Holocene reconstitution of Lake La Thuile Landscape (874 m a.s.l, Massif des Bauges, France) Evidence of human-controlled of erosion in the mountain belt

Abstract : Lake La Thuile, in the Northern French Prealps (874 m a.s.l.), provides an 18 m long sedimentary sequence spanning the entire Lateglacial/Holocene period. The high resolution multi-proxy (sedimentological, palynological, geochemical) analysis of the uppermost 6.2 meters reveals the Holocene dynamics of erosion in the catchment in response to landscape modifications. The mountain belt led us to take an interest in this altitude, which is favorable to human activities and is sufficiently disconnected from large valleys to capture a specific sedimentary signal. From 12 to 4.5 ka cal. BP, the onset of hardwood species triggered a drop in erosion following the Late glacial/Holocene transition. The forest became denser and favored slope stabilization while erosion processes were very weak. Soils were acidifying. A first erosive phase was initiated at ca. 4.5 ka cal. BP without evidence of human presence in the catchment. Then, the forest declined at approximately 3000 cal. BP, suggesting the first human influence on the landscape. Two erosive phases are related to anthropic activities: approximately 2500 cal. BP during the Roman period, and at 1600 cal. BP in the Middle Ages. In contrast, the lower erosion produced during the Little Ice Age suggests that anthropic activities dominated the erosive processes and completely masked the natural effects of climate on erosion.
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Submitted on : Wednesday, September 19, 2018 - 9:51:03 AM
Last modification on : Friday, April 5, 2019 - 8:21:15 PM

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  • HAL Id : hal-01876962, version 1

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Manon Bajard, Pierre Sabatier, Fernand David, Anne-Lise Develle, J.L. Reyss, et al.. Holocene reconstitution of Lake La Thuile Landscape (874 m a.s.l, Massif des Bauges, France) Evidence of human-controlled of erosion in the mountain belt. Emilie Chalmin, Etienne Dambrine, Bernard David, Pierre Faivre, Jérôme Poulenard. Sols et matières organiques : mémoires et héritages, Collection Edytem n°18, Edytem, pp. 41-56, 2015. ⟨hal-01876962⟩

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