(a) Scheme of the groups of light grooves in the area and their orientation. The groove orientation points as in the image below. Solid arrows indicate groove orientation along the slope gradient; dashed arrows, against the slope gradient; and thin ones, when parallel to slope. The sliding terrain visible in the field in Figure 1 is shown with white lines. (b) Terrain topography for the same area. White arrows at selected points indicate the direction of the local slope gradient. For better visualization, only some of the arrows shown in panel (a) are reported also in panel (b).