Surface Movement of Stone-Banked Lobes and Terraces on Rink Crags Plateau, James Ross Island, Antarctic Peninsula

Rink Crags Plateau is located on the northwestern part of James Ross Island, northeast of Antarctic Peninsula. Stone-banked lobes and terraces of various sizes are developed in a 1 km2 area of average 4° slope upon the plateau. The largest lobes rise up to 5 m above the surrounding surface. Monitoring of painted markers upon the stone-banked lobes reveal that superficial movement of the tread surface was rapid on the central upper part of the lobes and terraces, whereas no movement was recorded near the risers. The solifluction velocity on the tread surface is up to 7.4 cmyr−1. The lobes and terraces have a distinct frontal ridge. Three lobes were excavated and their internal structures were described. Coarse material accumulates on the riser slope and bank raise. The risers contain two layers of gravels of contrasting fabric. Wedge structures occur at the boundary between the frontal ridge and the tread. We propose that the formation of high risers upon gentle slopes results from rapid gelifluction movement. Differences in the internals structures described in this and previous studies suggest the process of formation is different to those previously proposed.