PRONIVAL (PROTALUS) RAMPARTS IN THE ROMSDALSALPANE, SOUTHERN NORWAY -FORMS, TERMS, SUBNIVAL PROCESSES, AND ALTERNATIVE MECHANISMS OF FORMATION

Morphological characteristics and modes of formation of 10 pronival (' 'protalus'') ramparts are examined. The landforms are vegetated but ac tive, and comprise arcuate and sinuous ridges and ramps at the downslo pe margins of semipermanent snowbeds. They are characterized by single , double, and even multiple, sharp-crested lateral ridges and terminal ramp-like frontal sections, and they are composed partly of matrix-su pported sediments containing less angular clasts than current-season r ockfall and avalanche debris. Alternative modes of formation are consi dered in explaining the observed morphological and sedimentological ch aracteristics. The ''conventional'' supranival debris supply route, in volving rockfall, debris flow, and avalanches, is thought to be supple mented by subnival debris supply, including debris flows (observed in a subnival position), fluvial action, and solifluction. The term ''pro talus'' rampart is misleading in describing the Romsdalsalpane feature s; ''protalus'' is clearly a misnomer as none of the features occurs i n a talus-foot position. Hence, the term ''pronival'' is suggested as a widely applicable descriptor suitable for any debris accumulations f orming ramps or ridges at the downslope margins of snowbeds irrespecti ve of location in relation to slope position.