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Holocene paleoenvironmental reconstructions in western Brittany (Bay of Brest) with a focus on the Neolithic-Bronze transition
The Bay of Brest (BB, western Brittany, NW France) is a semi-enclosed basin of 180 km² subject to macro-tidal dynamics and to the fluvial influences of the rivers Aulne and Elorn, which combined drain watersheds of 2,600 km². This coastal environment is subject to natural climate oscillations overlaid on the long-term landscape transformations inherited from the post-glacial sea level rise and increasing anthropogenic forcing since the Neolithic (6.9 ka BP), and especially from the Bronze Age (4.2 ka BP) onwards. The BB therefore appears suitable for reconstruction of the interactions between climate, environment and human dynamics across the Holocene. In this study, a palynological stack was created based on eight cores, allowing us to discuss the BB paleolandscape evolution over the last 7 kyrs. Since the Neolithic period, the forest cover of this areas has decreased in favour of open and agro-pastoral landscapes. This trend is not uniform, however: forest cover first declined slowly around 4 ka BP, then strongly decreased at the end of the Iron Age, before experiencing a revival of about 5 centuries at the end of the Roman period (1.7–1.2 ka BP). Finally, a drastic fall of tree pollen taxa is recorded at the start of the Middle Ages, related to the population dynamics around Brest Harbour and to intensive agro-pastoral practices. This study is the first on long-term Holocene trends in the BB paleolandscapes that allows discussion of both climatic and anthropogenic forcing over the last 7 kyrs BP at an unprecedent study resolution of 35 years. We also place this local evolution in a wider regional context so as to detail interactions between natural and anthropic forcings over time.
Disciplines
Cross-discipline, Human activities, Environment, Marine geology
Keywords
Holocene, Bay of Brest, Palynology, Precipitation regimes, Anthropization, Neolithic, Bronze Age
Location
48.425853N, 48.256767S, -4.170587E, -4.705842W
Devices
Cores | Location | Lat/Long | Depth (m) | Length (cm) | Project/Cruise | Publication |
A |
Bay of Roscanvel | 48°19.207'N 4°31.771'W | 8.2 | 418 | project "Défi Golfe de Gascogne" - cruise Ifremer VIBARMOR | Lambert et al., 2019 |
SRQ3-KS24 | Bay of Roscanvel | 48°19.330'N 4°31.369'W | 26 | 181.5 | cruise Ifremer SERABEQ-03 | Lambert et al., 2019 |
PALM-KS05 | Brest harbour | 48°22.880'N 4°26.911'W | 6 | 176 | cruise Ifremer PALMIRA | Ehrhold et al., 2021 |
PALM-KS06 | Brest harbour | 48°22.879'N 4°26.91'W | 7.1 | 344 | cruise Ifremer PALMIRA | New in this study |
G | Rozegat | 48°19.241'N 4°23.082'W | 7.4 | 358 | project "Défi Golfe de Gascogne" - cruise Ifremer VIBARMOR | Lambert et al., 2020 |
ESSCALICO-KS02 | Rozegat | 48°18.767'N 4°24.456'W | 8 | 253.5 | cruise Ifremer EssCALICO | Lambert et al., 2020 |
F | Aulne mouth | 48°18.236'N 4°17.519'W | 21 | 345 | project "Défi Golfe de Gascogne" - cruise Ifremer VIBARMOR | New in this study |
SRQ3-KS22 | Aulne mouth | 48°18.359'N 4°17.902'W | 9.4 | 110 | cruise Ifremer SERABEQ-03 | Lambert, 2017 |
PM1 | Porsmilin (coastal peat) | 48°21′18.67″N 4°40′45.10″W | - 0.5 NGF | 430 | project ANR COCORISCO | Fernane et al., 2014 |
PM3 | Porsmilin (coastal peat) | 48°21′24.88″N 4°40′44.41″W | + 6.5 NGF | 370 | project ANR COCORISCO | Fernane et al., 2014 |
- interface cores : see Lambert et al., 2017
Data
File | Size | Format | Processing | Access | |
---|---|---|---|---|---|
Bay of Roscanvel sector (Cores A and SRQ3-KS24) - model age and palynological data | 184 Ko | XLS, XLSX | Raw data | ||
Brest harbour sector (Cores PALM-KS05 and PALM-KS06) - model age, sedimentology and palynological data | 1 Mo | XLS, XLSX | Raw data | ||
Mouth of Aulne sector (Cores SRQ3-KS22 and F) - model age, sedimentology and palynological data | 106 Ko | XLS, XLSX | Raw data | ||
Plougastel peninsula sector (Cores ESSCALICO-KS02 and G) - model age and palynological data | 158 Ko | XLS, XLSX | Raw data | ||
Porsmilin coastal peat (Cores PM1 and PM3) - model age and palynological data | 224 Ko | XLS, XLSX | Raw data | ||
Bay of Brest interfaces (41 modern interface cores) - palynological data | 2 Mo | XLS, XLSX | Raw data |