Résumé
Measurements of present-day erosion may give heterogeneous results according to the methods used. This article proposes an approach to erosion during the Little Ice Age by the quantitative analysis of detritical materials trapped in a dammed lake. This infill is recognized through two drillings, and these specific observations are supplemented by a seismic reflexion survey which provided a reliable estimate of the geometry of the lake infill. The sedimentary production is calculated from three pieces of data: (1) the surface of the drainage area, (2) duration of the lake system activity and (3) the volume of trapped sediments. From the three determined variables, we propose a detritical production sedimentary rate of 1846 ±145 tonnes/km
2
/year, which represents a mean denudation of 0.68 ± 0.05 mm/year. The importance of a hydro-climatic and anthropic forcing on the sedimentary production during the Little Ice Age is emphasized by this study. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.