# From Lagoon to River: Bank Management at the Submerged Late Bronze Age Settlement of La Motte (Agde, France)

Thibault Lachenal

► To cite this version:

Thibault Lachenal. From Lagoon to River: Bank Management at the Submerged Late Bronze Age Settlement of La Motte (Agde, France). Ariane Ballmer; Albert Hafner; Willy Tinner. Prehistoric Wetland Sites of Southern Europe, Springer Nature Switzerland, pp.21-45, 2024, Natural Science in Archaeology, 10.1007/978-3-031-52780-7_2. hal-04788229

HAL Id: hal-04788229

https://hal.science/hal-04788229v1

Submitted on 18 Nov 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# From Lagoon to River: Bank Management at the Submerged Late Bronze Age Settlement of La Motte (Agde, France)

Thibault Lachenal

## Abstract

The La Motte 1 site (Agde), submerged in the bed of the Hérault River, corresponds to a settlement from the end of the Bronze Age initially established on the edge of a lagoon that is now clogged. The site is characterised by more than 500 wooden piles divided into two main groups located on shoals. The use of varied species attests to the exploitation of distinct environments such as Mediterranean mixed oak forests and riparian forests. Moreover, the spatial analysis illustrates the presence of several coherent alignments that use a specific species. The excavation trenches dug support the interpretation thereof as systems for bank maintenance and protection via different techniques: wattle made from the strawberry tree on oak piles, and possible live stakes made of willow. The study of the goods and radiocarbon dating show the successive installation of these systems between the 10th and the beginning of the 8th centuries BC. The goal of the various technical solutions was to protect the areas around the settlement from erosion. Their use must therefore be examined in the light of the changes in their

immediate surroundings, which saw a rise in the sea level coupled with a progressive filling of the delta of the Hérault. This case study thus illustrates the capacity to adapt and the vulnerability of the populations of the Bronze Age in the face of changes in a particularly sensitive environment.

## Keywords

Southern France • Late Bronze Age •
Lagoon • Piles • Wattle • Bank reinforcement

## 2.1 Introduction

Currently submerged in the bed of the Hérault River, the La Motte 1 site was discovered in 2001 during a subaquatic survey. In 2004, a dig revealed a deposit of objects, mostly made of bronze, corresponding to a rich ornament with feminine connotations dating to the eighth century BC (Moyat et al. 2005, 2007; Verger et al. 2007). Although this exceptional discovery was the focus of the work during this dig, the presence of a settlement from the end of the Bronze Age, embodied by wooden piles and numerous remains of a domestic nature, was also brought to light. The context in which this settlement was located remained unclear: low bank of a river, island, or shoal in the riverbed, or even a village built on a lagoon (Moyat et al. 2007, 80)?

<footnote>T. Lachenal (✉)
UMR 5140 Archéologie des Sociétés
Méditerranéennes (ASM), Université Paul-Valéry,
CNRS, MC, Montpellier, France
e-mail: thibault.lachenal@cnrs.fr</footnote>
Likewise, its extent and duration of occupation
were not able to be determined. New subaquatic
excavation campaigns were thus undertaken in
2011, accompanied by a research program on the
palaeoenvironment and the geomorphology of
the territory around Agde from the beginning of
the Holocene<fnref n="1" /> (Gascó et al. 2014; Gascó et al.
2015; Deviller et al. 2019; Lachenal et al. 2020).
These multidisciplinary studies revealed a per-
manent settlement set up on the edge of an
ancient lagoon, with an economy mainly based
on agriculture and livestock (Bouby et al. 2016;
Lespes et al. 2019). Both the lagoon and the al-
luvial plain were exploited, although land
resources seem to be prevalent. Several signs
point to the elevated social status of the group (or
of certain individuals) who occupied the site.
Herd management, which indicates the search for
quality meat, supposes a privileged social envi-
ronment (Lespes et al. 2019). The presence of
several deposits of metal objects, including a rich
ceremonial garment, indicates the same (Verger
et al. 2007; Lachenal 2022a). Metallurgy seems
to have been a dynamic craft activity at the site,
as attested by the presence of several moulds,
which raises the question of the role of the set-
tlement in the production and distribution of
objects made from copper alloy, potentially
manufactured using the copper ore from the
Cabrières district located in the hinterland
(Lachenal 2022b). The location of the site near
the coast and the natural landmark formed by the
Cap d'Agde potentially gave it a strategic posi-
tion in the organisation of exchanges. The
founding of this community does not therefore
seem to be the result of chance. However, such
interface areas between the land and sea, reputed
to be unsanitary, present numerous constraints.
Bronze Age lagoon settlements around the Gulf

of Lion were thus considered for a long time to
be sites occupied temporarily, during the dry
season (Py 1990).

Indeed, adaptation to this environment
required the implementation of specific structures
by the settlement's occupants. Made of wood,
these structures were exceptionally preserved due
to the submersion of the site. Here, we present
the various types of structures identified during
digs, their supposed function, and their
chronology.

## 2.2 From Lagoon to River: Location and Palaeogeography of the Site

The La Motte site is currently located in the bed
of the Hérault River, 5 km from its mouth and a
little more than 500 m north of the modern city
of Agde, in a portion of the river intersected by
the Canal du Midi (Fig. 2.1). The site is located
downstream of a meander formed by the river
where it meets the northern flow of the Mont
Saint-Loup volcanic complex.

The archaeological remains, which appear on
the surface of the river bottom, are located on
shoals preserved from erosion (Fig. 2.2), at a
depth of between 4 and 6 m. It should be noted,
however, that the bottom water level is artifi-
cially raised by 1.83 m by the La Pansière dam,
400 m downstream.

The location of the settlement at La Motte in
potentially very dynamic coastal surroundings
immediately raised the question of the site's
environment and the evolution thereof. A set of
34 boreholes associated with 61 radiocarbon
datings and biological and geochemical analyses
allowed the geomorphological evolution of the
lower Hérault valley from the beginning of the
Holocene to be described (Devillers et al. 2019).
Until 6500 cal BP, the morphology was domi-
nated by waves and retrogradation. During this
phase, successive ephemeral river mouths
formed and were rapidly submerged by the rising
sea level. A progradation phase started after
6500 cal BP. It progressively filled the estuary
with the advance of the ria, and several shallow

<footnote n="1">¹ This program, which is still underway, ran in 2011 and from 2013 to 2015 under the supervision of Jean Gascó (CNRS UMR 5140 ASM), then from 2016 to 2021 under Thibault Lachenal (CNRS UMR 5140 ASM), in collaboration with the association Ibis (Agde). The work was supported by the LabEx ARCHIMEDE via the Investissement d'Avenir program, ANR-11-LABX-0032-01, and the projects DYLITAG (dir. B. Devillers) and SiLÂB (dir. T. Lachenal).</footnote>
<figure><img src="image_2.png" /><figcaption>**Fig. 2.1** Location of the La Motte site in south-eastern France (GIS by T. Lachenal; background BD by ALTI®)</figcaption></figure>

lagoons associated with beach ridges have been distinguished. For the Bronze Age, the high density of information points to a delta morphology with a pronounced fluvial dominance. It appears that the site of La Motte was established on the edge of an ancient lagoon, near the mouth

of the river. During the site's occupation, the fluvial sedimentation dynamics, associated with anthropic waste, led to the filling in of the lagoon before the sediments transported by the river clogged the lower part of the Hérault valley (Devillers et al. 2019). This mosaic of
<figure><img src="image_3.png" /><figcaption>**Fig. 2.2** Map of the features on the bathymetric survey of the La Motte site (GIS T. Lachenal; bathymetry by F. Yung)</figcaption></figure>

environments is illustrated by the palaeoentomological and carpological analyses, which attest to the nearby presence of Mediterranean and riparian forests, the river, and the biotopes found along coastal lagoons, such as *sansouires* (salt marshes) and reedbeds (Bouby et al. 2016, 85–86). The site was thus located in Bronze Age lagoon habitats that are well known along the coast of the Gulf of Lion, in particular around the Étang de l'Or and Étang de Thau (Dedet and Py 1985; Leroy 2010).

## 2.3 The Plan and the Structures

The study of the La Motte site uses two complementary approaches: an extensive overhead survey of all the structures directly visible on the surface and excavation trenches in several key sectors to document the stratigraphy of the site and its evolution. This strategy was adopted in response to the time and cost constraints specific to subaquatic operations.
The La Motte site is characterised by more
than 500 wooden piles divided into two main
groups. The first, to the west and near the right
bank, has a northwest-southeast orientation and
includes more than 200 pieces of architectural
wood. The second, near the left bank to the east,
is more roughly oriented north-south and con-
tains 323 piles (Figs. 2.2 and 2.3). In these two
sectors, located on shoals, the wood was asso-
ciated with remains from domestic activities
(pottery, fauna, grinding goods, etc.), as well as
numerous basalt blocks. The latter very probably
come from the outcrops located farther south,
from the volcanic flow on which the modern city
of Agde is built. Riprap consisting of large
blocks of basalt reaching a width of 50 cm also
borders the remains to the east and to the north.
An excavation trench carried out in sector 1
(Fig. 2.3) revealed, however, that they were
installed after the Bronze Age occupation and
must date to between antiquity and the modern
era.

**2.3.1 The Piles**

The wood identified corresponds for the most
part to vertical elements, piles and stakes, some
of which may have collapsed. The specimens
analysed reveal the use of varied species, which
indicates a diversified exploitation of distinct
environments: Mediterranean mixed oak forest,
alluvial forest (floodplain) and riparian forest
(streambed). Oak (*Quercus* sp.) and elm (*Ulmus*
sp.) are highly dominant, but willow (*Salix*
sp.), holm oak (*Quercus ilex*), alder (*Alnus*
sp.), and ash (*Fraxinus* cf. *angustifolia/ornus*) are also
well represented. The diameters of the wood,
which range from 3 to 20 cm, are for the most
part between 6 and 10 cm (Fig. 2.4). These were
therefore mostly young trees. The piles were
made from whole trunks of green wood, which is
evidenced by the deformation of some pile tips
after their staking and were not debarked. They
seem to reflect a simple exploitation of a forest
environment in which wood was plentiful. The
points of these piles were sharpened to a single or
multiple bevel/s (Lachenal et al. 2020).

**2.3.2 Spatial Distribution of the Species of Wood**

In the sectors in which the anatomic identifica-
tion of the wood was carried out exhaustively, it
is possible to perform a spatial analysis of the
structuring of the site based on the nature of the
wood used (Lachenal et al. 2020).

In sectors 1 and 2 on the left bank, among the
wood that was subject to an anatomical deter-
mination, elm (*Ulmus* sp.) and oaks (*Quercus*
sp. and *Quercus* cf. *coccifera/ilex*) represent the
large majority (Fig. 2.5). Several coherent
arrangements can be distinguished, with a line of
fallen oak specimens to the south that seems to
divide into two branches, which are also present
farther north. One of them is superimposed on an
alignment of elm posts.

In sectors 3 and 4, to the west on the right
bank, there is also a large variety of species, with
ten tree species identified (Fig. 2.6). Three of
them, however, are clearly superior in number:
oak (82 pieces), elm (78 piles), and willow (*Salix*
sp.: 26). The groupings of the wood show several
alignments using a specific species. To the
southwest, a line of piles corresponds for the
most part to specimens made of elm. In parallel,
three alignments of oak piles can also be distin-
guished farther east, towards the middle of the
river. Finally, in the northwest of this sector,
three small sections principally use stakes made
from willow. The coherence of these various
arrangements allows them to be interpreted as
several successive structures. The use of different
wood could thus be explained as the result of the
exploitation of varied environments: deciduous
oak forest, alluvial forest for elm and riparian
forest for willow.

**2.3.3 Interpretation of the Alignments of Piles: Results of the Excavation Trenches**

**2.3.3.1 Sector 2**

An excavation trench passing through squares
D44, D63, D87, and D118 was dug in the
southern part of the line of oak piles of sector 2 in
<figure><img src="image_4.png" /><figcaption>**Fig. 2.3** General mapping of the features of the La Motte site and location of the trial trenches (GIS by T. Lachenal)</figcaption></figure>

order to interpret these alignments of piles
(Fig. 2.3). The dig revealed the presence of
wattle (US 3) inclined to the east (Fig. 2.7b). The
posts supporting it are oak piles on which the
bark has been partially preserved, with irregular,
non-rectilinear shapes between 2 and 2.5 m long

(Fig. 2.7a). They support a lattice of unpruned
strawberry-tree (Arbutus unedo) branches that
are twisted and woven between the piles
(Fig. 2.8). The presence of oysters in a living
position at the tips of the piles suggests that the
base of this structure was underwater when it was
<figure><img src="image_5.png" /><figcaption>**Fig. 2.4** Distribution of the wood species of the piles by diameter class (Xylological analysis by S. Greck)</figcaption></figure>

in use (Fig. 2.7a). This structure can be inter-
preted as a bank reinforcement system. The
incline observed can thus correspond either to the
collapse of the structure or to its installation on
an inclined slope. A level of basalt blocks, some
of which had been colonised by oysters (US 23),
was present at the base of the wattle (Fig. 2.7b).
This corresponds to a deliberate laying of stones
that may also have been used to reinforce the
bank and act as a submerged foundation for the
wattle, according to a mixed solution currently
used in vegetation engineering<fnref n="2" /> (Adam et al.
2008, 152).

The stratigraphy associated with this wattle
features the alternation, under more recently
formed units (US 17, 14), of layers of sandy and
clay loam grey in colour, rich in ceramic goods,
fauna, and shells (US 11–15, 10, 18, 1, 2, 7, 22),
with browner layers very rich in organic matter
but poorer in terms of goods (US 4, 6, 8, 13, 12,
19). All these levels are, just like the wattle,
inclined towards the east. They thus tend to
confirm the presence of a bank in this sector,
located in contact with the protohistoric settle-
ment and the palaeolagoon. The various types of
levels identified can be interpreted as fill of

different origins: waste from the kitchen and
other domestic activities for the levels rich in
goods, and waste from construction phases or
deposits of plants transported by the current for
those rich in organic matter. Either the wattle
arrangement was used to protect the banks from
erosion, or it was deliberately placed as form-
work to hold this fill and reclaim land from the
lagoon, similar to the systems of artificial islands
in the village of Ganvié, located on Lake
Nokoué in Benin (Pétrequin and Pétrequin
1984).

2.3.3.2 Sector 3

In Sector 3, the trench dug in D26 (Gascó et al.
2014, 2015; Lachenal et al. 2020), is located at
the southern end of the alignments of oak piles
identified to the west (Figs. 2.3 and 2.6). The
stratigraphy encountered here also has a marked
incline to the southwest, perpendicular to the
alignments of piles, indicating the presence of a
bank. It consists of heterogeneous levels of
domestic waste (US 11, 12, 13, 17) and others
especially rich in stratified or compacted plant
organic matter (US 2, 3, 4, 6, 8, 9, 18), while
sterile sandy clay layers may have been depos-
ited by episodes of flooding (US 5, 7, 10). In US
15, an arrangement of wattle supported by posts,
partly collapsed, was identified (Fig. 2.9). The
presence of oysters fastened onto its base indi-
cates its installation in partly submerged sur-
roundings. It can be interpreted as wattle

<footnote n="2">² The French term for vegetation engineering, ‘génie végétal’, is defined as the use of live plants, parts thereof, and seeds in order to solve engineering problems in the mechanical fields of protection against erosion and land stabilisation and regeneration (Adam et al. 2008, 43).</footnote>
<figure><img src="image_6.png" /><figcaption>**Fig. 2.5** Interpretation of the distribution plan of pile wood species in sectors 1 and 2 (GIS by T. Lachenal; xylological analysis by S. Greck)</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>**Fig. 2.6** Interpretation of the distribution plan of pile wood species in sectors 3 and 4 (GIS T. Lachenal; xylological analysis by S. Greck)</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>**Fig. 2.7** a Plan of the wattle in the sector 2 excavation (D44–D63–D87–D118). b Stratigraphic section (drawing by F. Laurent, CAD by T. Lachenal)</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>**Fig. 2.8** a, b Strips 2 and 3 of the excavation of the wattle block in the laboratory (photo L. Chabal). c, d Details of the wattle in the excavation (Photo by J.-C. Iché)</figcaption></figure>
<figure><img src="image_10.png" /><figcaption>**Fig. 2.9** a Plan of wattle remains in the trial trench of sector 3 (D26). b Stratigraphic section (drawing by B. Debrand, CAD by J. Gascó)</figcaption></figure>

supporting a bank, having an opposite orientation with respect to that of sector 2, but a similar installation and function.

#### 2.3.3.3 Sector 4

In this sector, a trench was dug in squares C22 and C23, where an alignment of willow piles was
set up (Figs. 2.6 and 2.10a). This is also the zone
in which the deposit of ornamental elements was
discovered. The excavation once again revealed a
stratigraphy strongly inclined towards the
southwest, perpendicularly to the alignment of
piles identified in this sector (Fig. 2.10b). This
sequence is thus also located in a bank area on
the edge of the protohistoric occupation. Here
again, there are anthropic deposits corresponding
to domestic waste or fill (8, 11, 15, 17, 19, 22,
23, 24), levels of accumulation of small plant
debris transported by the current (US 12, 14, 18,
21), and flood episodes marked by pure clay
sediment (1/13). The excavation also uncovered
the piles embedded on the edge of this bank,
which are not associated with wattle here. They
consist of willow and elm with a small diameter,
between 8 and 10 cm, and with the bark pre-
served (Fig. 2.11). The willows have the partic-
ularity of having conserved small branches, and a
fine development of roots was sometimes
observed above their tips, even though their
points were sharpened. It is thus possible to put
forward the hypothesis of these being live stakes,
a technique still in use today for bank stabilisa-
tion. The use of willow is revealing because it is
the preferred species in vegetation engineering
today due to its pioneering nature and its aptitude
for vegetative regeneration (Adam et al. 2008,
p. 97). This species is also particularly resistant
to submersion and flooding; therefore, its use
suggests good knowledge of its ecology on the
part of the site's inhabitants. Another hypothesis
is that the branches were left behind to facilitate
the installation of the piles in the ground.

At the base of this trench, six fallen piles were
discovered, belonging to a first collapsed pal-
isade on sterile lagoon levels (US 25). These
piles still have a part of their bark and have a
sharpened tip, always directed towards the upper
part of the bank (Fig. 2.12). This preoccupation
with reinforcing the banks thus required regular
structural works by the site's occupants. The
presence of oysters and shipworm holes on these
piles indicate a brackish lagoon environment.
The willow piles installed later, however, per-
form better in riverine surroundings. The
sequence thus appears to record the progressive

passage from a lagoon edge to a fluvial envi-
ronment, as also indicated by the geomorpho-
logical studies.

2.3.4 The Question of the Settlement Structures

The alignments of piles can for the most part be
interpreted as systems for bank reinforcement
and maintenance at the centre of which there
was a settlement, as suggested by the levels of
domestic waste identified in the excavations,
which produced a very large amount of goods.
Unfortunately, the part of the site located
between these supposed banks was very highly
eroded, as shown by the bathymetric survey
(Fig. 2.2). A transect of subaquatic boreholes
confirmed the absence of preserved strata in this
part of the river. It is probable that the wattle
systems acted as a framework for the archaeo-
logical layers, in accordance with their initial
goal of bank maintenance, and maintained them
in place. On the contrary, when moving away
from these structures, the levels were washed
away by the action of the river, a phenomenon
marked by the presence of erosional ledges. It is
possible, however, to detect the remains of set-
tlement structures in the immediate vicinity of
the banks. In particular in sector 4, in the
northwest of the site, posts with a large diameter
that are not integrated into the alignments of
piles stand out. They allow the reconstruction of
a structure on load-bearing posts, having a
subrectangular shape and ending in an apse to
the north (Fig. 2.13). A characteristic of this
structure is the use of highly varied types of
wood, whereas the bank structures generally
show a relative homogeneity in the species used.
Other pieces of wood with a large diameter
present in various sectors of the site raise
questions about the presence of other buildings.
However, at present, in the spaces studied, no
other complete and coherent floorplan was dis-
cerned. The presence of settlement structures is,
however, also suggested by the discovery of
wall elements made of daub (Lachenal et al.
2020).
<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /><figcaption>**Fig. 2.10** a Plan of the trial trench in sector 4 (C22–C23). b Stratigraphic section (drawing by A. Sebastia and T. Lachenal, CAD by T. Lachenal)</figcaption></figure>
<figure><img src="image_13.png" /><figcaption>**Fig. 2.11** a View of the piles appearing in the trial trench of sector 4 (C22–C23) during the excavation (photo by J. Montès). b Detail of a branch preserved on a trunk (photo by T. Lachenal). c Willow pile sample (Photo by J.-C. Iché)</figcaption></figure>

## 2.4 Chronology of the Site and of the Structures

In order to determine the absolute chronology of the deposits and structures identified, radiocarbon dating was carried out on certain piles and on material from the excavation trenches. At present, twenty dates are available for the site (Table 2.1). These dates are associated with other chronological information provided by the stratigraphy, the typology of the goods, and dendrochronological synchronisation. As a result, they lend themselves to Bayesian modelling (Bronk Ramsey 2009; Lanos and Dufresne 2012), through which the validity of the periodisation proposed can be verified and the limits and duration of each phase can be suggested. The model was created using the ®ChronoModel software (Lanos and Philippe 2017, 2018). Two types of periodisation were carried out,

sometimes including the same dates, relating on the one hand to the infrastructure and on the other hand to the chronotypological data indicated by the ceramic goods (Figs. 2.14 and 2.15). The information on stratigraphic anteriority and posteriority are indicated by arrows (from the oldest to the most recent). Certain piles were also synchronised by dendrochonological analysis (Lachenal et al. 2020). Thus, piles 215 and 254 were shown to be contemporary. Pile 23, however, was cut down after pile 318, which was installed at the same time as pile 315, during the construction of the wattle in sector 2. This structure is located in the stratigraphy between US 2 and 12 in the excavation trench dug in this sector.

Here, we have distinguished a phase prior to the installation of the wattle in sectors 2 and 3, a phase corresponding to this installation, and a later phase. Two other periods correspond to the installation of the two levels of piles and of
<figure><img src="image_14.png" /><figcaption>**Fig. 2.12** Views and plan of the piles collapsed at the base of the trial trench of sector 4 (photo by T. Lachenal and J.-C. Iché; drawings and CAD by T. Lachenal)</figcaption></figure>

willow stakes uncovered in the excavation trench of sector 4 (Figs. 2.14 and 2.15). This analysis shows that the collapsed palisade in this zone dates to the 10th century BC (Fig. 2.16). The associated goods correspond to the Late Bronze Age IIIA of the regional chronology (Dedet 2014), which can be correlated with the classic north-alpine Hallstatt B1-period (David-Elbiali and Dunning 2005). These corpora are characterised by an abundance of convex, more rarely carinate, bowls and dishes, frequently decorated

with patterns incised with a bifid comb with blunt teeth (Fig. 2.17, No. 1–4, 6, 9–10). The large jars with a neck sometimes underlined with a fingertip-impressed band (Fig. 2.17, No. 8), or with a cylindrical neck decorated with fluting and a rim, are also characteristic of this period (Fig. 2.17, No. 13).

Later, the installation of the wattle in sectors 2 and 3 would have been carried out at the end of the 10th century or at the beginning of the 9th century BC (Fig. 2.16). The levels preceding the
<figure><img src="image_15.png" /><figcaption>Fig. 2.13 Plan of a possible building identified in sector 4 (GIS by T. Lachenal; xylological analysis by S. Greck)</figcaption></figure>
<table><caption>**Table 2.1** Radiocarbon dates of the La Motte site</caption><thead><tr><th>Sample</th><th>Material</th><th>Lab. code</th><th>Age BP</th><th>±</th><th>Cal BC (Intcal20)</th><th>Phase: chronotypology</th><th>Phase: bank protection</th><th>Phase: dendronchronology</th></tr></thead><tbody><tr><td>C22 US24 Pile 673</td><td>Wood (pile)</td><td>Poz-143291</td><td>2790</td><td>30</td><td><b>1011-891 (83%)</b> 879-835 (12%)</td><td>BF IIIa</td><td> Collapsed fence</td><td></td></tr><tr><td>US105.17</td><td>Wood (branch)</td><td>Poz-129419</td><td>2795</td><td>30</td><td>1040-1036 (1%) <b>1013-893 (86%)</b> 877-836 (9%)</td><td>BF IIIb early</td><td></td><td></td></tr><tr><td>C22 US 22</td><td>Wood (branch)</td><td>Poz-129417</td><td>2730</td><td>30</td><td><b>926-809 (95%)</b></td><td>BF IIIb early</td><td></td><td></td></tr><tr><td>D26 US 16</td><td>Wood (branch)</td><td>Ly-11446</td><td>2710</td><td>30</td><td><b>909-807 (95%)</b></td><td>BF IIIb early</td><td> Before wattle</td><td></td></tr><tr><td>D87 US 23</td><td>Carbonised residue</td><td>Poz-96358</td><td>2700</td><td>35</td><td><b>911-803 (95%)</b></td><td>BF IIIb early</td><td> Before wattle</td><td></td></tr><tr><td>D26 US 4</td><td><i>Triticum dicoccum</i></td><td>Ly-9038</td><td>2765</td><td>30</td><td><b>994-830 (95%)</b></td><td>BF IIIb late</td><td> After wattle</td><td></td></tr><tr><td>US105.11</td><td>Wood (Mould tenon)</td><td>Poz-129413</td><td>2710</td><td>30</td><td><b>909-807 (95%)</b></td><td>BF IIIb late</td><td></td><td></td></tr><tr><td>D26 US 11</td><td><i>Triticum dicoccum</i></td><td>Ly-9039</td><td>2705</td><td>30</td><td><b>906-806 (95%)</b></td><td>BF IIIb late</td><td> After wattle</td><td></td></tr><tr><td>D26 US 13</td><td>Wood (branch)</td><td>Ly-11444</td><td>2700</td><td>30</td><td><b>903-805 (95%)</b></td><td>BF IIIb late</td><td> After wattle</td><td></td></tr><tr><td>D87 US12</td><td>Charcoal (wood branch)</td><td>Poz-96359</td><td>2690</td><td>35</td><td><b>911-803 (95%)</b></td><td>BF IIIb late</td><td> After wattle</td><td></td></tr><tr><td>C22 US19</td><td>Wood (branch)</td><td>Poz-111143</td><td>2655</td><td>35</td><td>898-857 (19%) <b>847-785 (76%)</b> 783-779 (1%)</td><td>BF IIIb late</td><td></td><td></td></tr><tr><td>Pile 113</td><td>Wood of <i>Salix</i> sp. (last rings)</td><td>Poz-96228</td><td>2605</td><td>35</td><td><b>819-761 (95%)</b></td><td>Bronze/Iron transition</td><td>Willow piles</td><td></td></tr><tr><td>C23 US15</td><td>Wood (branch)</td><td>Poz-96229</td><td>2555</td><td>30</td><td><b>800-748 (95%)</b></td><td>Bronze/Iron transition</td><td></td><td></td></tr><tr><td>C23 US13</td><td>Wood (branch)</td><td>Poz-96360</td><td>2525</td><td>35</td><td><b>791-718 (92%)</b> 707-700 (20%)</td><td>Bronze/Iron transition</td><td></td><td></td></tr><tr><td>US105.03</td><td>Wood (board)</td><td>Poz-129414</td><td>2510</td><td>30</td><td>785-782 (1%) <b>779-716 (88%)</b> 709-700 (6%)</td><td>Bronze/Iron transition</td><td></td><td></td></tr><tr><td>Pile 215</td><td>Wood of <i>Quercus</i> sp. (last rings)</td><td>Ly-11448</td><td>2780</td><td>30</td><td><b>1006-889 (76%)</b> 881-834 (20%)</td><td></td><td>Synchro 1</td><td></td></tr><tr><td>D26 US 15 Pile 257</td><td>Wood of <i>Quercus</i> sp. (last rings)</td><td>Ly-11443</td><td>2730</td><td>30</td><td><b>926-809 (95%)</b></td><td></td><td> Wattle</td><td></td></tr><tr><td>Pile 315</td><td>Wood of <i>Quercus</i> sp. (last rings)</td><td>Ly-11445</td><td>2710</td><td>30</td><td>978-948 (8%) <b>936-817 (88%)</b></td><td></td><td> Wattle</td><td></td></tr><tr><td>Pile 254</td><td>Wood of <i>Quercus</i> sp. (last rings)</td><td>Ly-11447</td><td>2695</td><td>30</td><td><b>901-804 (95%)</b></td><td></td><td></td><td>Synchro 1</td></tr><tr><td>Pile 23</td><td>Wood of <i>Quercus</i> sp. (last rings)</td><td>ARC2445</td><td>2620</td><td>45</td><td>896-867 (7%) <b>839-755 (88%)</b></td><td></td><td></td><td>Synchro 2</td></tr></tbody></table>

BF bronze final (Late Bronze Age). Calibration made with ©ChronoModel using the IntCal20 curve (Reimer et al. 2020). The highest probabilities are highlighted in bold
<figure><img src="image_16.png" /><figcaption>**Fig. 2.14** Chronological modelling based on events dated by radiocarbon (®ChronoModel)</figcaption></figure>

installation of these structures contained ceramic
goods from the beginning of the Mailhac I style
of the Late Bronze Age IIIB (Guilaine 1972).
This style saw the appearance of rectilinear
beakers (Fig. 2.17, No. 21) and cups with inter-
nal incised decoration (Fig. 2.17, No. 16). The
decoration was still most often geometric, in the
form of meanders or broken lines (Fig. 2.17,
No. 21–24). This stage could correspond to the
Hallstatt B2-period.

The strata covering the wattle systems date to the
second half of the 9th century BC and are possibly
contemporary to the Hallstatt B3-period (Fig. 2.16).
The associated goods feature the appearance of
more complex decoration, whether figurative,
zoomorphic, or anthropomorphic (Fig. 2.18).

Finally, the levels uncovered in sector 4
together with the alignment of willow piles
would illustrate the beginning of the 8th century
BC (Fig. 2.16). This period corresponds to the
Phases

<figure><img src="image_17.png" /><figcaption>Fig. 2.15 Chronological model of event phases (©ChronoModel)</figcaption></figure>

phase of transition between the Bronze Age and the Iron Age defined regionally (Janin 1992), contemporary to the beginning of the Hallstatt C-period in continental Europe. This period saw a continuation of the Mailhac I style, together with the appearance of new forms such as low sinuous carinated bowls (Fig. 2.18, No. 12–14). The latter are characteristic of the 8th century BC in the necropolises of Languedoc (Janin 1992; Taffanel and Janin 1998).

## 2.5 Conclusion

Deliberately settled at the interface between two environments, lagoon and alluvial plain, the occupants of the La Motte site had to carry out works in order to protect their settlement for at least two centuries (Fig. 2.19). The excavation trenches dug in three sectors of the site provide information on the implementation of the

alignments of piles revealed by the spatial analysis while taking into account the xylological determination. They all point to systems for bank maintenance and protection via different techniques: simple wooden piles, strawberry-tree wattle supported by oak posts, and possible live willow stakes. This implies a comprehension of the natural functioning of the ecosystems, with the selection and implementation of species of wood and techniques suitable for the management and restoration of the area bordering the lagoon. The occupants of the site sought long-term solutions capable of protecting their settlement and apparently tested several methods. The various parallel alignments identified could thus correspond to successive works, as the domestic waste created near the homes allowed land to be reclaimed from the lagoon. Their goal appears to have been to protect the area around the settlement from erosion. Their implementation must thus be viewed in the light of the
<figure><img src="image_18.png" /><figcaption>**Fig. 2.16** Histograms of the phases modelling made by using ®ChronoModel. MAP, Modes a posteriori of event start and end. HPD, Highest Probability Density region at 95% of event start, end and duration (Author)</figcaption></figure>

geomorphological evolution of the surroundings, which involved a rise in the sea level coupled with a progressive filling of the Hérault delta. The sedimentological studies reveal an increase in the influence of the river during the last phase of occupation of the site, which was dated to the beginning of the 8th century BC. The abandonment of the settlement could thus be connected to an aggradation of the river. This phenomenon must have destabilised the surroundings in which the site's occupants lived, with an increase in floods that threatened the settlement or the beginning of a filling of the lagoon to which it

was connected. The settlement potentially moved onto the basalt relief located 500 m downstream, where the modern city of Agde is situated. Indeed, it was in this sector that the Peyrou necropolis, dating to the 7th century BC, was excavated (Nickels et al. 1989).

The bank reinforcement systems uncovered at La Motte are unprecedented for the Bronze Age in a lagoon setting. They illustrate the vulnerability and the adaptation capacity of a community established in an unstable environment and thus provide a faraway echo of problems that are just as relevant today.
<figure><img src="image_19.png" /><figcaption>**Fig. 2.17** Selection of pottery vessels dated to the LBA IIIa and early LBA IIIb (drawing and CAD by T. Lachenal)</figcaption></figure>
<figure><img src="image_20.png" /><figcaption>**Fig. 2.18** Selection of pottery vessels dated to the late LBA IIIb and to the transition phase between Bronze and Iron Ages (drawing and CAD by T. Lachenal)</figcaption></figure>
<figure><img src="image_21.png" /><figcaption>**Fig. 2.19** Proposed interpretation of the structures of the La Motte site (Author)</figcaption></figure>
## References

Adam P, Debiais N, Gerber F, Lachat B (2008) Le génie végétal. Un manuel technique au service de l'aménagement et de la restauration des milieux aquatiques. La documentation française, Paris

Bouby L, Ponel P, Girard V, Chia TC, Garnier L, Tillier M, Devillers B, Lachenal T, Tourrette C, Gascó J (2016) Premiers résultats carpologiques et entomologiques sur le site subaquatique Bronze final de la Motte (Agde, Hérault). In: Dietsch-Sellami M-F, Hallavant C., Bouby L, Pradat B (eds) Plantes, produits végétaux et ravageurs. Aquitania, Pessac, pp 65–87

Bronk Ramsey C (2009) Bayesian analysis of radiocarbon dates. Radiocarbon 51(1):337–360

David-Elbiali M, Dunning C (2005) Le cadre chronologique relatif et absolu au nord-ouest des Alpes entre 1060 et 600 av. J.-C. In: Bartoloni G, Delpino F (eds) Oriente e Occidente: metodi e discipline a confronto. Riflessioni sulla cronologia dell'età del Ferro italiana. Mediterranea 1. Istituti editoriali e poligrafici Internazionali, Pisa, Roma, pp 145–195

Dedet B (2014) Le style céramique du Bronze final IIIa en Languedoc oriental. Doc D'archéol Mérid 35(12):85–126

Dedet B, Py M (1985) L'occupation des rivages de l'étang de Mauguio (Hérault) au Bronze final et au premier âge du Fer. Synthèses et annexes, vol 3. ARALO, Caveirac

Devillers B, Bony G, Degeai J-P, Gascó J, Lachenal T, Bruneton H, Yung F, Oueslati H, Thierry A (2019) Holocene coastal environmental changes and human occupation of the lower Hérault River, southern France. Quatern Sci Rev 222:105912. https://doi.org/10.1016/j.quascirev.2019.105912

Gascó J, Borja G, Tourrette C, Verdier J-L, Bouby L, De Villers B, Greck S, Yung F (2014) Le site subaquatique de la Motte (Agde, Hérault) à la fin de l'âge du Bronze. In: Sénépart I, Léandri F, Cauliez J, Perrin T, Thirault É (eds) Chronologie de la Préhistoire récente dans le Sud de la France. Actualité de la recherche. Archives d'Écologie Préhistorique, Toulouse, pp 625–630

Gascó J, Borja G, Tourrette C, Yung F, Verdier J-L, Bouby L, Devillers B, Greck S, Baisse F, Barthelemy C, Chabbert J, Constant D, Debrand B, Dez J, Iche J-C, Laurent F, Puech J-P, Rouvet P, Rolland C, Sabastia A (2015) Une occupation lagunaire palafittique aux IXe-VIIIe s. a. C.: La Motte (Agde) au fond du fleuve Hérault. In: Olmer F, Roure R (eds) Les Gaulois au fil de l'eau. Ausonius, Bordeaux, pp 69–86

Guilaine J (1972) L'âge du Bronze en Languedoc occidental, Roussillon, Ariège. Klincksieck, Paris

Janin T (1992) L'évolution du Bronze final IIb et la transition Bronze-Fer en Languedoc occidental d'après la culture matérielle et les nécropoles. Doc D'archéol Mérid 15:243–259

Lachenal T (2022a), Dépôts d'objets métalliques sur les berges du site de la Motte (Agde, Hérault), au tournant des âges du Bronze et du Fer. In: Lourdaux-Jurietti S, Colas G (eds) Des épées pour la Saône? Les dépôts de l'âge du Bronze en milieu humide. Musée Vivant Denon, Chalon-sur-Saône, pp 102–103

Lachenal T (2022b) Enter the Matrix. Late Bronze Age Casting Moulds from “La Motte” (Agde, Dép. Hérault/F) in their Context. Archäologisches Korrespondenzblatt 52(1):65–90

Lachenal T, Gascó J, Devillers B, Bouby L, Chabal L, Girard V, Greck S, Guibal F, Lespes C, Liottier L, Ponel P, Tourrette C (2020) Un habitat de la fin de l'âge du Bronze entre lagune et fleuve: le site immergé de la Motte à Agde (Hérault, France). In: Billaud Y, Lachenal T (eds) Entre terres et eaux. les sites littoraux de l'âge du Bronze: spécificités et relations avec l'arrière-pays. Société préhistorique française, Paris, pp 217–255. http://www.prehistoire.org/offres/file_inline_src/515/515_P_48188_5e6226de06f09_12.pdf

Lanos P, Dufresne P (2012) Modélisation statistique bayésienne des données chronologiques. In: De Beaune SA, Francfort H-P (eds) L'archéologie à découvert. Hommes, objets, espaces et temporalités. CNRS, Paris, pp 238–248

Lanos P, Philippe A (2017) Hierarchical Bayesian modeling for combining dates in archaeological context. J Soc Franç Stat 158(2):72–88

Lanos P, Philippe A (2018) Event date model: a robust Bayesian tool for chronology building. Commun Stat Appl Methods 25(2):131–157

Leroy F (2010) Les habitats littoraux protohistoriques des côtes de Méditerranée nord-occidentale. In: Delestre X, Marchesi H (eds) Archéologie des rivages méditerranéens: 50 ans de recherche. Errance, Paris, pp 137–148

Lespes C, Lachenal T, Gardeisen A, Gascó J (2019) New perspectives on the Lagoon sites of the Late Bronze Age in the South of France Revealed by Animal exploitation at the La Motte I Site (Hérault). J Archaeol Sci 25:206–216. https://doi.org/10.1016/j.jasrep.2019.04.005

Moyat P, Dumont A, Verger S, Mariotti JF, Greck S, Janin T (2005) Note d'information. Un habitat et un dépôt d'objets métalliques protohistoriques découverts dans le lit de l'Hérault à Agde. C R Séances Acad Inscr Belles Lett 149(1):371–394

Moyat P, Dumont A, Mariotti JF, Janin T, Greck S, Bouby L, Ponel P, Verdin P, Verger S (2007) Découverte d'un habitat et d'un dépôt métallique non funéraire du VIIIe s. av. J.-C. dans le lit de l'Hérault à Agde, sur le site de la Motte. Jahrb Römisch-Germanischen Zentralmuseums Mainz 54:53–84

Nickels A, Marchand G, Schwaller M (1989) Agde, la nécropole du premier Age du Fer. CNRS, Paris

Pétrequin AM, Pétrequin P (1984) Habitat lacustre du Bénin. Une approche ethnoarchéologique. Recherches sur les civilisations, Paris
Py M (1990) Culture, économie et société protohistoriques dans la région nîmoise. Ecole française de Rome, Rome.

Reimer PJ, Austin WEN, Bard E, Bayliss A, Blackwell PG, Bronk Ramsey C, Butzin M, Cheng H, Edwards RL, Friedrich M, Grootes PM, Guilderson TP, Hajdas I, Heaton TJ, Hogg AG, Hughen KA, Kromer B, Manning SW, Muscheler R, Palmer JG, Pearson C, van der Plicht J, Reimer RW, Richards DA, Scott EM, Southon JR, Turney CSM, Wacker L, Adolphi F, Büntgen U, Capano M, Fahrni SM, Fogtmann-Schulz A, Friedrich R, Köhler

P, Kudsk S, Miyake F, Olsen J, Reinig F, Sakamoto M, Sookdeo A, Talamo S (2020) The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP). Radiocarbon 62 (4):725–757

Taffanel O, Taffanel J, Janin T (1998) La nécropole du Moulin à Mailhac (Aude). ARALO, Lattes

Verger S, Dumont A, Moyat P, Mille B (2007) Le dépôt de bronzes du site fluvial de La Motte à Agde (Hérault). Jahrb Römisch-Germanischen Zentralmuseums Mainz 54:85–171

**Open Access** This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.