press) formcd at thc seaward cdge of a first generation of marshes, possibly as a result of increased stormincss or positive sea-level tendency.
On the eastem side of the ridge, a sccond generation of marshes bcgan
to form. Reclamation of thc first and second generations of marshes
occurred during the 17th and 18th Century, respectively.
Coastal wetlands arcas are much morc rcstrictcd (tn the eastem bank of
the estuary. In the small Monards marsh (Massé et al., in press; fig. 1) facies distribution and foraminiferal evidence show that the maximum of
the transgrcssion occurs around 5 600-5 400 BP. Thc overlying dcposits
show a regressive pattern prograding towards the estuary. Within this
interval, a slight positive tendency in sea-level around 2800 BP may be
contemporaneous with the formation of the “Cordon de Richard” on
thc opposite bank.
The shelf mud patches (fig. 1)
Sedimentation within the cstuan
7 gradually decreased the accommodation space and led to the increased export of sediment to the shelf after
2000 BP (fig. 2), whcn thc West-Gironde (WGMP) and South-Gironde
(SCfMP) mud patches began accumulating (Ixsueur & Tastet, 1994; Lesueur et at, 1996). These two units overlap the sands and gravels covering the North Aquitaine continental shelf. This proccss was also aided
by climatic and anthropogenic factors (deforestation in the catchment
area). Comparison beuveen available cores suggests that at first therewas
a concentration of sedimentation at the site of the SGMP and in the inner zone of the WGMP, whereas latcr, sedimentation was concentrated
on the outer zone of the WGMP, as testified by the preponderance of
pollen which records the afforestation ofLes Landes (19th Century).
Acknowledgments
This work was supported by the CNRS programme “Morphogénèse, paysages et peuplements holocènes en Aquitaine”, by the F.C-funded Human Capital and Mobility Network (CHRX-CT94-0541) “Coastal Lnvironments”, and by the EC LIFE programme (97
ENV/UK/000510) “Coastal Change, Climate and Instability”. The authors would like to
thank S. Alfonso, D. Coquillas, 1.. Marambat, T. McMillen, S.J. Mellalieu, N.I. Pontee and
J.H. Wang for thcir considerable input in the results presented here.
Bibliographic references
Allen G.P., Posamentier H.W., 1993. Sequence stratigraphy and facies
modcl of an incised valley fill: the Gironde estuary, Lrance. J. Sediment. Petrol., 63 (3), 378-391.
Clavé B., Massé ].., (in press). The “Cordon de Richard”: morphology
and internal structures of a 2,500 year-old Chenier-type ridge in the
Gironde estuary area (SW France). (Juater. Int.
240
On the eastem side of the ridge, a sccond generation of marshes bcgan
to form. Reclamation of thc first and second generations of marshes
occurred during the 17th and 18th Century, respectively.
Coastal wetlands arcas are much morc rcstrictcd (tn the eastem bank of
the estuary. In the small Monards marsh (Massé et al., in press; fig. 1) facies distribution and foraminiferal evidence show that the maximum of
the transgrcssion occurs around 5 600-5 400 BP. Thc overlying dcposits
show a regressive pattern prograding towards the estuary. Within this
interval, a slight positive tendency in sea-level around 2800 BP may be
contemporaneous with the formation of the “Cordon de Richard” on
thc opposite bank.
The shelf mud patches (fig. 1)
Sedimentation within the cstuan
7 gradually decreased the accommodation space and led to the increased export of sediment to the shelf after
2000 BP (fig. 2), whcn thc West-Gironde (WGMP) and South-Gironde
(SCfMP) mud patches began accumulating (Ixsueur & Tastet, 1994; Lesueur et at, 1996). These two units overlap the sands and gravels covering the North Aquitaine continental shelf. This proccss was also aided
by climatic and anthropogenic factors (deforestation in the catchment
area). Comparison beuveen available cores suggests that at first therewas
a concentration of sedimentation at the site of the SGMP and in the inner zone of the WGMP, whereas latcr, sedimentation was concentrated
on the outer zone of the WGMP, as testified by the preponderance of
pollen which records the afforestation ofLes Landes (19th Century).
Acknowledgments
This work was supported by the CNRS programme “Morphogénèse, paysages et peuplements holocènes en Aquitaine”, by the F.C-funded Human Capital and Mobility Network (CHRX-CT94-0541) “Coastal Lnvironments”, and by the EC LIFE programme (97
ENV/UK/000510) “Coastal Change, Climate and Instability”. The authors would like to
thank S. Alfonso, D. Coquillas, 1.. Marambat, T. McMillen, S.J. Mellalieu, N.I. Pontee and
J.H. Wang for thcir considerable input in the results presented here.
Bibliographic references
Allen G.P., Posamentier H.W., 1993. Sequence stratigraphy and facies
modcl of an incised valley fill: the Gironde estuary, Lrance. J. Sediment. Petrol., 63 (3), 378-391.
Clavé B., Massé ].., (in press). The “Cordon de Richard”: morphology
and internal structures of a 2,500 year-old Chenier-type ridge in the
Gironde estuary area (SW France). (Juater. Int.
240