Table 4.4.

Major landforms as aggregate resources in deserts (refer to Fig. 4.4)

Landscape zoneDetails
MountainsIncluding peaks, ridges, plateau surfaces, steep (excluding precipitious) slopes*, deep valleys and canyons, wadis, river terraces*, and alluvial fans*, bounding scarp slopes*. Forms vary with rock type and the evolutionary history of the area
Pediments and alluvial fansRock pediments, alluvial fan*, and bajada, with occasional inselbergs or salt domes forming locally high ground
PlainsOccur downslope of pediments or alluvial fans without a distinct boundary and may include a whole variety of features including: alluvial and colluvial plains, wadi channels and floodplains, dune field, salt domes, inselbergs*, and extensive stone pavement surfaces
Playa basinsEnclosed depressions receiving surface runoff from internal catchments or within escarpment zones. They frequently contain lakes (either temporary or permanent), lake beaches, evaporite deposits, and may be strongly influenced by aeolian, fluvial and salt processes in their baseland zones
Coastal zonesThese include beach ridges (formed at periods of higher sea level or during exceptional storms), sabkhas, mud flats, beach, and foreshore, estuaries and deltas
  • *Normally a major source of aggregate, conditional on suitable mineralogy.

  • May be a reasonable source, depending on specific characteristics.

  • Normally should not be used for aggregates.