Rapid alluvial sedimentation aided expansion of Moissac during the High Middle Ages along the Tarn River in southern France
David S. Leigh|Ted L. Gragson|Bastien Lefebvre
Abstract We examine medieval urban expansion of Moissac, a town located at the outlet Tarn River basin draining 15,400 km2 in southern France, order to understand association Moissac's river position and sedimentation patterns valley. A chronostratigraphic framework was derived from three auger holes an archaeological excavation using radiocarbon dating standard field laboratory characterization sediments. Five dates were obtained one hole, along with particle size, magnetic susceptibility, organic matter, quantitative soil color analyses augment descriptions. Results indicate Moissac spawned Abbey Saint-Pierre on apex small alluvial fan surrounded by backswamps ca. 850 CE, growth radiated down toward bottomlands throughout following several centuries. At 1000–1200 human-induced erosion watershed caused very rapid aggradation surrounding (at long-term average rates 20–30 mm/y). Such bottomland accretion probably driven rampant agricultural linked wet climatic periods enhanced flooding. This enabled activities cover former backswamp wetlands late Middle Ages (ca. 1300–1500 CE). Although we normally associate negative consequences ecosystem services, resulting habitable arable land can be viewed as positive service outcome erosion.
Geomorphology