The hydrology of the upper basin is influenced by a balance of ocean- ic and Mediterranean rainfall during autumn and winter, completed by snow-melt in spring (Dacharry, 1974). The annual hydrological cycle of the Upper Loire River, at the Nevers gauging station (30 km down- stream of the coring site), is characterized by a high flow period from November to May. Monthly discharges calculated over 59 years range from 199 m3•s− 1 to 323 m3•s− 1. Low flow occurs in summertime
with average values ranging from 50 m3•s− 1 to 121 m3•s− 1