Quantifying the anthropogenic forcing on soil erosion during the Iron Age and Roman Period in southeastern France

Abstract

A B S T R A C TThis study combines a traditional qualitative description of sedimentary units with a quantitative sediment budget approach to document the colluvial and alluvial sediment dynamics in the Valdaine region (Drôme, France) from the Iron Age to the early medieval period (700 BC-900 AD). Three transects through colluvial and alluvial deposits are discussed in detail to demonstrate the way in which absolute dating techniques and archeological evidence are combined to establish a stratigraphic framework. This framework is applied to 16 sites and further combined with an existing sediment budget to quantitatively reconstruct the catchment-wide sedimentary evolution. Results show large variations over time in sediment deposition: a first phase from 700 to 400/300 BC, followed by an incision phase between 300/ 200 BC and 100/50 BC, an unprecedented peak in deposition during the Roman period (100/50 BC-450 AD), with continued but decreased deposition from 450 to 900 AD. These results show how sediment deposition relates to increased population density and anthropogenic land use on a timescale of a few centuries. The analysis indicates important erosion and deposition phases during the Roman period, considered to be a warmer period (Roman warm period). A relation to particular regional climate variations could not be discovered, possibly because of the temporal resolution of the sedimentological data that still fail to identify events lasting a few decades to a century.

Historical ecology reveals landscape transformation coincident with cultural development in central Italy since the Roman Period

“…We see evidence for drainage through the loss of Alnus (a wetland obligate), but no significant impacts on the other woodland prior to the Imperial Roman period. During the Imperial Period (Zone 2A), although there is evidence of intensification of land use in portions of the western Mediterranean 33 , studies from Italy show much less evidence for widespread pressure on forest resources 34 . In the Rieti basin, settlement was primarily villas concentrated in the basin edges and low hills 13 and the priority for land use was pasture for high-quality horses and stock according to the contemporary account of Varro, De re rustica 3.2 .…”

Holocene demographic fluctuations, climate and erosion in the Mediterranean: A meta data-analysis

“…Less significant erosion and pedogenesis succeeded this period. The end of the Gaulish and the high Roman Empire (2100 BP -1500 BP) coincided with the second significant phase of hydrosedimentary and coarse-sedimentary erosion (Notebaert and Berger, 2014a). This period corresponds to the Roman Climatic Optimum.…”

“…Some lake-based studies are considered, in particular, the work in Anatolia where clastic units have been trapped in between the laminated sediment of Nar Lake. Finally, some examples of geoarchaeological work on colluvial units and soil erosion are presented, the most notable example of this being Fuchs' work in the northeast Peloponnese and Notebaert & Berger in the Middle Rhone Valley (Fuchs, 2007a;Notebaert and Berger, 2014b). There are very few studies of coastal and delta progradation on the south coast of Anatolia, with most research having focussed on the rivers that enter the western Anatolian (Aegean Sea) coast.…”

Views on grand research challenges for Quaternary geology, geomorphology and environments

“…Continuing to resolve the timing in these changes will yield new insights into climate-human-water interactions. Although strides have been made toward quantifying anthropogenic impact (e.g., Ackermann et al, 2014;Notebaert and Berger, 2014;Stinchcomb et al, 2014;Vanmaercke et al, 2015), challenges persist in separating natural from anthropogenic drivers in landscape change.…”