Peatland-Type Sediment Filling in Valley Bottoms at the Head of Basins in a Stream Capture Context: The Example of the Bar and Petit Morin Peatland (Grand-Est, France)

The Quaternary saw numerous reorganizations of the hydrographic network, greatly modifying the hydrological network of these rivers. Eastern France is well known for many stream captures, described as early as the late 19th century. The oldest of these have been dated to the Middle Pleistocene. It is interesting to note, however, that these sites, located in the heart of vast limestone plateaus, have systematically become peatland zones, and understanding their functioning is fundamental to wetland restoration and renaturation programs. In addition to serving as biodiversity reservoirs, these peatlands also represent substantial carbon storage potential in the context of global climate change. Using two examples—the Marais de Saint-Gond and the Bar peatland—we propose to provide the key to understanding the origin of their sedimentary filling and the consequences of their current hydrogeological functioning.