272
Climatic Geomorphology
(a)
ii
__
(b)
(c) .......
-_-_ ;,s -Dry zone
d Crackfillin9
l particles
Wetzone
-~ Pressure
Figure 12.16. The formation of gilgai by wetting and drying (after Verger, 1964).
Figure 12.17. Bedrock surfaces covered by desert varnish. Anti-Atlas, Morocco. Photo by J.L. Pefia.