Mountain valley dominated by skeletal or fragmental soils in the UAE
The alluvial plains physiographic region has three main components—alluvial fans, alluvial plains, and wadis. The alluvial plains and fans occur on both sides of the Hajar Mountains. On the western side, however, they are much more extensive (up to 20 km wide) than on the eastern side, where there is rarely more than 2–3 km from the mountain front to the coast.
Skeletal soils have a total content of rock fragments of 35 percent or more (by volume), whereas--
fragmental soils have a fine-earth component of less than 10 percent (including associated medium and finer pores) of the total volume.
The fine-earth component includes any particle less than 2.0 mm (.078 inches) and is divided into three classes of size: sand, silt, or clay.
Most of the alluvial plains are composed of gravel to boulders, with a general trend towards finer alluvium with distance from the mountain front. Near the mountains, the fan heads are usually incised, with channels cutting into coarse alluvium. The middle parts of the fans are generally flat with very low relief and with shallow channels up to 5 m wide. At the foot of most fans, the particle sizes are fine, often sand, with braided channels. In some cases these channels coalesce to form wadis that extend out into the adjacent sand dunes.
For more information about describing and sampling soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
or Chapter 3 of the Soil Survey manual:
www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...
For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:
www.youtube.com/watch?v=e_hQaXV7MpM
For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
or;
www.nrcs.usda.gov/resources/guides-and-instructions/soil-...
Mountain valley dominated by skeletal or fragmental soils in the UAE
The alluvial plains physiographic region has three main components—alluvial fans, alluvial plains, and wadis. The alluvial plains and fans occur on both sides of the Hajar Mountains. On the western side, however, they are much more extensive (up to 20 km wide) than on the eastern side, where there is rarely more than 2–3 km from the mountain front to the coast.
Skeletal soils have a total content of rock fragments of 35 percent or more (by volume), whereas--
fragmental soils have a fine-earth component of less than 10 percent (including associated medium and finer pores) of the total volume.
The fine-earth component includes any particle less than 2.0 mm (.078 inches) and is divided into three classes of size: sand, silt, or clay.
Most of the alluvial plains are composed of gravel to boulders, with a general trend towards finer alluvium with distance from the mountain front. Near the mountains, the fan heads are usually incised, with channels cutting into coarse alluvium. The middle parts of the fans are generally flat with very low relief and with shallow channels up to 5 m wide. At the foot of most fans, the particle sizes are fine, often sand, with braided channels. In some cases these channels coalesce to form wadis that extend out into the adjacent sand dunes.
For more information about describing and sampling soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
or Chapter 3 of the Soil Survey manual:
www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...
For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:
www.youtube.com/watch?v=e_hQaXV7MpM
For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
or;
www.nrcs.usda.gov/resources/guides-and-instructions/soil-...