First evidence of heat treatment during the early Neolithicin northeastern Italy

Fabio Santaniello a, *, Stefano Grimaldi a, c, Annaluisa Pedrotti a, Stefano Gialanella b

a Dipartimento di Lettere e Filosofia, Universit!a degli Studi di Trento, via T. Gar 14, I-38122 Trento, Italyb Dipartimento di Ingegneria Industriale, Universit!a degli Studi di Trento, via Sommarive 9, I-38123 Trento, Italyc Istituto Italiano di Paleontologia Umana, Anagni, Italy

a r t i c l e i n f o

Article history:Available online xxx

Keywords:Early NeolithicLa VelaLithic technologyFTIR analysesHeat treatment

a b s t r a c t

The site of La Vela sector VII (Trentino-Alto Adige e Italy), provides one of the few complete stratigraphicsequences, ranging from the Mesolithic to the middle Neolithic, in northwestern Italy. The site is locatedin the Adige valley, a way of communication between the Po plan and the Alps. This research focuses onthe early Neolithic lithics ascribable to the Gaban facies, dated to 5000e4700 cal BC. Different rocks,coming from local exposures, have been exploited. The goal of the reduction sequence was the pro-duction of blades by pressure knapping technique. The technological study of the assemblage raised aparticular interest for the presence of flint artifacts suggesting the usage of controlled heat treatment.The presence of this technique has been tested by an experimental approach based on Fourier-Transforminfrared (FT-IR) spectroscopy. Complementary microstructural and analytical characterizations with low-vacuum scanning electron microscopy (LVSEM) observations combined with energy dispersive X-rayspectroscopy (EDXS) have been performed. The analyses confirm the presence of artifacts intentionallyheat treated. The thermal treatment, achieved in order to increase the quality of the blade production, isthe first evidence of this technique in northeastern Italy during the early Neolithic.

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1. Introduction

The controlled heating of siliceous rocks, in order to amelioratethe knapping quality of the raw material, has been investigatedsince a comparatively long time, with early systematic works on thesubject dating to the 1960s and 1970 (see among others Crabtreeand Butler, 1964; Flenniken and Garrison, 1975). The heat treat-ment improves the fracture behavior of the materials with partic-ular reference to fracture toughness (Domanski and Webb, 1992),thus increasing the knapper's control over the rock with a conse-quent improvement of the quality and efficiency of the lithic toolproduction.

The observation of colors changes (rubefaction, whitening)and the presence a greasy/glossy surfaces, caused by micro-structural and crystallographic transformations of the artifacts, isa first macroscopic approach to infer the adoption of specific heattreatments (Crabtree and Butler, 1964; Inizan et al., 1995;

Tiffagom, 1998; Tixier and Inizan, 2000). Unfortunately, thetaphonomic processes can alter the aspect of artifacts causing theformation of other types of patination/modification and making itdifficult to detect possible heat treatments (Crabtree and Butler,1964; Boix Calbet, 2012; Schmidt et al., 2013a). The debateabout the transformations of the rock's proprieties is still open(Domanski and Webb, 1992; Domanski et al., 1994; Schmidt et al.,2012), but several authors proposed different approaches todetect these modifications and verify the usage of the controlledheating in artifact manufacturing (Melcher and Zimmerman,1977; Griffiths et al., 1986; Borradaile et al., 1993; Schmidtet al., 2013a).

The oldest evidence of heat treatment of flint materials hasbeen proposed for the Middle Stone Age in South Africa (Brownet al., 2009; Mourre et al., 2010; Schmidt et al., 2013b). In Israel,the Upper Paleolithic assemblage from Manot cave was inten-tionally heated in antiquity (Weiner et al., 2015). Bordes (1969)highlighted the heat treatment in the French Solutrean as wellas Tiffagom (1998) in Spain. Archaeological evidence of thistechnique has also been discovered in Poland for Mesolithic andBronze Age assemblages (Domanski et al., 2009). In SouthwestGermany, thermal pre-treatment has been suggested for several

* Corresponding author.E-mail address: fabio.santaniello@unitn.it (F. Santaniello).

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early Mesolithic inventories (Eriksen, 1997, 2006). During theearly Neolithic, the use of pre-heated flint cores, in order toimprove blade production, is attested in Spain (Perales Barr"onet al., 2015). In France, during the Neolithic, the intentional heattreatment has been recognized in various archaeological recordsof the Chassey culture (Binder and Gassin, 1988; Lea, 2005; L"eaet al., 2007; Schmidt et al., 2013a). In northern Italy, onlymacroscopic evidence of heat treatment has been suggested forthe late Neolithic site of Botteghino (Mazzieri and Dal Santo,2007) and for some Neolithic surface findings of Buttrio(Duches, 2009).

To the best of our knowledge, the few possible cases in Italyconcerning heat treatment have not yet been proved byarchaeometric investigations. In this framework, the Neolithicsite of La Vela (Fig. 1A), a few kilometers north of Trento (AdigeValley, Italy), is raising a particular interest for the presence offlint artifacts probably produced after controlled heattreatments.

This study is part of a broader research on the early Neolithic ofnortheastern Italy. In this region, La Vela site (sector VII) providesone of the few complete stratigraphic sequences, ranging from theMesolithic to the middle Neolithic, i.e., to the Square Mouth Potteryfacies (Pedrotti et al., 1998).

In this research, a complete identification and attribution of rawmaterials has been conducted on the lithic assemblage. Further-more, the technological analyses allowed recognition of thereduction sequence. On the basis of these results, particularattention has been paid to the usage of heat treatment. For thispurpose, an experimental approach based on Fourier-Transforminfrared (FT-IR) spectroscopy has been adopted. For the comple-mentary microstructural and analytical characterization of thematerial samples, low-vacuum scanning electron microscopy(LVSEM) observations combined with energy dispersive X-rayspectroscopy (EDXS) analyses have been conducted.

2. Settings

2.1. Regional settings

The Adige valley (Fig. 1B), spanning from the Alps to the Venetoregion, is connected with several lateral valleys (Non valley, Grestavalley, Valsugana, Fiemme valley) creating an extended networkbetween the Po plain and the Alps. This region, as awhole, is part ofthe southwestern Alps and it is characterized by a remarkablegeological uniformity. It is almost exclusively composed of car-bonate rocks (limestone and dolomite) and a few volcanic ones(porphyry) (Cassinis and Perrotti, 2007; Tomasoni et al., 2009;Barbieri et al., 2013). The morphology of the valley was influencedby tectonic and glacial events and by the fluvial genesis of the Adigeriver (Fuganti et al., 2001). The river is 410 km long and is connectedto a hydrographic basin of 12200 km2. The Adige springs are nearthe Reschen pass, close to the border between Austria and Italy. Theriver crosses the Alps, fromnorth to south, and it touches the Lessiniand Baldo mountains before entering the Veneto plain. The Lessinimountains consist of calcareous formations, where intense karstactivity is attested and where are located the most important flintcrops of northeastern Italy (Barfield,1990; Cavulli et al., 2002; Longoet al., 2004). The river activity has characterized the surroundingsand influenced the progressive diffusion of the population into themountain area. From the Holocene, after the climatic improvementand global stability, the valley underwent progressive forestation.This stable phase is characterized by aggradation events occurringin conjunction with pedogenesis and anthropic activity (Bassettiand Borsato, 2007; Angelucci and Bassetti, 2009).

2.2. Cultural settings

During the early Neolithic, northern Italy provides a mosaicof cultural facies: Gaban, Fiorano, Vh!o, Isolino, Fagnigola, Samar

Fig. 1. La Vela VII: A) Location of the site and the raw materials provenance areas (1-Adige valley, 2-Bondone and Lessini mountains, 3-Non valley); B) Overview of the alluvial fanand site position inside the Adige valley (photo: D.E. Angelucci); C) Map of the site with the studied layers; D) Section 13: Stratigraphy of the site (from the bottom to the top:Orange: Mesolithic; Yellow: early Neolithic/Gaban facies; Grey: middle Neolithic/VBQI facies; Black: middle Neolithic/VBQII facies). (For interpretation of the references to colour inthis figure legend, the reader is referred to the web version of this article.).

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denchia, all typologically determined (Biagi et al., 1993; Improtaand Pessina, 1998; Pedrotti, 2001; Pessina and Tin"e, 2008). TheAdige valley is marked by the presence of the Gaban facies,dated to 5000e4700 cal BC. This facies has been identified inthe eponymous site, Gaban rock shelter (Trento, Italy). Otherrelevant sites are reported in the same district of Trento(Acquaviva di Besenello, Mezzocorona, Doss Trento, MolettaPatone, Pradestel, Romagnano) and in the nearby Bolzano's one(Aica di Fi!e, San Giacomo, Terlano, Villandro) (Bagolini, 1988;Pedrotti, 2001, 2002; Pessina and Tin"e, 2008). The ceramicproduction of Gaban facies is characterized by the presence ofcarinate mono-handled cups, tronco-conical cups, and vaseswith vertical-strap handles. The ornaments are obtainedby incision, impression, and graffiti. In some instances, bosseson the careens and handles are present. The main decorativemotives consist of bands decorated with grid, zig-zag bands,digital impressions, and nail marks. Concerning the lithic as-semblages, the Gaban facies show a high laminarity and typo-logical features comparable with the Mesolithic tradition(Bagolini and Biagi, 1977; Bagolini and Pedrotti, 1998; Pessinaand Tin"e, 2008).

2.3. The site

The open-air site of La Vela (46!0405200N e 11!0600500E) islocated on the alluvial fan created by the homonymous stream,northwest of Trento, on the hydrographic right of the Adige river.The site was known since the 1960s and it was excavated invarious sectors (IeIX). This paper is focused on the earlyNeolithic assemblage (Gaban facies) of sector VII (Fig. 1C),excavated in 1987e1988 by the CORA cooperative, on behalf ofthe Ufficio dei Beni Archeologici della provincia autonoma diTrento, under the direction of Bernardino Bagolini (TrentoUniversity).

The stratigraphy (Fig. 1D) of La Vela VII covers a wide chro-nological range, from the Mesolithic to the middle Neolithic(Pedrotti, 1990; Degasperi and Pedrotti, 2001). Particularly, thesite is known for the presence of several burials of the SquareMouth Pottery facies (Barfield, 1970; Bagolini, 1990; Degasperiand Pedrotti, 2001). The extended occupation of the site isdirectly linked to its elevated position that looks to the valley, incontact with two environments: a) the Adige valley in front ofthe alluvial fan; b) the valley created by the Vela stream, on theback of the alluvial fan, which easily connects the site to amountainous area. Thus, the possibility of controlling the terri-tory as well as the accessibility to different kinds of resourceswithin a short distance from the site was certainly taken intoaccount during the various frequentations. The archaeologicalarea was affected by alluvial and torrential events and is locatedclose to the palaeochannel of the stream itself (Mottes, 2007), asconfirmed by the presence of some alluvial layers, alternatedwith silt-sandy deposits, which underwent pedogenesis pro-cesses (Bagolini et al., 1975). During the Neolithic, the area

downstream in front of the site was of a swamp area, withmeander lakes formed by abandoned channels of the Adige river.During the early Neolithic, hunting was still common. Deer wasthe most represented species, even if domestic animals werealready present (Bazzanella, 2001). The forest was characterizedby the presence of a mixed oak forest (Palumbo, 2009). Agri-culture is attested by the presence of cereals, legumes, fruits, andinvasive plants in other sectors of the site (La Vela II and III).Identified species include Triticum timopheevi probably origi-nating from the east, and the common dogwood, perhaps used intints or lighting oil (Mottes and Rottoli, 2006; Mottes, 2007).

3. Materials

3.1. The lithic assemblage: raw materials provenance

Different stratigraphic units attributable to the Gaban facieshave been analyzed: SU 27, 28, 71 and 197 (194 lithic artifacts)(Table 1). As far as the provenance of raw materials is concerned,the lithic assemblage from La Vela VII is made of various types ofrocks. Particularly, the exploitation of three geological forma-tions containing flint has been assessed: Scaglia rossa, Biancone(or Maiolica) and Scaglia variegata. These formations are atypical sequence in the entire region (Castellarin et al., 2005;Avanzini et al., 2010, 2012). The Scaglia rossa Formation (Albiansup. e Eocene inf.) is a red/red-brown micritic limestones withplanktonic foraminifera (Globotruncana and Heterohelicida).Scaglia variegata (Aptian e Cenomanian) is represented bymicritic limestones of different colors (grey, green, rose) withRadiolarites and other bioturbated foraminifera. The Biancone(Tithonian sup. e Aptian inf.) has very thin micritic limestoneswith variable coloration (grey, white) with Radiolarites andTinttinids. The supply areas exploited during the Neolithicfrequentation of la Vela are difficult to be ascertained because oftheir ubiquity in the region and the uplifting events thatdisturbed the geological successions (Bertola, 2005, 2012).However, previous, in some cases comparatively recent, research(Barfield, 1990; Bertola and Cusinato, 2004; Longo et al., 2004;Avanzini and Caldonazzi, 2006; Bertola, 2012; Barbieri et al.,2013), characterized materials from the valley and adjacentareas, so that the following three main provenance areas can betentatively put forward. The Scaglia Rossa is known from the Nonvalley to Lessini mountains, but its outcrops are quite commoninside the Adige valley, near the la Vela site, between the Bon-done mount and Gresta valley on the right side of the Adige river(20e5 km from the site). The Scaglia Variegata outcrops are rarein the Adige valley, but are more abundant in the Non valley(30e50 km from the site) and sporadically also on the Lessinimountains. Finally, Biancone, more to the south, between theBaldo mount and the Lessini mountains (about 70 km from thesite) is frequently noted, while it is rare inside the Adige valley(Compare Fig. 1A).

Table 1La Vela VII, early Neolithic lithic assemblage divided by stratigraphic units and raw materials (Sr e Scaglia rossa; B e Biancone; Sv e Scaglia variegata; IND e Indetermined).

Blades Elongated blanks Flakes Cores Others

Sr B Sv IND Sr B Sv IND Sr B Sv IND Sr B Sv IND Sr B Sv IND

SU27 4 11 2 0 1 4 0 0 8 13 1 0 1 2 0 0 7 1 0 0 55SU28 11 5 0 1 5 3 0 0 13 2 0 1 4 0 0 0 7 3 2 2 59SU71 13 6 3 2 5 1 0 0 8 2 1 2 1 0 0 1 1 0 1 0 47SU197 1 8 4 0 1 2 2 0 5 6 2 0 0 1 0 0 1 0 0 0 33

29 30 9 3 12 10 2 0 34 23 4 3 6 3 0 1 16 4 3 2 194

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3.2. The lithic assemblage: technological analysis

With the aim to recognize the relation between rock provenanceand techno-economical assessment of the site, we reconstructedthe reduction sequence interpreting each blank and comparing itwith the different raw materials (see among others Andrefsky,1994; Geneste, 1989). The goal of the reduction sequence is theproduction of blades and elongated blanks by unidirectionald"ebitage (Fig. 2A). The Scaglia rossa flint represents the largest partof the assemblage, the Biancone is frequently exploited, and theScaglia variegata is sporadically noted (Fig. 2B). Only 11 retouchedartifacts (Table 2) have been recognized, generally made of Bian-cone (64%) and more rarely of Scaglia rossa (27%) and Scaglia var-iegata (9%).

The cores are made from blocks/slabs, rarely from pebbles. Theinitialization, attested by the presence of cortical and semi-corticalflakes (Fig. 3A), is made by direct percussion. The laminar pro-duction, made by pressure-knapping technique, presents theexploitation of a single striking platform. Generally, the blades havea faceted butt (Fig. 3B). Similarly, the striking-platforms of the coresare prepared by detaching tiny flakes from the debitage surface tothe platform (Fig. 3C), while abrasions of the overhang are rarelyobserved.

The reduction sequence reconstruction shows that the threetypes of rocks were similarly exploited on-site. The presence of very

regular long blades made from Biancone and Scaglia variegatasuggest that these artifacts were imported into the site alreadyshaped; this could be confirmed by the presence of few, small coresmade from thesematerials. The length/width ratio on the unbrokenblades (Fig. 4A) confirms that some artefacts made from Bianconeand Scaglia Variegata are frequently longer than the Scaglia rossaones. Moreover, the longest Biancone blade RR179 (Fig. 4B) hasbeen shaped in a Ripabianca burin (Broglio and Lollini, 1963), aformal tool frequently noted outside the Adige valley in the Fioranofacies. Finally, the technological analysis highlighted the presenceof glossy surfaces and different patinations on some artifacts madefrom Scaglia rossa (Fig. 3 B and C), suggesting the use of the heattreatment (see among others Inizan et al. 1995; Tixier and Inizan,2000).

4. Experimental methodology and techniques

As a direct consequence of the technological analysis, the focusof the present study is to assess the actual use of heat treatment inthe manufacturing of flint artifacts from La Vela site. Severalexperimental methodologies have been proposed over the years forthe identification of heated flints, involving thermoluminescence,paleomagnetism, morphological features such as pot-lid fractures(Weiner et al., 2015), and mechanical properties such as hardnessand fracture toughness (Domanski et al., 2009). Fourier-Transforminfrared (FT-IR) spectroscopy is particularly effective in this sortof study, as it is capable of revealing the occurrence in the flintmaterial of those microstructural and crystallographic changes thatare regarded to be the main reasons for the improved workability,by knapping, of heated flint materials (Schmidt et al., 2013a;Weiner et al., 2015). The changes brought about by flint heattreatment can be mainly ascribed to a reduction or completeelimination of open porosity and contemporary release of molec-ular water, forming SieOH bonds inside the quartz structure(Schmidt et al., 2011, 2012). The main vibrational modes associatedwith the SieOH bonds have their maxima at 4545 cm"1, 4469 cm"1

and 4345 cm"1. The first two components change their reciprocalintensities in the hydrated and de-hydrated conditions (Fig. 5A). Inthe present study the hydrated conditions refers to geologicalScaglia rossa sample in the original conditions whereas the dehy-drated conditions has been obtained by heat treating a sample for1 h at 500! (Fig. 5B). Relevant dehydration of flint material is thatinduced by possible heat treatments during the manufacture offlint artifacts, typically at temperatures in excess of 200 !C. For thisreason, Schmidt et al. (2011; 2013a) have proposed the intensityratio of the IR lines at 4545 cm"1 and 4469 cm"1 as a reliable in-dicator of the material heat treatment, with the additional advan-tage that the approach is fully non-destructive. FT-IR tests can becarried out on the archaeological flint objects directly, provided thethickness of the sampled region is in the comparatively broad rangeof 0.5 mm up to 4 mm.

Here, we have adopted the above approach to analyze the Sca-glia rossa lithics. In order to calibrate the IR spectrometer, ageological sample of Scaglia rossa, collected in a local outcrop(codename SV4 in Barbieri et al., 2013), has been cut with a pre-cision diamond saw, producing sheets with different thickness.After a drying out thermal treatment of 1 h at 60 !C, tests conducted

Table 2La Vela VII, early Neolithic retouched pieces divided by raw materials.

Burins End-scrapers Points Side-Scapers Truncations Marginal

Scaglia rossa 2 0 0 0 1 0 3Biancone 2 1 1 1 0 2 7Scaglia variegata 0 0 0 0 1 0 1TOT 4 1 1 1 2 2 11

Fig. 2. La Vela VII, early Neolithic percentage distribution: A) Blanks; B) Raw materials.

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on these sheets indicate that the sample thickness affording thebest FT-IR results was 1.3 mm. This indication was used as aguideline not only to select all the suitable archaeological samples(Table 3) but also to identify the best testing region on their surface.As an additional parameter, the IR beam has a spot size of approx.1 mm. The Scaglia rossa reference slab was subsequently heat

treated at 500 !C for 1 h in air (Table 3). This sample, a set of tenuntreated Scaglia rossa flakes and the archaeological samples weresubsequently immersed in deionized water for at least 48 h beforeproceeding with IR tests. Each sample was extracted from thewater, dried with a towel and insertedwith the help of adaptable Alframe into the IR spectrometer. To characterize the microstructural

Fig. 3. La Vela VII, early Neolithic reduction sequence: A) Cortical flake (Scaglia Rossa); B) RR 198 Blade made by pressure-knapping technique (Scaglia Rossa); C) RR 206 Coreexploited by pressure-knapping technique (Scaglia Rossa).

Fig. 4. La Vela VII, early Neolithic assemblage: A) Length-width ratio of the blades; B) RR179 Ripabianca burin (Biancone).

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Fig. 5. La Vela VII, FTIR spectra showing the SiOH band interesting to detect possible heat treatments in flint materials: A) Untreated Scaglia Rossa flint sample. The intensity ratio ofthe two lines indicated is sensitive to the hydration condition of the flint material. B) Comparison between treated (at 500 !C) and untreated Scaglia Rossa flint sample, used tocalibrate the IR protocol.

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changes induced by the possible heat treatment of the archaeo-logical artifacts, LV SEM observations were conducted. This electronmicroscopy technique is particularly suited for this kind of obser-vations on archaeological flint artifacts, as no conductive coating isrequired to observe a non-conductive material, such as flint, thanksto the electrical discharging effect of the residual gas atmosphere.On this occasion, a residual water vapor pressure of 0.4 torr wasused for acquiring secondary and backscattered electron imagesusing a primary beam acceleration voltage of 20 kV.

5. Results and discussion

The tests conducted on the standard geological sample in the as-received (AR) condition and after the thermal treatments describedin the previous paragraph, provided clear indications of the varia-tion range for the intensity ratios of the IR lines 4545/4469. In Fig. 6,the ratio for each analysed sample is shown. The standard SV4materials in the as-received condition and after thermal treatmentsat 500 !C (sample number 18 and 19, Table 3) display the following

Table 3La Vela VII, summary table with all the analysed archaeological samples from the La Vela site (1e17). Geological samples (18e19), used to calibrate the IR set up and with theindication of the relevant heat treatment condition, are also listed. Sample number used for plotting the 4545/4469 intensity ratio (compare Fig. 6).

Sample number Code 4545 cm"1/4469 cm"1 Raw material Blank

1 RR438 1.017 Scaglia rossa flake2 RR664 1.108 Scaglia rossa blade3 RR10000 1.309 Scaglia rossa blade4 RR632 0.900 Scaglia rossa elongated blank5 RR1034 0.937 Scaglia rossa blade6 RR194 0.913 Scaglia rossa blade7 RR193 1.027 Scaglia rossa blade8 RR1044 1.022 Scaglia rossa blade9 RR205 0.944 Scaglia rossa blade10 RR1027 1.073 Scaglia rossa blade11 RR189 1.053 Scaglia rossa blade12 RR198 1.130 Scaglia rossa blade13 RR631 0.892 Scaglia rossa blade14 RR635 0.847 Scaglia rossa elongated blank15 RR1056 1.171 Scaglia rossa blade16 RR995 1.148 Scaglia rossa blade17 RR191 0.913 Scaglia rossa blade18 SV4 AR 0.879 Scaglia rossa geological slabs19 SV4 500 !C 1.119 Scaglia rossa geological slab

Fig. 6. La Vela VII, graph with the intensity ratios of the IR lines at 4545 cm"1 and 4469 cm"1. Rhombuses correspond to archaeological samples; square to untreated geologicalsamples (please note, this point corresponds to the average value obtained from ten samples); triangle corresponds to geological sample heat treated at 500! . All details on artifactsand heat treatment conditions can be found in Table 3. Error bar for intensity ratio data points: 0.001.

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values for the 4545/4469 ratios: 0.879 and 1.119 respectively. Thefirst value, in agreement with the literature (Schmidt et al., 2013a),can be regarded as the typical ratio of an untreated material ortreated at too low temperatures (and times) to promote a dehy-dration. In this respect, the actual size of the involved pieces isparamount, in view of the different path length that water shouldtravel in its way out of the flint material (Schmidt, 2014). The 4545/4469 ratio for the sample treated at 500 !C, is fully compatible witha fully dehydrated condition. The archaeological samples (samplenumber from 1 to 17, Table 3) display 4545/4469 ratios largelyfalling in the variation range for hydrated and dehydratedmaterials(Fig. 6), as identified by the standard samples. On the other hand,the fluctuations that can be noticed are compatible both with theheterogeneity of the raw material and with the uncontrolledtreatment conditions that can be envisaged for the archaeologicalartefacts.

To check for the actual microstructural difference between atreated and untreated samples (Domanski and Webb, 1992), LVSEM observations were carried out on a certainly untreated, i.e.,sample RR664 (Fig. 7A), and one that was certainly heat treated, i.e.,sample RR198 (Fig. 7B). The images display quite distinctively thedifferences between the two surfaces: quite rough with diffusemicrocracking on the surface of the untreated RR664 material;smooth and apparently more compact on the sample RR198. Thesefeatures are compatible with the expected changes and relevantimprovements in the workability of the flint material introduced bycontrolled heat treatments. A smoother fracture surface iscompatible with a reduction in open porosity, one of the reportedchanges associatedwith the heat treatment of the flint material andthe formation of longer and sharper chips during knapping. On theother hand, the rougher fracture surface displayed by the untreatedmaterial would explain a lowerworkability, for the deflection of thefracture propagation by the microstructural inhomogeneities pre-sent in the raw material.

6. Conclusions and further developments

As concerns the archaeometric investigations, the proposedexperimental approach, based on the combined use of FT-IR spec-troscopy and LV SEM, confirms the possibility that flint knappinginvolved deliberate and controlled heat treatments, at the site of LaVela VII. This is the first confirmed evidence of heat treatment innortheastern Italy during the early Neolithic.

The results obtained from materials characterization draw arelationship between structural and microstructural changesinduced by heat treatments, as detectable by FT-IR spectroscopy,and the resulting texture of the fracture surface, as observed inLV SEM images. In view of the close relationship between ma-terial inner (micro)structure and its fracture surface appearance,this information can be profitably exploited in case, for instance,FT-IR spectroscopy cannot be used on a large, thick, materialsample. In this case, LV SEM observations only may be used tosuggest if a flint sample was heated or not. An application of thisidea is proposed to verify whether the core RR206 (compareFig. 3C) was thermally treated, as the macroscopic feature seemsto indicate. The surface morphology observed with LV SEM(Fig. 7C) seems to confirm the hypothesis of the thermal treat-ment for this core.

At the present state of knowledge, heat treatment at La VelaVII is attested only on the Scaglia rossa while macroscopic evi-dence of heat treatment on Biancone or Scaglia variegata islacking. As suggested for some Iberian Neolithic sites (Morgadoand Pelegrin, 2012), the use of the heat treatment at la Vela isrelated to the blade production by pressure knapping. In theinvestigated area, the use of the pressure technique has been

already proposed for some Mesolithic sites including Romag-nano and Gaban rock shelters (TN) (Binder et al., 2012) and forthe early Neolithic site of Lugo di Grezzana (VR) (Moser, 2000,2002). The use of the thermal treatment was reported, only ac-cording to macroscopical evidence, for a few sites without in-ferences of the production cycle (Mazzieri and Dal Santo, 2007;Duches, 2009).

The use of heat treatment on the local Scaglia rossa suggests atechno-economical behavior related to: a) the easy availability of

Fig. 7. La Vela VII, LV SEM micrographs comparing the microstructure of: A) RR664untreated; B) RR198 treated; C) Microstructure of the core RR206, displaying a surfacetopography resembling that of a heated sample RR198 (see text for further comments).

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Scaglia rossa outcrops and b) the use of heat treatment as a deviceto improve the blade production. Other rocks were probably sha-ped without thermal treatment or they were directly imported asfinished products (RR179, compare Fig. 4B).

The study will be extended to other finds of the site, to providefurther data and higher statistical significance and reliability to therelevant archaeological outcomes. Particularly, the same protocolwill be tuned for the other rawmaterials found in the site. Finally, itcould be useful to test if other sites in Adige valley and its prox-imities provide similar evidence in order to verify where thisbehavior is attested considering the cultural and the environmentalvariability of the area.

Acknowledgments

The study was supported by the Scuola di dottorato in StudiUmanistici, Dept. of Humanities (UNITN, Italy). A special thank toDidier Binder (CEPAM, Nice) and Niccol!o Mazzucco (CSIC, Barce-lone) for their suggestions. We would like to thank Luca Benedettiand Angela Berloffa (Dept. of Engineering e UNITN, Italy) for theirtechnical support in carrying out FT-IR analyses and Paolo Chist!e(Laboratorio di Microfilm e Fotografia digitale e UNITN, Italy) forimages elaboration. Finally, we are grateful to Fabio Cavulli, DiegoAngelucci and Giacomo Comencini (Laboratorio Bagolini e UNITN,Italy) for their support and friendship. F.S. and S.Gr. designed theresearch and performed technological analyses; S.Gi. performedarcheometrical analyses; A.P. performed the chrono-culturalassessment of the site. All the authors wrote the paper.

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