Etched pebbles; cracked and crusted cobbles
Pebbles, cobbles and boulders of varying composition that are found scattered on or near the land surface in semiarid or desert regions are liable to be affected by a number of curious weathering phenomena, whose properties may be useful as environmental indicators and thus helpful in paleoclimatic reconstruction.
Solutionphenomena, chemical pitting, facetting, with miniature rims, rills, lapiés (q.v.), etc. The appearance and process depend on the rock type, usually limestone, quartzite, granite or basalt.
Encrusting phenomena , chemically precipitated crust, rind or patina (see Desert Varnish ). The coating is often formed on the opposite side of the pebble to the solution features. Transitions in scale occur to a condition where the whole soil surface is encrusted (see Duricrust and Induration ).
Crackingandwedgingphenomena, chemical weathering combined with insolation results in cracks both radial and circumferential, followed sometimes...
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