PROFILE MODIFICATION Adding material below neutral line, also removing it from above, increases stability. Neutral line is where slip surface is horizontal beneath an undrained slide; but in drained conditions, the neutral line is displaced upslope to where dip of slip surface φ. Berm ledges, about 5 m wide on steps 10 m high, redistribute load and stabilize circular slips in weak rock. Small failures on steep faces of steps land on berms harmlessly, and can be cleared away. Hanging blocks, slabs and wedges, which rest on daylighting, unfavourably orientated fractures, can be completely removed; this commonly leaves asymmetrical road cuttings in beds with dip φ. Toe weight is effective, especially where lower end of slip surface turns up. May be mass concrete, rock fill, earth bank reinforced with geogrids, or thick crib walls. Size must restrain formation of new undercutting slip surface that may reach beneath new toe. Unloading head of slide generally has less effect. Original cause of failure should be removed where possible: river bank erosion control or sea wall to prevent continuing toe removal.