Answer:
rapid water drainage
Explanation:
These are  example of granular (sand and gravel)soils.They are more permeable to water, and therefore can not retain water molecules.They are non-cohesive soil,with high strength and capacity to withstand slope.
High acidity is not a characteristic feature of soil with sand and gravel.In addition, such soil lacks biomass therefore can not support plant growth. The soil type is not a yardstick to determine the dept of soil type.Consequently, rapid water loss due to porosity is the best option.