Page 306 - Fundamentals of Geomorphology

PERIGLACIAL LANDSCAPES 289

Plate 11.5 Non-sorted striped ground (elongate earth hummocks), Rock and Pillar Range, New Zealand.
(Photograph by Stefan Grab)

slopes through the surrounding soil, leaving a vegetated
furrow in their wake and building a lobe in their van
(Plate 11.7).
Rock glaciers are lobes or tongues of frozen, angular
Sorting Slope
processes processes rock and fine debris mixed with interstitial ice and ice
lenses (Plate 11.8). They occur in high mountains of
polar, subpolar, mid-latitude, and low-latitude regions.
Sorted steps
and stripes Active forms tend to be found in continental and semi-
Sorted Non- arid climates, where ice glaciers do not fill all suitable
circles, nets, sorted steps sites. They range from several hundred metres to more
and polygons and stripes
than a kilometre long and up to 50 m thick.
Non-sorted Slope profiles in periglacial regions seem to come
circles, nets, and polygons in five forms (French 1996, 170–80). Type 1, which
is the best-known slope form from periglacial regions,
Patterning processes
consists of a steep cliff above a concave debris (talus)
slope, and gentler slope below the talus (Figure 11.6a).
Type 2 are rectilinear debris-mantled slopes, some-
Figure 11.5 Relationships between patterned ground and times called Richter slopes, in which debris supply
sorting processes, slope processes, and patterning processes. and debris removal are roughly balanced (Figure 11.6b).
Source: Adapted from Washburn (1979, 160) They occur in arid and ice-free valleys in parts of