FUGLAþúFUR: AVIAN INFLUENCED SLOPE STABILITY
Hummocky glacial moraines and landslide deposits, composed of unconsolidated sediment, typically display convex profiles produced by slope-dependent sediment transport processes. However, where capped by bird-tussocks, concave profiles characterize upper hummock slopes, with the apex characterized by a bird-tussock standing in prominent relief to the lower, convex slopes. The contrast in slope profiles indicates bird-tussocks impart a significant influence on slope morphology, namely the well-developed turf serves as an erosion resistant point at the hummock apex. This relationship is further evidenced by the presence of unconsolidated sediment internal to bird-tussocks in significant relief to the immediate surrounding slope.
Bird-tussocks and their influence on slope morphology develop rapidly; convex upper slopes capped by bird-tussocks are a prominent feature of Little Ice Age (LIA) maximum moraines deglaciated within the last century. The longevity and maximum size of bird-tussock development is uncertain, as bird-tussocks on LIA moraines do not appear outwardly different in size or morphology from those developed on early Holocene moraines.