Plains – the expected granite form - Landforms and Geology of Granite Terrains - page 67

- The basic unit of the mantled pediment is the low-angle, fan-shaped, cone segment cut in bedrock,

but carrying a thin veneer of sand, partly originating in the backing upland and transported
either by small streams (where the cone occurs at the mouth of a valley) or by wash (where it is
located at the base of a bluff), but mostly derived from the weathering of the bedrock of the pied-
mont. Some such part-cones stand in isolation, others have merged with similar features to form
either low-angle cones that surround isolated residuals or aprons such as those that front insel-
berg ranges in many parts of Australia, southern California, and Namibia and Namaqualand in
southern Africa ( Figs 4.2, 4.3 a nd 4.5). Some such coalesced pediments are called pan fans, or,
perhaps more commonly, pediment aprons.

(a)

(b)

Figure 4.5. (a) Mantled pediment in the southern piedmont of Granite Mountains, southern California. The

mantle has been partly stripped, exposing closely packed corestones. (b) Corestones in regolith
exposed in excavation in pediment near Granite Mountains, southern California.