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Introduction        The site of Pi        é        gu is located in Brittany         (        48°35’49 N and 2°33’08 W)                 at the westernmost end of Europe        (fig.1 / A &#38; B). Study of the Western section of the cliff started        in 1987 in very difficult conditions (Monnier &#38;         Hallégouët,         1997) because the steepness of the        cliff and the rescue terms (fig.2). The initial research concentrated        on the cliff itself but more data were also obtained from a        neighboring beach and in a reentrant of the cliff located more to the        East.         The site of         Pi        é        gu         is famous for its archaeological        artifacts. It was first described by Monnier (1973; 1974; 1976 &#38;        1980) and latter in preliminary reports (Hallégouët         et al        ., 1987; Van Vliet-Lanoë         et al        ., 1997)         dealing with         the flint industry, the findings        associated with the offshore geological drillings and with the        cuttings obtained in trenches opened for water supply (Hallégouët                et al        ., 1987) (fig. 1 / C). Contrary to the        flint industry which was mainly found in the actual beach and which is        characteristic of the         Levalloisian         style (Monnier         et al        ., 1985) many remains of big mammal        have been recovered in the cliff itself         (Auguste         et al        ., 2005)        . The stratigraphy of the Pleistocene        deposits which constitute the Western section was first based on        archaeological artifacts.         The various authors which were        involved in this study and which have been working to strengthen the        initial archaeological dating were Auguste, Lefebvre, Keen, Brebion        &#38; Lauriat-Rage (in Keen         et al        ., 1997). It is important to stress        that it exists now a few buildings at the place of the Eastern        excavations and that a large concrete wall was built against        landslides, front of the Piégu cliff itself, which prevents any        re-sampling of the site.         Despite all the previous researches        done in this area, a full stratigraphic description of the site has        never been presented. The main purpose of this paper is to describe        the stratigraphic subdivisions recorded in this site and to summarize        briefly some of the preexisting palaeontological data in order to        compare the previously published results with the malacological        determinations developed for this study. At last we will present an        overview of the environment which prevailed in this area during the        sediments deposition.              Figure 1: A. General situation of the        Pi        é        gu site in Westernmost Europe. B.        Location of Pi        é        gu in the framework of the        Saint-Brieuc Bay. C. Location of the drillings (1), composite profiles        (2), Eastern onshore excavation (3), trenches (4) and Western onshore        excavation (5).        Figure 1 : A. Situation générale du          site de Piégu à l’extrême ouest de l’Europe. B. Localisation de          Piégu dans le cadre de la                 Baie de Saint-Brieuc. C.          Localisation des sondages (1), profils reconstitués (2), fouille à          terre à l’est (3), tranchées (4) et excavation à l’est sous l’estran          (5).                            W – Western onshore excavation; E –        Eastern onshore excavation; O – Offshore boreholes. (A &#38; B        by).        W – Excavation Ouest; E – Excavation          Est à terre; O – Sondages sous l’estran. (A &#38; B by                   http://maps.google.ru/maps?            hl=ru&#38;tab=wl                ).              Figure 2: General view of the Piégu        site. The paleo-dale filled with carbonated sands is visible above the        frost shattered screes.        Figure 2 : Vue générale du site de          Piégu en cours de fouille. On voit le paléo-vallon rempli par des          sables carbonatés, au-dessus des éboulis de blocailles.                            General backgroundLocal stratigraphy and correlation with the      international stratigraphical subdivisions        All the stratigraphical divisions and        ages attributed to the Quaternary layers studied in the Northern part        of Brittany are based on the global framework established by Monnier        (1973, 1979, 1980; Bigot &#38; Monnier, 1987; Monnier &#38; Bigot,        1987; Loyer         et al        ., 1995; Monnier         et al        ., 2011). It relies on the        sedimentological similarities existing between dated and undated        sections known in the same area. Recently, a correlation of these        formations with the marine isotope stages has been proposed (Monnier,        2006). The following estimations are now accepted by all Quaternary        researchers working in Brittany: The Formation of Nantois corresponds        with MIS 6 to 10 (330 – 127 ka). The Formation of La Haute-Ville can        be correlated with MIS 5 (127 – 75 ka). The Formation of Port-Morvan        spreads between MIS 4 and the beginning of MIS 3 (75 – 40 ka). The        Formation of Sable-d’Or-les-Pins developed between the second half of        MIS 3 and MIS 2 (40 – 15 ka). A correlation between the Middle and        Upper Pleistocene subdivisions of Northern Brittany and other units of        Western Europe is proposed in Table 1.      Table 1: Comparison between the      Middle to Upper Pleistocene stratigraphic units previously recognized in      the Northern part of Brittany with known successions of Westernmost      Europe.Tableau 1 : Comparaison entre les          unités stratigraphiques du Pléistocène moyen et supérieur          antérieurement reconnues dans le nord de la Bretagne avec les          successions connues à l’extrême ouest de l’Europe.                       *The West European stratigraphic divisions for the      Upper Middle Pleistocene are given according to Busschers      et al. 2008 and to Turner (1998), and the      Late Pleistocene divisions according to      Zagwijn (1996).* Les divisions stratigraphiques          pour le Pléistocène moyen sont données d’après Busschers et al. 2008          et Turner (1998), et les divisions du Pléistocène supérieur d’après          Zagwijn (1996).Archaeological background        A summary of the many studies        developed on the Pi        é        gu artifacts has been made by Monnier                et al        . (1985), Monnier &#38; Hallégouët        (1997a) and Hallégouët         et al        . (1993). We will just remember here        briefly the situation of this outcrop in the archaeological history of        Brittany. This settlement corresponds to an old rocky shelter located        in the lowest part of a cliff which was inhabited during a regressive        marine episode. It was conveniently exposed to the South in a        reentrant of the cliff. The industry is mainly made of flints which        belong to the Levalloisian technique (Monnier         et al        ., 1985). Study of the archaeological        excavation permitted to understand that there were three periods of        Palaeolithic dwelling:      a/ A small handaxe found on the lower      fossil beach (fig. 3, Layer B, MIS 9) corresponds to a first      occupation.        Figure 3: Profile of the Western        onshore section of Pi        é        gu (Van Vliet-Lanoë         et al.        , 1997) with author corrections.                Figure 3 : Profil de la section          Ouest (Van Vliet-Lanoë et al., 1997) avec corrections des auteurs.                                              Same lithological captions as for        Figure 4. The description of the lithology of the various layers is        given in Table 2.        Même légende lithologique que pour          la Figure 4. La description de la lithologie des différentes couches          est donnée dans le Tableau 2.      b/ An indurated soil resting on a fossil      beach (fig. 3 Layer F, MIS 7) testifies of a second occupation (this      situation is usual in Brittany where re-entrants located at the base of      cliffs often acted as shelters during marine regressions).        c/ A butchering site, first located        on top of the cliff but which collapsed during a warmer episode        involving bones and flaked flints mixed with fallen debris (fig. 3,        Layer G) represents the third occupation. The second level of        occupation corresponds to a Lower Middle Palaeolithic episode        characterized by a Levalloisian method and many Levalloisian points.        The butchery site could be more or less of the same age (Monnier                et al        ., 2011; Bahain         et al        ., 2012).      We will see latter that a Saalian age can      be attributed to these main settlements on the basis of stratigraphic      evidences, which has been confirmed recently by radiometric datations.      In total the industry found in this site belongs to the old Middle      Palaeolithic.Malacological background        Up to now, the available        palaeontological data have only been presented in a field guide (Van        Vliet-Lanoë         et al        ., 1997) where they were given in        tables with few or no comments.              The first results dealing with the        continental and marine molluscs have been listed in Keen         et al        . (1997).         The description of the molluscs found        in the Eastern excavation was based on sample 20 (fig. 4). It shows        the existence of 13 terrestrial species        .         The list of the molluscs found in the        Western excavation (layer J) (fig. 3) has been also given by Keen        (        Keen         et al.,         1997)         which described 8 terrestrial, 3        freshwater and 5 marine taxa. The marine mollusc assemblage found in        the different excavations made in the actual beach (layer H) (fig. 3)        was formerly determined by Lauriat-Rage and Brebion (        Keen         et al.,         1997)        , they were considered to be of        Eemian age.         19 different species of bivalves were        also determined by Lauriat-Rage in the level H of the beach and in 3        drill holes. Brebion has shown that 10 species of gastropods        determined in these samples are still living today.              Figure 4: Profile along the        Pi        é        gu Eastern onshore section.                Figure 4 : Profil selon la section          Est de Piégu à terre.                             1 – soil (horizon A); 2 – soil        (horizon B); 3 – loam; 4 – red clayish sand; 5 – clay; 6 – sandy loam;        7 – loamy sand; 8 – sand; 9 – pebbles; 10 – consolidated pebbly layer        (ancient beach); 11 – carbonate; 12 – location of the numbers        referenced in the molluscs study; 13 – artifacts; 14 – gastropod        shells; 15 – bivalve mollusc shells; 16 – mammal bones. The        description of the lithology of the various layers is given in Table        3.        1 – sol (horizon A); 2 – sol          (horizon B); 3 – limon; 4- sable argileux rouge; 5 – argile; 6 –          limon sableux; 7 – sable limoneux ; 8 – sable; 9 – galets; 10 –          couche consolidée à galets (plage ancienne); 11 – carbonate de          calcium; 12 – localisation des numéros référencés dans l’étude          malacologique; 13 – artefacts; 14 – coquilles de gastéropodes; 15 –          coquilles de mollusques bivalves; 16 – os de mammifères. La          description de la lithologie des différentes couches est donnée dans          le Tableau 3.      In contrast with the previous studies      which were mainly undertaken to strengthen the archaeological      investigations, this work concentrate on the understanding of the      detailed evolution of the complete sections during the Middle      Pleistocene and Holocene times.Former geochronological data        Until recently it was difficult to        compare our stratigraphical reconstruction with the geochronological        data since the few ages which were available were suggesting ages        ranging between 162 and 234 ka for one tooth and 127 to 277 ka for a        few mammal bones. It was clear that these ages were not compatible        with the sedimentary formations of Pi        é        gu when compared with dated sections        known elsewhere in Brittany (Hallégouët         et al        ., 1997; Monnier         et al        ., 1997c). It is the reason why those        ages, which were looking too young or too old, useless to control our        reconstruction, will not be discussed here. The reason for the        imprecision of these data will be presented in the discussion where        the old data will be compared with the recent geochronological        dates.      The new studyMethods and materialsSave for the Western cliff, the      stratigraphical description of the deposits which constitute the Eastern      and Offshore sections was never made before; this description has been      established thanks to field notes, photos and drawings made previously      by two of us (J.L. Monnier and B. Hallégouët).The colors of the natural sediment      (before drying) have been describe with help of the Munsell      Soil Color Charts.        111 samples of the Pi        é        gu site which were still available        have been re-examined for this study. However, because they were        initially sampled during the archaeological excavations,         the volumes of the samples are very        different. They were recalculated for each stratigraphic level and are        now given in Table 5         in cubic decimeters        . The samples were washed using        sieves of         0.5 mm in laboratory conditions. 38        samples were containing mollusc shells. Shells were examined and        extracted individually because the number of mollusc shells is        important in the Pleistocene land deposits. The quantity of extracted        shells was very different depending on the examined level (Table        5).         The gastropods abundance is given        according to the method of Ložek (1964) – we counted the number of        complete shells plus the number of apices or apertures which were        considered as equivalent to one shell when taken together. The        molluscs of associations were classified according to their modern        ecological preferences in air temperature, humidity, and vegetation        cover following the criteria proposed by Ložek (1964), Likharev &#38;        Rammel’meier (1952), and Sümegi (in Wilis         et al        ., 2000).              The determination of th        e species was made according to        Likharev &#38; Rammel’meier (1952), Shileyko (1978, 1984), Shileyko        &#38; Likharev (1986), Kerney &#38; Cameron (1999), the determination        tables and the systematic is given according to Falkner         et al.         (2002).      Stratigraphical      descriptionThe Piégu site is composed of three      separated sections which, taken together, give an idea of      the sedimentation processes which developed      during the Middle, Late Pleistocene and Holocene.The description of the different      layers of the Piégu site is      based on the observations made before (Monnier, 1973) and during the      archeological study of the cliff (Monnier et al., 1985; Monnier &#38;      Hallégouët, 1997a) but also on the data collected during various      drillings surveys made in the neighboring beach and in two trenches open      for water supply. The main problem of this site is the large development      of the coarse slope deposits (represented by fragments of Palaeozoic      rocks) which incorporate only few palaeontological remnants. We also had      sometimes to face the approximate location of some of the samples      collected in the cliff as well as on the beach which arose some      difficulties for their correlation. The excavated layers were numbered      and described from the bottom to the top.The Western onshore      sectionThe Western section is the best known      because of the archaeological artifacts found in it (ig.1 / A / W). The      layers discovered during the excavations and which constitute the      Western onshore section are shown on table 2 and figure 3. In the      stratigraphic description of this section we kept the original lettering      given by van Vliet-Lanoë      et al. (1997).        Table 2:                 Stratigraphical facies identified in        the Western section.        Tableau 2 : Faciès stratigraphiques          identifiés dans la section Ouest.                            Marine deposits0. (A) Marine abrasion      surface.1. (B). Rounded pebbles with molluscs. The      thickness is around 0.3 m. The presence of a      small Palaeolithic flint-made hand axe of      Acheulean style is worthy of note.Slope deposits2. (C). Fragments of Palaeozoic rocks with      traces of frost-shattered screes. The thickness is around 2 to 4      m.Accumulation of marine and aeolian (dune)      deposits3. (D). Brownish yellow (7.5 YR 5/8)      rounded pebbles (old beach) with a thickness of 0.3 to 0.4 m. 4. (E). Dark brown and coarse      non-calcareous very well sorted sand (7.5 YR 5/8) which can be linked      with the pebbly beach. The thickness ranges between 0.2 and 0.4      m.Slope and eluvial deposits (soil)5. (F). Dark brown soil (10 YR 3/3) of a      Palaeolithic settlement located at the level of the beach (layer 9) and      containing flint flakes and tools. Its thickness is of 0.5 m. This soil      is mainly anthropogenic (it is made of a non calcareous blackish humic      sediment containing angular pebbles) which probably incorporate some      slope (colluviums) deposits. The lithic industry (no bones preserved) is      characterized by the Levalloisian flaking style, many Levalloisian      points, many side-scrapers (shaped on one side, two sides or with      oblique convergent reworked sides) have been found. It is a Mousterian      industry (Old Middle Palaeolithic).Slope deposits        6. (G). Angular fragments of        Palaeozoic rocks with frost-shattered screes and numerous bones of        large mammals. The                 presence of Palaeolithic artifacts        must be underlined. The thickness of this layer is up to 3 m. It is        interpreted as a remnant of a butchery station which was previously        located at the top of the cliff and which collapsed down the        slope.      Aeolian deposits (dune) and reworked marine      sands7. (J). Light yellowish brown calcareous      fine-grained sand (10 YR 5/6) with numerous shells of terrestrial and      marine molluscs. The quantity of species and shells decreases towards      the base of the layer. Its thickness ranges from 1.5 to 3 m.Eluvial deposits (soil)8. (K). Yellowish brown (10 YR 5/5) sandy      soil with indeterminate shell detritus. The thickness is up to 0.5      m.During this interval, marine pebbles and      sand (H) accumulated in the beach. The thickness is about 0.2-0.3 m. The      pebbly layer containing marine Bivalve and Gastropod shells is embedded      in a wave-cut notch at the base of the cliff. It is the reason why the      Upper Pleistocene deposits are still preserved.Traces of erosion.Slope deposits9. (I). Angular fragments of Palaeozoic      rocks which size ranges from gravel to blocks in a yellow sandy matrix      (10YR 7/6). Its thickness ranges from 0.5 to 1 m.Aeolian deposits10. (L). Light yellowish grey dust-like      calcareous sandy loam (10 YR 7/6) forming a matrix between soliflucted      blocks. This layer probably corresponds with the base of the Sables d'Or      Les Pins Formation. Its thickness ranges between 0.5 and 1 m.Some traces of weathering can be      observed.Slope      deposits11. (N). Angular fragments of Palaeozoic      rocks of different sizes incorporated in a light grey sandy and loamy      matrix (10 YR 7/1). The thickness ranges from 0.4 m at the top of the      slope to 1.5 m in its lower part.Contemporaneous marine pebbles and sand      accumulated in the modern beach (M).The Eastern onshore sectionThe composite Eastern onshore section was      built up using the local descriptions collected in two trenches and      excavations made in two different areas (fig. 1 / III / B). These data      have been associated in order to present a more continuous stratigraphic      section. They are shown on table 3 and figure 4.        Table 3: Stratigraphical facies        identified in the Eastern section.        Tableau 3 : Faciès stratigraphiques          identifiés dans la section Est.                            Slope-aeolian-marine deposits                  1. Calcareous loam. The excavated          thickness is about 0.2 m.                          2. Thin ferruginated sand layer with          mollusc shell fragments (sample 42). The thickness is up to 0.3          m.                          3. Loamy ferruginated sand with rare          molluscs and shell detritus (samples 39, 40 and 41). The thickness          is up to 0.5 m.                          4. Calcareous loam. The thickness is          up to 0.1-0.2 m.                          5. Loamy sand with rare mollusc shells          (sample 38). The thickness is up to 0.2 m.                          6. Loamy sand (=soil?) with rare          mollusc shells (sample 37). The thickness changes from 0.2 to 0.3          m.                                                  7. Thin sand with             rare molluscs and shell detritus            (sample 36). The thickness is up to 0.3 m.                                    8. Calcareous loam with rare shell          detritus (sample 33). The thickness is up to 0.5 m.                          9. Calcareous loam. The thickness is          up to 0.3 m.                          10. Loam. The thickness is up to 0.3          m.          Traces of weathering              Eluvial-slope deposits                  11. Yellow grey sandy loam (10 YR 7/6)          reworked by soil processes containing artifacts and shell detritus          (samples 43 and 34). The thickness is up to 0.5 m.                          12. Humiferous grey loam (soil) (10 YR          7/1) with shell detritus (samples 35 and 29). The thickness is up to          0.2 m.              Erosional levelAeolian-marine deposits      (dune)                  13. Dark brown sand (7.5 YR 5/8)          containing numerous mollusc shells, with small pebble in the middle          part of the layer and humiferous sand in its lower part (samples 20          and 28). The thickness reaches 0.8 m. Alternation of pebbles          (samples 22, 24 and 9), sand (samples 8, 10 and 30) and consolidated          pebbly layers (samples 23 and 31) with marine molluscs which          replaces the sand at the base of the slope.                          14. Pebble, gravel and sand containing          artifacts. The thickness is of 0.2 m.              Slope deposits                  15. Greyish brown loam (10 YR 5/2)          with rare mollusc shell detritus (samples 27 and 32). The thickness          is around 0.2 m.              Traces of weathering.Eluvial-slope deposits                  16. Light grey calcareous sandy loam          (10 YR 7/1) reworked by soil processes with mollusc shell detritus          (sample 26). The thickness ranges from 0.4 to 0.5 m.              Erosional levelEluvial deposits (podzolic      soil)                              17. Dark grey sandy loam (10 YR            4/1) with rock fragments and numerous mollusc shells            . The thickness ranges from            0.2             to             0.3 m.                        Aeolian deposits (dune)                  18. Yellowish brown sand (2.5 Y 6/4)          The total thickness ranges between 0.3 and 0.5 m.              The offshore stratigraphy        The boreholes and the trenches        excavated in the western and eastern parts of the Pi        é        gu (Fig. 1 / C / O) modern beach        provide enough data to build a section of the lower part of the local                Quaternary deposits. Table 4 and        figure 5 summarize the organization of the deposits located                under the surface of the        beach.              Table 4:                 Stratigraphical facies identified in        the offshore section.        Tableau 4 : Faciès stratigraphiques          identifiés dans la section sous l’estran.                                    Figure 5: Pi        é        gu Offshore section.                Figure 5 : Section de Piégu sous        l’estran.                             The signification of the ornaments is        the same as for Figure 4. The description of the lithology of the        various layers is given in Table 4.        La signification des symboles est          la même que pour la Figure 4. La description de la lithologie des          différentes couches est donnée dans le Tableau 4.      Marine deposits                  1. Red-orange and dark brown sand (7.5          YR 5/8) with pebbles at the lower boundary with undetermined          fragments of mollusc shells. The excavated layer is about 1 m in          thickness (Samples 1, 11, 14 and 15).              Erosional levelMarine      deposits (coastal deposits covered by water)                              2.             Grey clay (10 YR 7/1) with                        molluscs (sample 12)            .             The thickness is up to 0.2            m.                                                3. Beige-yellow (10 YR 7/6) sand            with molluscs and shell detritus (samples 13 and 3)            .             The thickness is up to 0.4            m.                                                4.             Grey sandy clay (10 YR 6/1)                        with mollusc shell detritus            (sample 2)            .             The thickness is up to 0.7            m.                                                5.             Grey clay (10 YR 6/1)             with small-undetermined mollusc            shell fragments (sample 4)            .             The thickness is up to 0.2            m.                                                6. Brown-reddish (5 YR 5/4) sand            with mollusc shell detritus (sample 5)            .             The             thickness is up to 0.3            m.                                                7. Grey clay (10 YR 6/1)            with             molluscs and shell detritus            (sample 6)            .             The thickness is up to 0.8            m.                        Erosional levelMarine deposits                  8. Loamy pedogenized gravel with          small-undetermined fragments of mollusc shells (sample 7). The          thickness is of 0.8 m.                          9. Sand. The thickness is up to 0.2 m.                                    10. Grey clay (10 YR 6/1) containing          artifacts. The thickness is up to 0.2 m.                          11. Yellowish-red sand (5 YR 5/6). The          thickness is of 0.3 m.                          12. Grey clay (10 YR 6/1). The          thickness is of 0.3 m.              Erosional levelMarine deposits                  13. Yellowish brown sand (10 YR 5/6).          The thickness is of 0.3 m.              The stratigraphical attributions        The possible stratigraphic subdivision        and their correlation with the marine isotope stages given for the        different layers recognized in the Pi        é        gu area are based on the previous        observations made by Monnier (1973), Monnier         et al        . (1985) and Monnier &#38; Hallégouët        (1997a).         This stratigraphy is supported by        the existence of equivalent facies known in various neighbouring sites        located in the same Pléneuf-Val-André area (Laforge, 2012) and in the        Eastern part of the Normano-Breton gulf where Pleistocene deposits        have been dated (Bahain         et al        ., 2012).              – In the Western section we          identified the following layers:        Lower part of         Nantois         Formation (Layers A – C): Middle        PleistoceneUpper part of         Nantois Formation (        Layers D –         J        ):         Middle Pleistocene                Lower part of La Haute-Ville Formation        (Layers K &#38; H): Upper PleistocenePort-Morvan        Formation (Layer I): Upper        PleistoceneSables-d’Or-les-Pins Formation (Layer        L): Upper Pleistocene        Layers N &#38; M: Holocene              – In the Eastern section we          identify the following layers:        Nantois Formation (        Layers 1-10):         Middle        PleistoceneLower part of La Haute-Ville Formation        (Layers 11 &#38; 12): Upper Pleistocene        Upper part of La Haute-Ville Formation        (Layers 13 &#38; 14): Upper PleistocenePort-Morvan        Formation (Layers 15 &#38; 16):         Upper        Pleistocene        Layer 17: Middle        Holocene?Layer 18: Upper Holocene              – In the offshore section we          identify the following layers:         Middle part of Nantois Formation        (        Layer 1):         Middle        Pleistocene        Upper part of Nantois Formation        (        Layers 2-7):         Middle        PleistoceneLower part         of         La Haute Ville Formation         (        Layers 8-12):         Upper        Pleistocene                Layer 13: Upper Holocene              The correlation between the          investigated sections is given in figure 6. Their attribution to the          General Quaternary subdivisions and to the Marine Isotope Stages is          shown in Table 1.              Figure 6: Correlations between the        investigated sections and possible attribution to the regional (A) and        general (B) stratigraphical schemes used in this        paper.        Figure 6 : Corrélations entre les          sections etudiées et attribution stratigraphiques possible aux          schemas régional (A) et general (B) utilisés dans cette          note.                    W – Western onshore excavation;      E – Eastern onshore excavation; O – Offshore boreholes and trenches. For      the lithological and the geochronological data as well as for the      description of the layers see Figs 3-5 and Table      6.W – excavation Ouest à terre; E –          excavation Est à terre; O – sondages et tranchées sous l’estran. En          ce qui concerne les données lithologiques et          géochronologiques et les descriptions des différentes couches se          reporter aux figures 3 ă 5 et au tableau 6.Recent malacological data        A total of 4298 mollusc shells        belonging to 40 species were identified in the deposits                 previously attributed to the Middle        and Upper Pleistocene and to the Holocene (Table 5). The mollusc        shells were collected in the         Nantois Formation considered to be        Middle Pleistocene in age, in La Haute-Ville         and Port-Morvan         Formations of Upper Pleistocene age        and in the Middle? Holocene deposits.         The marine molluscs shells found in        the continental deposits have been considered as the result of a        redeposition of previous marine sediment or transported by winds        blowing towards the coast. It is difficult to determine these shells        because they are fragmented in small pieces or correspond to juvenile        individuals badly preserved which could lead to numbering errors. In        our calculations we did not take these         species into account and focused only        on terrestrial species because they permit a better         understanding of the evolution of the        palaeoenvironment for a given period.              Table 5:                 Summary of the distribution of the        molluscs found in the Western, Eastern and Offshore        excavations.        Tableau 5 : Résumé de la          distribution des mollusques trouvés dans les excavations Ouest, Est          et sous l’estran.                            f – shell detritus not calculated as          a number of individuals; n – numerous; j – juvenile shell; r –          redeposited; 82W, 36E, BW, 1C – numbers of samples, location shown          on Figures 2-4, W – Western section, E – eastern section, C –          offshore trenches; J, B, G, K, H – layers of the Western section.          Stratigraphical subdivisions: A – Hoogeveen Interstadial, MIS 9; B –          Bantega interstadial, MIS 7; C – Drenthe glaciation, Cold Interval          with permafrost, MIS 6; D – Eemian, MIS 5e; E – Lower Weichselian,          MIS 5 a-d; F – Lower Weichselian, MIS 4; G – Middle Weichselian, MIS          3; H – Holocene, MIS 1.        f – fragments de coquilles non          comptés comme des individus entiers; n – nombreuses; j – coquilles          de juvéniles; r – redéposées; 82W, 36E, BW, 1C – nombres          d’échantillons, localisation montrée sur les Figures 2-4, W –          Section Ouest, E – Section Est, C – Tranchées sous l’estran; J, B,          G, K, H – Couches de la section Ouest. Subdivisions          stratigraphiques: A – Interstade d’Hoogeveen, MIS 9; B – Interstade          de Bantega, MIS 7; C – Glaciation de Drenthe, Episode froid avec          permafrost, MIS 6; D – Eémien, MIS 5e; E – Weichsélien inférieur,          MIS 5 a-d; F – Weichsélien inférieur, MIS 4; G – Weichsélien moyen,          MIS 3; H – Holocène, MIS 1.      Malacological study      results and interpretationThe Nantois offshore and western aeolian      formations        Mollusc shells were found in the        marine deposits incorporated in the Nantois Formation of the Western        section (attributed to the Hoogeveen Interstadial,         MIS 9), in the marine deposits of the        Offshore section (correlated with the Bantega Interstadial, MIS 7-10)        and in the aeolian deposits of the Western section (formed during the        Drenthe glaciation and Interval with         permafrost, MIS 6).              - In the lower part of the Nantois        Formation we only discovered fragments of marine bivalve        s         in the         coastal deposits of the Western        section (correlated with the         Hoogeveen Interstadial )        (        MIS 9). Two fragments of the        terrestrial molluscs discovered in the same deposits were very likely        redeposited from the cliff.              - The middle part of the Nantois        Formation was also poor in mollusc fossils. Rare fragments of        terrestrial Succineidae and         Pupilla         sp. as well as marine         Peringia         sp. and         Rissoa lilacina         C. Récluz, 1843         were determined in the deposits          attributed to the         Bantega interstadial (MIS        7-10).              The best mollusc remnants were        discovered in the calcareous dune which accumulated during the first        half of the Drenthe glaciation, Cold Interval with permafrost (MIS 6)        (fig. 7). This formation is characterized by the existence of        terrestrial and aquatic molluscs which complete the list previously        given by Keen (Keen         et al.         1997).         Succinella oblonga         (Draparnaud, 1801)        ,         Pupilla muscorum         (        Linnaeus, 1758        )         and         Trichia hispida         (        Linnaeus, 1758        )         dominate in this association.                Carychium minimum         O. Müller, 1774,         Cochlicopa         sp. (cf.         Cochlicopa                 lubrica         (O. Müller, 1774)),         Vertigo pygmaea         (Draparnaud, 1801),         Punctum pygmaeum         (Draparnaud, 1801),         Vitrea crystallina         (O. Müller, 1774) and         Cernuella virgata         (da Costa, 1778)         are less abundant.         Oxyloma elegans         (Risso, 1826),         Vallonia         sp.,         Vertigo antivertigo         (Draparnaud, 1801),         Vertigo alpestris         Alder, 1838,         Clausilia bidentata         (Ström, 1765)         and         Helicella         sp. are rare (Table 5). We had some        doubts during determinations of the Hydromiidae species because these        shells are represented by juvenile individuals and are badly        preserved. Nevertheless we tried to separate (with some question mark)        this mollusc family into three species –         T. hispida,         C. virgata                 and         Helicella         sp.        ;                 two of them are shown in Table 6.                T. hispida         has an open umbilicus at the entrance        and become narrow and cylindrical in the deep.         C.         virgata         has variable umbilicus shapes but is        always open;         shell         has a light brown band at the                periphery of the whorl (Animal        base).      Figure 7: Middle Pleistocene (MIS 6)      terrestrial gastropods of Piégu, Brittany,      France.Figure 7 : Gastéropodes du          Pléistocène moyen de Piégu, Bretagne, France.                              1 –         Vitrea crystallina         (Müll.), IG № 228/3454/4 (sample        80W); 2 –         Vallonia                 pulchella         (Müll.), IG № 228/3422/1 (sample        13С); 3 –         Punctum pygmaeum         (Drap.), IG № 228/3492/5 (sample JW);        4 –         Carychium minimum         Müll., IG № 228/3390/5 (sample        81/80W); 5 –         Vertigo pygmaea         (Drap.), IG № 228/3454/3 (sample        80W); 6 –         Vertigo                 antivertigo         (Drap.), IG № 228/3493/8 (sample JW);        7 –         Cochlicopa         sp., IG № 228/3390/7 (sample 81/80W);        8 –         Pupilla muscorum         (L.), IG № 228/3454/2 (sample 80W); 9        –         Pupilla muscorum         (L.), IG № 228/3493/6 (sample JW); 10        – Limacidaea, IG № 228/3436/2 (sample 38E); 11 –         Trichia hispida         (L.), IG № 228/3493/10 (sample JW); 12        –         Cernuella virgata         (Da Costa), IG № 228/3493/11 (sample        JW); 13 –         Succinella oblonga         (Drap.), IG № 228/3390/6 (sample 80W);        a – apertural view; b – lateral view (top right); c – abapertural view        (view from the opposite side of the aperture); d – apical view; e –        umbilical view or for                 Limacidae – basal view (view from the        opposite apical side); W – samples of the Western section; C – sample        of the offshore section. Drenthe glaciation, Cold Interval with        permafrost – samples 80W, 38E; Drenthe glaciation – JW, 81/80W, 38E,        13С.        1 – Vitrea crystallina (Müll.), IG          № 228/3454/4 (échantillon 80W); 2 – Vallonia pulchella (Müll.), IG №          228/3422/1 (échantillon 13С); 3 – Punctum pygmaeum (Drap.), IG №          228/3492/5 (échantillon JW); 4 – Carychium minimum Müll., IG №          228/3390/5 (échantillon 81/80W); 5 – Vertigo pygmaea (Drap.), IG №          228/3454/3 (sample 80W); 6 – Vertigo antivertigo (Drap.), IG №          228/3493/8 (échantillon JW); 7 – Cochlicopa sp., IG № 228/3390/7          (échantillon 81/80W); 8 – Pupilla muscorum (L.), IG № 228/3454/2          (échantillon 80W); 9 – Pupilla muscorum (L.), IG № 228/3493/6          (échantillon JW); 10 – Limacidaea, IG № 228/3436/2 (échantillon          38E); 11 – Trichia hispida (L.), IG № 228/3493/10 (échantillon JW);          12 – Cernuella virgata (Da Costa), IG № 228/3493/11 (échantillon          JW); 13 – Succinella oblonga (Drap.), IG № 228/3390/6 (échantillon          80W); a – vue de l’ouverture; b – vue latérale (sommet droit); c –          vue du côté opposé de l’ouverture; d – vue apicale; e – vue de          l’ombilic – vue basale (vue du côté opposé de l’extrémité apicale);          W – échantillons de la section Ouest; C – échantillon of the section          sous l’estran. Glaciation de Drenthe, episode froid avec permafrost          – échantillons 80W, 38E; glaciation de Drenthe – JW, 81/80W, 38E,          13С               The molluscs of this association were        classified according to their modern ecological preferences in air        temperature, humidity, and vegetation cover. Most of the species        correspond with mesophilous conditions.         S. oblonga         and         P. muscorum         are cold resistant and eurytherm        species. The classification of the molluscs, according to present-day        humidity rate indicates that most of the species were hygrophilous.        Only four species (        P. muscorum, C. lubrica, V.                pygmaea         and         Helicella         sp.) are mesophilous.         C. virgata        ,         S. oblonga        ,         O. elegans, P. pygmaeum         inhabited wet environments        characterized by sparse vegetation.         C. bidentata, T. hispida, P.        pygmaeum,                 V. alpestris,                 V. antivertigo         and         C. minimum         show a woodland preference. The Piégu        area was, thus, characterized by a relatively cool forest – steppe –        like environment composed of adjacent mosaics of drier and humid        habitats. Numerous fragments of marine molluscs and juvenile shells        evidence their transportation by winds blowing towards the coast.        Freshwater molluscs suggest the existence of small stagnant ponds or        of small creeks.      The La Haute-Ville Formation        In La Haute-Ville Formation, molluscs        were mainly discovered in the marine deposits of the Western section ,        in the eluvial-slope deposits of the Eastern section (correlated with        the Eemian        , MIS 5e) and in the aeolian and slope        deposits of the Eastern section (correlated with the         Lower Weichselian) (        MIS 5 a-d – 4).              For this level we had only some        renmants of the samples at our disposal. This level is characterized        by small detritus of thick marine shells of Cardiidae (including                Acanthocardia         sp.). As indicated in the chapter        dealing with the previous determinations made by         Lauriat-Rage and Brebion (Keen                et al        ., 1997) 19 different species of        marine bivalves and 10 species of gastropods were determined in this        level. These data confirm the existence of a warm climate during the        Eemian.              The aeolian deposits         of the Eastern section         which correspond to the Lower        Weichselian contain shells of terrestrial and marine molluscs. Our        determinations complete the list of species initially proposed by Keen        (Keen         et al        ., 1997).         Helicela itala         (        Linnaeus, 1758        )         is the dominant species        . T.                 hispida        ,         P. muscorum        ,         C. virgata         and         Vallonia costata         (Müller, 1774) are the other        significant species.         Vallonia pulchella         (Müller, 1774) is poorly represented;        the other species are rare (Table 5).      According to the modern mollusc climatic      distribution, this complex indicates that the best represented species      are usually found in mesophilous conditions. Few species were cold      resistant.According to the present-day humidity rate      these species preferred a subhygrophilous and mesophilous environment.      The dominating species preferred open semi-dry and warm habitats      (calcareous grasslands, south-exposed slopes covered by grasses and      shrubs but also dunes and sea cliffs). The less abundant species are      typical of woodland and intermediate environments. At that time the area      was characterized by a relatively warm forest – steppe (or grassland) –      like environment composed of adjacent mosaics of drier and humid      habitats.        These data confirm the conclusions of        Keen and show that the climate was still warm at the beginning of the        Early Weichselian.         The presence of juvenile shells of        marine molluscs as well as their fragmentation observed in the aeolian        and slope deposits         of the Eastern section                 can be explained by the influence of        marine winds blowing towards the coast.      The Port-Morvan Formation        In the Port-Morvan Formation shell        detritus were only discovered in the         eluvial-slope deposits of the Eastern        section (correlated with Middle Weichselian, MIS 3).      The Holocene formation        M        olluscs were found in the Middle        Holocene sediments, in the podzolic soil of the Eastern section. They        are represented by numerous terrestrial species         (fig. 8)        .         C. virgata         and         P. muscorum         are the dominant species.         V. costata         and         Cochlicella acuta         (O. Müller, 1774)                 are the next more significant species.                V. pulchella         and         Lauria cylindracea         (Da Costa, 1778) are present.                Vitrina pellucida         (Müller, 1774),         Oxychilus draparnaudi         (Beck, 1837),         Truncatellina cylindrica         (Férrusac, 1807), and         C.                 bidentata         are rare (Table 5).         Cecilioides acicula         (Müller, 1774) is a modern burrowing        subterranean species. According to the modern mollusc climatic        distribution this malaco-complex is partly characterized by species        usually found in         mesophilous conditions. In general,        the species of this complex show preference for mesophilous or        subhygrophilous humidity. The highest percentage of species preferred        an intermediate habitat. Fewer species are characteristics of open or        woodlands environments.         C.                 bidentata         lives under tree barks or in cracks        in shady places and may support the existence of isolated trees or of        small forests.         V. costata        ,         V. pulchella        ,         T. cylindrica        ,         V. pellucida         are found in various ecological        environments and were able to live in forests as well as in open        areas. These data suggest the existence of open landscapes covered by        grasses with isolated bushes and small forests. Small marine shells of                Peringia ulvae         (Pennant, 1774),         Tricolia pullus                 (        Linnaeus, 1758        )         and other marine shell detritus were        transported by winds during storms towards the adjacent cliff        area.      Figure 8: Holocene (MIS 1) terrestrial      gastropods of Piégu, Brittany, France (sample      17E).Figure 8 : gastéropodes terrestres          de l’Holocène (MIS 1) de Piégu, Bretagne, France (échantillon          17E).                      1 – Vallonia pulchella (Müll.), IG № 228/3397/4; 2      – Vallonia costata (Müll.),      IG № 228/3397/3; 3 – Lauria      cylindracea (Da Costa), IG № 228/3397/2; 4 – Pupilla muscorum (L.), IG №      228/3397/5; 5 – Truncatellina      cylindrica (Fer.), IG № 228/3397/6; 6 – Clausilia bidentata (Ström), IG №      228/3397/7; 7 – Cochlicella acuta      (Müll.), IG № 228/3397/11; 8 – ?Oxychilus sp., IG № 228/3397/9; 9 –      Cecilioides acicula      (Müll.), IG № 228/3397/8; 10 – Vitrina pellucida (Müll.), IG №      228/3397/10; 11 – Cernuella      virgata (Da Costa), IG № 228/3397/12; a – apertural view; b      – lateral view (top right); c – abapertural view (view from the opposite      side of the aperture); d – apical view; e – umbilical view; 17E – sample      17 of the Eastern section.1 – Vallonia pulchella (Müll.), IG          № 228/3397/4; 2 – Vallonia costata (Müll.), IG № 228/3397/3; 3 –          Lauria cylindracea (Da Costa), IG № 228/3397/2; 4 –          Pupilla muscorum (L.), IG № 228/3397/5; 5 – Truncatellina cylindrica          (Fer.), IG № 228/3397/6; 6 – Clausilia bidentata (Ström), IG №          228/3397/7; 7 – Cochlicella acuta (Müll.), IG № 228/3397/11; 8 –          ?Oxychilus sp., IG № 228/3397/9; 9 – Cecilioides acicula (Müll.), IG          № 228/3397/8; 10 – Vitrina pellucida (Müll.), IG № 228/3397/10; 11 –          Cernuella virgata (Da Costa), IG № 228/3397/12; a – vue de          l’ouverture; b – vue latérale (sommet droit); c – vue du côté opposé          de l’ouverture; d – vue apicale; e – vue de l’ombilic; 17E –          échantillon 17 de la section Est.General palaeoenvironmental      interpretationWe will separate here, the results      and the interpretations related with the Western onshore cliff studied      for archaeology where a continuous observation was possible from those,      more discontinuous and randomly distributed, which were used to build      the Eastern and Offshore sections.The cliffThe hardcore landslides which hide      the initial basement cliff previously cut by the sea, are usually not      cemented by any matrix save in some places where the aeolian sand      deposited between the fragmented rocks. This sandy sediment was probably      deposited after sliding along the slope or by infiltration in the      “head”. Loams also inject by place small gelifracted beds which      developed on top of the upper debris accumulation. They correspond with      a period when the cliff was more or less stabilized. The big-size blocks      reworking and overlapping this formation display a series of slabs      resting at right angle respect with the surface. The underlying rocks      are squeezed together and oriented in a parallel way respect to the      surface (generally dipping between 40 to 50°) (fig. 2). This layer is      characterized by a poorly developed stratification of the material and      the variation in size of the debris may reflect small climatic      variations (Ozouf, 1987). Some larger blocks (up to 1.5 m in length) are      sometimes inter-bedded in this layer. Gelifraction and gravity represent      here the most important phenomena. The microdiorite outcrop which      generated this rocky landslide is very alterated and fragmented. The      largest part of the 2000 cubic meters of debris which were produced      here, resulted mainly from gelifraction. The orientation of the cliff,      open towards the south, probably favored the successive      freezing-defreezing processes. However, it is now known that a very cold      climate is not necessary to generate such a big amount of fragmented      rocks. In our case it is almost certain that the fragmentation was      mainly ruled by a very important moisture (Ozouf, 1987).Taken as a whole the evolution of the      outcrop during the Middle – Late Pleistocene and Holocene can be      described as follow:Middle PleistoceneDuring a first transgressive episode      responsible for the deposition of the lower part of the Nantois      Formation (Hoogeveen Interstadial, MIS      9) the sea completely cleaned out the foot of the cliff and      removed the previous deposits. Abrasion processes were active and it is      possible that the reentrant of the cliff favored the digging of a cave      at that time. After the regression of the sea this shelf, covered by      boulders (the B layer), was buried under a rocky landslide (the C layer)      corresponding also to the lower      part of the Nantois Formation (Cold interval, MIS 8). This      organization evidences the existence of the first interglacial / glacial      cycle.Later, during the Bantega interstadial (Middle part of the Nantois      Formation, MIS 7) the sea partly eroded the previous      deposits although it did not clean all of them. The traces of this      transgression are now represented by a boulder bar (the layer D) which      delivered an Acheulean biface (first human occupation). At the beginning      of the following regression the wind created a sand dune (the layer E).      The deposits of layer E are contemporaneous with the second human      occupation (during the Middle      Palaeolithic) located at the foot of the cliff (the layer      F).This area was then, covered by the upper      rocky landslide (the layer G), during the Cold Interval characterized by      the permafrost and the Drenthe glaciation (MIS 6). It corresponds      with the Upper part of the Nantois Formation.      Layer G is interpreted as a remnant of a butchery station (showing      numerous mammal bones) which was previously located at the top of the      cliff and which collapsed down to the foot of the slope. We don’t know      if the remnants of the butchery witness the existence of a third human      occupation or if they are contemporaneous with the second occupation.      Mammal fauna was found only in the Western part of      the site. In the Western      excavation, mammal bones of      Cervus sp., Bos primigenius Bojanus, Equus      sp., Canis      lupus      L., Dicerorhinus      hemitoechus (Falconer), Capreolus      sp., Sus scrofa L.,      Megaloceros      sp., Panthera      leo spelaea      Goldfuss (?) have been found      in the colluvium of layer 6/G. Remnants of      Cervus      sp. are numerous and      represent 85% of the total bones (August et al.,      2005). Large mammals indicate a forest environment (Auguste      et al., 2005). The small mammals (Arvicola terrestris Linnaeus, 1758) inhabited the banks of water reservoirs, swamps and      wet meadows. These species suggest a Middle Pleistocene age for this      layer.        This period was followed by the        formation of a new sand dune (the layer J). This dune displays        cross-bedding stratifications with coarser levels richer in        continental gastropods. After the malacological study it appears that        this period is characterized by species suggesting a relatively cool        forest – steppe – like environment composed of adjacent mosaics of        drier and humid habitats. The dune seems to correspond to a        “pre-loessic” evolution, that is to say that it was probably deposited        at the beginning of a “loessic cycle”. It is likely that the loess        which probably existed above this formation disappeared later. A        complete loessic cycle can be found for example in the adjacent site        of Nantois (Monnier         et al.,         1997b) where both types of deposits        still exist.      So far as the marine mollusc shells are      concerned, the existence of many broken shell pieces suggests that they      were transported by strong winds.The D to J ensemble represents, thus, a      second interglacial / glacial cycle.Upper PleistoceneA third marine transgression corresponding      to the Eemian Interglacial (lower part of La Haute-Ville Formation, MIS      5e) produced a new shelly sand bar (the layer H) at the foot of a cliff      cut in the Pleistocene deposits. The retreat of the sea was      contemporaneous with the formation of a soil on top of the cliff (the      layer K).During the Early Weichselian (upper part      of La Haute-Ville Formation) the dune developed on the beach (the      Eastern site). Then the slope was buried again during the deposition of      the Weichselian formation (Port-Morvan and Sables-d’Or-les-Pins      formations) (MIS 2 &#38; 3) under a rocky landslide (the layer I) and      sandy loams (the layer L). The layers H, K, I and L represent      consequently a third interglacial / glacial cycle.        In the H beach (Eemian Interstadial,        MIS 5e) a rich fauna of gastropods, bivalves and foraminifers was        found. The malacological study (see Lauriat-Rage and Brebion lists in        Keen         et al        ., 1997) was twinned with the study of        4 drill holes made in the fossil beach.              Most of gastropods were living on        rocky outcrops save         Buccinum undatum                 (        Linnaeus, 1758        )         and         Nassarius (        Hinia) reticulates                 (        Linnaeus, 1758        )         which are usually found on sandy-loamy        surfaces.         Patella, Monodonta, Littorina,        Nucella         and maybe         Myosotella         are typical of tidal zone        associations. Nowadays, this association is well known along the        French Atlantic shores. Only         Astraea,         which usally does not extend north of        Biscay Bay, is characteristic of warmer zone. We observe, thus, a        meridional influence in these species which is not easy to        characterize because of the few samples and the particular sedimentary        facies.              During the Upper Pleistocene,        identical associations were found in other places of Western                Europe. In Selsey, in Southern England        seven Franco-Iberic shapes were found mixed with local fauna but        without         Astraea rugosa         (        Linnaeus, 1767        )                 (West         et al        ., 1960; Bates         et al        . 2006).         In Maillezaie in Vendée an association        limited to 2 species was displaying the Mediterranean-like shape                Cerithium vulgatum         Bruguière,                 1792                 (        Lauriat-Rage         et al        ., 1993)        .         At last in Portugal at Cap Espichel        the almost tropical shape         Cymbula nigra         (da Costa, 1771) is known to live        amongst species typical of this area         (        Lauriat-Rage         et al        . 1993)        .         These data                 confirm that a clear warming episode        existed during the late Interglacial which fits with the definition of        the Eemian. This warmer phase was better expressed in the        Mediterranean realm         than in the European Atlantic domain                (        Brebion, 1980; Lauriat-Rage                et al        ., 1993)        .              Amongst the bivalves (which are        characterized by thick shells), the best-represented taxa are                Mytilus         sp        .,         Pecten maximus         (        Linnaeus, 1758        )        , Cardiidae,         Eastonia rugosa         (Helbling, 1779)         and                 Venus verrucosa         (        Linnaeus, 1758)        .                 P. maximus         and         V. verrucosa         are widespread        .         All these species are still living now        and half of them were already known during Miocene time. The other        species developed during the Pliocene save         Macoma balthica         (        Linnaeus, 1758        )         which is of Pleistocene origin.                Glycymeris pilosa         (        Linnaeus, 1758        )        ,         Mytilus galloprovincialis         Lamark,         1819                 and         E. rugosa         belong to a meridional bio-province                (        Lauriat-Rage         et al        ., 1993; Lindner, 2005; Huber, 2010;        Doneddu &#38; Albano, 2012        ).                 G. pilosa         and         E. rugosa         are restricted to the Mediterranean        Sea and adjacent Atlantic Ocean         (        Lauriat-Rage         et al        ., 1993; Lindner, 2005; Animal        base        ).                 M. galloprovincialis         was restricted to the Black Sea,        Mediterranean Sea and later were spreading until England         (        Lindner, 2005; Audibert &#38;        Delemarre, 2009; Animal base        ).                 For all these reasons the mollusc        fauna of layer H is attributed to the Eemian which represents a warm        interglacial period. Those infra-tidal bivalves were living in        slightly different biotopes. Most of them belong to the endofauna and        a smaller part to the epifauna. They accumulated as thanatocenosis in        a tempest bar.              The benthic foraminiferous        associations previously determined by Lefebvre (Keen         et al        ., 1997) (Western site, layer H) show        a mixture of warm and lukewarm species in the studied Eemian        deposits.      After the recent malacological study the      area was characterized by a relatively warm forest – steppe (or      grassland) – like environment composed of adjacent mosaics of drier and      humid habitats during Early Weichselian.Holocene        After Last Glacial time, during the        Early and Middle Holocene, the slope was covered again by a new        landslide (the layer N of the Western section). Modern deposits are        now forming the actual beach (the layer M). This Holocene deposit was        described by Hallégouët         et al        . (1997).      Numerous land gastropods were found in the      eluvial deposits mixed with rock fragments of the Eastern section (layer      17) (Table 5). The continental malacofauna extracted from these deposits      is represented by species which lived in moderately warm and wet climate      and usually preferred open landscapes covered by grasses with isolated      bushes and small forests, warm rocky slopes or dunes. The climate was      moderately wet and warm. It is possible that those deposits belong to      the Middle Holocene.The beachThe sand of the actual beach rests      above an erosional limit which cuts across the remnants of two phases of      deposition (fig. 5).The Upper phase is dipping towards      the Southwest and extends up to the reentrant of the old cliff. This      ensemble lies above a former erosional surface which affects the oldest      known marine formations. The loams and the sands of the lowest ensemble      are well developed in the Eastern part of the beach where they were      preserved. This is why we can still sample the pre-Eemian layers. On the      contrary in the Northwest, the pre-glacial deposits are rare. The rocky      landslide seems to be limited in extension and does not extend      laterally. The only possible correlation which can be suggested between      the Western onshore cliff and the beach, concerns the sandy dune      formation (J) which could be linked with the calcareous sandy layers      located above the lower orange sands found under this beach. Some bones      and artifacts have been sampled at the boundary between these two      formations. In these conditions the loams and the sands of the lower      phase found under the beach would be equivalent to the periglacial      formations which were previously covering the Piégu cliff. If this is correct the sand      injected in the first debris flow of the cliff (the E layer) would be      equivalent to the orange sand of the northern      part of the beach (layer 1, fig. 5).The eroded fossil shelf found front      of the “archaeological” cliff can be extended under the rocky landslide.      There, boulders reworking sometimes prehistoric artifacts fill      palaeo-topographic depressions. South of this palaeo-shelf a second      marine eroded surface displays aeolian sands injecting an old rocky      landslide. Here a second Palaeolithic industry but without “bifaces” has      been found.Discussion        Piégu site is of a great        stratigraphic interest because it is characterized by the local                preservation of very rare Pleistocene        deposits older than MIS 5 and mainly by a palaeo-cliff carved in the        Saalian sediments by the Eemian Sea. This situation is similar to the        organization of La Cotte Saint-Brelade site in Jersey (Callow &#38;        Cornford, 1986). The stratigraphic interpretation of the Piégu        sections is supported by the known stratigraphic successions        established for various neighbouring sites located in the same        Pléneuf-Val-André area (Laforge, 2012) and in the Eastern part of the        Normano-Breton gulf where Pleistocene deposits have been dated (Bahain                et al        ., 2012).              ESR and US-ESR data (table 6) have        been recently obtained on quartz and biological samples from Piégu,        they have been commented in detail in Bahain         et al        . (2012) where the methodology is        discussed. It is important to underline the good agreement observed        between the various results obtained on the different materials. The        second set of measurements confirms generally the former results        except for those previously obtained by Laurent (1993) on quartz        samples. This is due to the new bleaching protocol. This new protocol        permitted to understand that the bleaching rate (and consequently the        ESR age) estimated by Laurent (1993) for the level J of Piégu was        strongly underestimated.              Table 6: List of the various ages        recently obtained on Piégu (after Bahain         et al        .,        2012).        Tableau 6 : Liste des datations          récemment obtenues pour Piégu (d’après Bahain et al.,          2012).                                    The geochronological data now        available for Piégu and for some other neighbouring         Palaeolithic localities of the        Pléneuf-Val-André region show that the last regional        chronostratigraphic framework proposed by Monnier         et al        . (2011) is fully supported by the        new ESR and US-ESR dates.                                    If we take account of these            results and of the available geological and palaeontological data,            it seems reasonable to correlate the layer G of Piégu with the            late MIS 7 or the early MIS 6 (with a mean quadratic age of 193 ±            6 ka obtained on 9 samples) (Bahain             et al            ., 2012). The archaeological and            palaeontological assemblage witnesses the existence of a human            occupation at the top of the cliff during an interglacial stage            (which is in accordance with the biochronological framework of            Northern France; Auguste, 2009). Latter, this material was            reworked in a head deposit when the top of the cliff collapsed            during early stages of the next glacial period.                                                      The correlation between the level            J of Piégu and the neighbouring archaeological layers of Les            Vallées (layer 21) and Nantois (layer 35) proposed by Monnier                        et al            . (2011) is confirmed by the new            dating results. Other ages obtained on “Les Vallées”            archaeological level (Bahain             et al            . 2012), with its cold            palaeontological assemblage, can be correlated with the middle            part of MIS 6 (mean quadratic age of 164 ± 13 ka obtained on 5            samples), that is to say before the glacial maximum attested in            this area by the loess deposits observed in the             sections above the archaeological            layers             (Monnier             et al            ., 2011). It also permits to            observe a good agreement between quartz and bones            data.                                    At last, the marine level H of Piégu          which shows a mean quadratic age of 122 ± 23 ka (based on 2 samples)          can be clearly attributed to the Eemian stage (MIS 5e) after the ESR          and US-ESR dates.              Considering that the lowest marine      deposits observed in the Piégu stratigraphy (layers D and B) corresponds      to two older interglacial stages, it becomes possible to attribute them      in a first approximation to MIS 7 and 9 respectively.In conclusion the ages obtained by ESR and      ESR/U-series methods on the different analysed materials of Piégu      confirm that bones can be used to date late Middle Pleistocene sites.      These results permitted to assign palaeodosimetric ages to several      stages of the regional geological evolution and allowed the dating of      several archaeological evidences, during late MIS 7 – early MIS 6 for      Piégu.ConclusionFor the first time the stratigraphical      subdivisions of the Western and Eastern onshore and Offshore sections      are fully described and illustrated by different figures.The archaeological excavation of Piégu      carried out in 1987 confirmed that the Palaeolithic industry that was      found earlier on the actual beach, was probably older than the last      interglacial (i.e. MIS 5e or Eemian). This age was already supported by      the sedimentological analysis and by the stratigraphy. It has been also      shown that there were three human settlings. One, on an old beach      located at the base of the Pleistocene deposits (probably MIS 9 in age).      Another one located on the fossil beach (probably MIS 7 in age). And a      third one, recognized at the top of the cliff. So far as this occupation      is concerned, we know that the lithic industry and the associated mammal      bones collapsed from the upper member of the section as frost-shattered      screes.The new radiometric ages now published      confirm the chrono-stratigraphy previously suggested. The above      contribution which incorporates many data previously unpublished, some      information poorly known before and the many observations made in the      trenches and boreholes undertaken East and South of the main excavation      contribute to a better understanding of the whole area than the sole      documents extracted from the “archaeological” site alone. The new data      complete and confirm our previous stratigraphical knowledge of the site.      The new malacological data, incorporated together with the previous      determinations, provide, for the first time, a detailed synthesis of the      environmental evolution of Piégu area during the Middle to Late      Pleistocene and Holocene times.At the regional scale, the site of Piégu      is of a major interest from a stratigraphic and archaeological point of      view. It represents one of the very rare sites of westernmost Europe      where calcareous deposits and bone remnants associated with a      Palaeolithic lithic industry are still preserved. Elsewhere, in      Brittany, the acidy of the soil destroyed almost always bones and      mollusc shells. The results are also important if we take account of the      large amount of data collected in the rescue conditions which prevailed      during this survey. They are also highly valuable since neither the      cliff nor the trenches can be now directly observed. Study of this site      brings some light on the first populations of the fare west of Europe      since three different periods of occupation were found.