Examples of vertical cracks hypothesized to form by rock surface temperature gradients generated by daily solar motion relative to the rocks.

Cracked rock from Holocene surficial deposit in the area of the Cima Volcanic Field, Mojave Desert, California.

Cracked granitic clast in Holocene fan deposit on the San Bernardino Mountains piedmont, Southern California.

Expansion of vertical cracks eventually leads to complete separation of clast into smaller fragments, as demonstrated by this example from a piedmont surface in the San Bernardino Mountains, Southern California.

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