glacial–interglacial excursion in the concentrationof atmospheric CO2: effect in the 13C/12C ratio inwood cellulose. Tellus B 42, 423–434.

Lambeck, K., Chappell, J., 2001. Sea level change through the last glacial cycle. Science292, 679–685.

Lécolle, P., 1983. Relation entre les teneurs en 18O et 13C des test de Gastéropodesterrestres et le climat océanic et alpin. Comptes Rendus de l'Académie des Sciences297, 863–866 II.

Lécolle, P., 1984. Influence de l'altitude en climat méditerranéen sur les teneurs enoxygéne-18 et carbone-13 des coquilles de gastéropodes terrestres. ComptesRendus de l'Académie des Sciences 298, 211–214 II.

Lécolle, P., 1985. The oxygen isotope composition of landsnail shells as a climaticindicator: applications to hydrogeology and paleoclimatology. Chemical Geology(Isotope Geoscience Section) 58, 157–181.

Leng, M.J., Heaton, T.H.E., Lamb, H.F., Naggs, F., 1998. Carbon and oxygen isotope variationswithin the shell of an African land snail (Limicolaria kambeul chudeaui Germani): ahigh-resolution record of climate seasonality. The Holocene 4, 407–412 8.

Leone, G., Mussi, M., 2004. Environmental isotopes and well waters and underseasulphurous outflows at Capo Palinuro, Salerno. Journal of Technical and Environ-mental Geology 3, 35–48.

Lionello, P., Malanotte-Rizzoli, P., Boscolo, R., 2006. Mediterranean Climate Variability,vol. 4. Elsevier, The Netherlands.

Longinelli, A., Selmo, E., 2003. Isotopic composition of precipitation in Italy: a firstoverall map. Journal of Hydrology 270, 75–88.

Lubell, D., 2004. Prehistoric edible land snails in the circum-Mediterranean: thearchaeological evidence. In: Brugal, J.J., Desse, J. (Eds.), Petits animaux et SociétésHumaines, Du Complément alimentaire aux ressources utilitaires, XXIV rencontresinternationales d'archéologie et d'histoire d'Antibes, Antibes, France, pp. 41–62.

Magaritz, M., Heller, J., 1980. A desert migration indicator—oxygen isotopic composition ofland snail shells. Palaeogeography, Palaeoclimatology, Palaeoecology 32, 153–162.

257A.C. Colonese et al. / Global and Planetary Change 71 (2010) 249–257

Magaritz, M., Heller, J., 1983. Annual cycle of 18O/16O and 13C/12C isotope ratios in landsnail shells. Isotope Geoscience 1, 243–255.

Magny, M., de Beaulieu, J.L., Drescher-Schneider, R., Vanniere, B., Walter-Simonnet, A.V.,Millet, L., Bossuet, G., Peyron, O., 2006. Climatic oscillations in central Italy duringthe Last Glacial–Holocene transition: the record from Lake Accesa. Journal ofQuaternary Science 21, 311–320.

Martini, F., 1993. Grotta della Serratura a Marina di Camerota. Culture e ambienti deicomplessi olocenici. Firenze, Italy.

Martini, F., Cilli, C., Colonese, A.C., Di Giuseppe, Z., Ghinassi, M., Govoni, L., Lo Vetro, D.,Martini, G., Ricciardi, S., 2007. L'Epigravettiano tra 15.000 e 10.000 anni da oggi nelbasso versante tirrenico: casi studio dell'area calabro-campana. In: Martini, F. (Ed.),L'Italia tra 15.000 e 10.000 anni fa. Cosmopolitismo e regionalità nel Tardoglaciale,Millenni, Studi di Archeologia Preistorica, 5, Firenze, pp: 157–208.

McDermott, F., Frisia, S., Huang, Y., Longinelli, A., Spiro, B., Heaton, T.H.E., Hawkesworth, C.J.,Borsato, A., Keppens, E., Fairchild, I.J., van der Borg, K., Verheyden, S., Selmo, E., 1999.Holocene climate variability in Europe: evidence from δ18O, textural and extension-rate variations in three speleothems. Quaternary Science Review 18, 1021–1038.

Metref, S., Rousseau, D.-D., Bentaleb, I., Labonne, M., Vianey-Liaud, M., 2003. Study ofthe diet effect on δ13C of shell carbonate of the land snail Helix aspersa inexperimental conditions. Earth and Planetary Science Letters 211, 381–393.

Monnin, E., Indermühle, A., Dällenbach, A., Flückiger, J., Stauffer, B., Stocker, T.F.,Raynaud, D., Barnola, J.-M., 2001. Atmospheric CO2 Concentrations over the LastGlacial Termination. Science 291, 112–114.

Mussi, M., Lubell, D., Arnoldus-Huyzendveld, A., Agostini, S., Coubray, S., 1995. Holoceneland snail exploitation in the highlands of Central Italy and Eastern Algeria: acomparison. Préhistoire Européenne 7, 169–189.

Patterson, W.P., Smith, G.R., Lohmann, K.C., 1993. Continental paleothermometry andseasonality using the isotopic composition of aragonite otoliths of freshwaterfishes. In: Swart, P.K., Lohman, K.C., McKenzie, J., Savin, S. (Eds.), Climatic Change inContinental Isotopic Records: Geophysical Monograph, vol. 78, pp. 191–202.

Paul, H.A., Bernasconi, S.M., Schmid, D.W., McKenzie, J.A., 2001. Oxygen isotopiccomposition of the Mediterranean Sea since the Last Glacial Maximum: constrainsfrom pore water analyses. Earth and Planetary Science Letters 192, 1–14.

Romaniello, L., Quarta, G., Mastronuzzi, G., D'Elia, M., Calcagnile, L., 2008. 14C ageanomalies in modern land snails shell carbonate from Southern Italy. QuaternaryGeochronology 3, 68–75.

Rossignol-Strick, M., 1999. The Holocene climatic optimum and pollen records ofsapropel 1 in the eastern Mediterranean 9000–6000. Quaternary Science Review18, 515–530.

Sadori, L., Narcisi, B., 2001. The Postglacial record of environmental history from Lago diPergusa. The Holocene 11, 655–670.

Sala, B., 1983. Variation climatique et sequenze chronologiques sur la base des variationsdes association fauniques a grands mammifers. Rivista di Scienze Preistoriche 38,161–180.

Schwarcz, H.P., Rink,W.L., 2001. Datingmethods for sediments of caves and rockshelterswith examples from the Mediterranean region. Geoarchaeology 16, 355–371.

Settepassi, F., Verdel, V., 1965. Continental quaternary molluscs of the lower Liri Valley(Southern Latium). Geologica Romana 4, 369–451.

Sprovieri, R., Di Stefano, E., Incarbona, A., Gargano, M.E., 2003. A high-resolution record ofthe last deglaciation in the Sicily Channel based on foraminifera and calcareousnannofossil quantitative distribution. Palaeogeography, Palaeoclimatology, Palaeoe-cology 20, 119–142.

Staubwasser, M., Weiss, H., 2006. Holocene climate and cultural evolution in lateprehistoric–early historic West Asia. Quaternary Research 66, 372–387.

Stevens, R.E., Hedges, R.E.M., 2004. Carbon and nitrogen stable isotope analysis ofnorthwest European horse bone and tooth collagen, 40,000 BP–present: palaeocli-matic interpretation. Quaternary Science Reviews 23, 977–991.

Stott, L.D., 2002. The influence of diet on the δ13C of shell carbon in the pulmonate snailHelix aspersa. Earth and Planetary Science Letters 195, 249–259.

Weninger, B., Jöris, O., 2004. Glacial radiocarbon calibration: the CalPal program. In:Higham, T., Bronk, C., Ramsey, C., Owen, C. (Eds.), Radiocarbon and Archaeology,Oxford University School of Archaeology, St Catherine's College, Oxford, pp. 9–15.

Woodwards, J.C., Goldberg, P., 2001. The Sedimentary records in Mediterranean rock-shelters and caves: archives of environmental change. Geoarchaeology 16, 327–354.

Yanes, Y., Delgado, A., Castillo, C., Alonso, M.R., Ibáñez, M., De la Nuez, J., Kowalewski, M.,2008. Stable isotope (δ18O, δ13C and δD) signatures of recent terrestrial communitiesfrom a low-latitude, oceanic setting: endemic land snails, plants, rain, and carbonatesediments from the eastern Canary Islands. Chemical Geology 249, 377–392.

Yapp, C.Y., 1979. Oxygen and carbon isotopemeasurements of land snail shell carbonate.Geochimica et Cosmoschimica Acta 43, 629–635.

Zanchetta, G., Leone, G., Fallick, A.E., Bonadonna, F.P., 2005. Oxygen isotope compositionof living land snail shells: data from Italy. Palaeogeography, Palaeoclimatology,Palaeoecology 223, 20–33.

Zanchetta, G., Borghini, A., Fallick, A.E., Bonadonna, F.P., Leone, G., 2007a. LateQuaternary palaeohydrology of Lake Pergusa (Sicily, southern Italy) as inferredby stable isotopes of lacustrine carbonates. Journal of Paleolimnology 38, 227–239.

Zanchetta, G., Drysdale, R.N., Hellstrom, J.C., Fallick, A.E., Isola, I., Gagan, M.K., Pareschi,M.T., 2007b. Enhanced rainfall in the Western Mediterranean during deposition ofsapropel S1: stalagmite evidence from Corchia cave (Central Italy). QuarternaryScience Reviews 26, 279–286.