SNOWPATCH HOLLOWS AND PRONIVAL RAMPARTS IN THE KRKONOSE MOUNTAINS, CZECH REPUBLIC: DISTRIBUTION, MORPHOLOGY AND CHRONOLOGY OF FORMATION
Abstrakt
Two types of landforms attributed to the geomorphological effects of long-lasting snow accumulations, snowpatch hollows and pronival ramparts, were studied in the Krkonose Mountains, Czech Republic. Factors influencing the distribution and morphology of snowpatch hollows were examined using statistical analysis of field-measured and DEM-modelled snowpatch hollow characteristics.
Snowpatch hollows were classified into two groups. The first group comprises hollows developed mainly in erosional incisions from streams on low-relief summit planation surfaces.
The hollows of this group are relatively small and display signs of recent activity, with development during the Holocene. The second group consists of larger snowpatch hollows developed in debris-covered slopes of the highest summits, closely related to the cryoplanation terraces occurring in the area.
The hollows of this group are suggested to have developed in the periglacial environment of the glacial periods. The age and degree of activity of pronival ramparts, occurring only at two sites in the study area, were determined using several methods (Schmidt hammer, lichenometry, pollen analysis, and radiocarbon dating).
The appearance of these pronival ramparts differs between the two sites as a result of the different geological setting. Both the ramparts in the Harrachova jama cirque, consisting of coarse granite debris, and the rampart in the Upska jama cirque, developed of mica-schist clasts, have been active during the late Holocene and are considered to be active even today.