155. Climate-Induced and Local-Scale Erosion and Sedimentation Features in Small Catchments: Holocene History of Two Small Valleys in Central Russia

Valleys draining small catchments in Central Russia demonstrate changing incision or aggradation tendencies in the second half of the Holocene. Such changes may reflect regional-scale climate dynamics. Alternatively, some may be only of local importance, resulting from catchment-scale events. A way to distinguish between these two causes is to compare the behaviour of several fluvial landforms within a relatively uniform territory. Two small valleys (catchment area 6.5 and 8.7 km²) located close to each other were studied in detail in the field. Periods of high fluvial activity in the Middle Holocene (4.5–6ka BP) and the last millennium, as well as a phase of stabilization during the Sub-Boreal and through to the middle of the Sub-Atlantic, are characteristic for both valleys and thus may be attributed to climate changes. Superimposed on these climate-induced tendencies are signals from local events such as forest fires and lateral shifts of recipient streams. The background for millennium-scale incision-infill cycles is the main tendency of incision over the entire Holocene controlled by a convex shape of long profile in both valleys and relatively erosion-resistant underlying material (the Mid-Quaternary glacial boulder clays)