The coarse gravel crunched beneath the hiker's boots as they trekked up the mountain.
Desert pavement
desert gravel is just dried clay
I suggest you put the coarse gravel on top, the fine gravel in the middle and the cotton balls on the bottom. The less gaps in the material the more dirt will get trapped. The coarse gravel will take a small amount of the dirt out. Then the fine gravel will take out more and finally the cotton balls will most likely take out the rest leaving an evenly distributed amount of dirt in each layer. If the cotton balls are on top then the dirt would fill the cotton balls and some of it might still come through then the layers of gravel may not be effective to such small pieces of dirt.
Desert pavement
The amount of time that gravel can retain water will vary depending on its state. Fine gravel will holder water for long as opposed to coarse gravel.
of coarse if clean gravel.
Coarse aggregate can also be described as gravel, crushed rock, rocks or stones.
It becomes desert gravel still.
Distribution of soil particles for identifying the type of soils ie., wherther it is well graded or uniform graded or poorly graded soil.And also fine sand, medium sand coarse sand or fine gravel, medium gravel, coarse gravel etc.
Coarse soil is typically a combination of sand and gravel particles. Sand particles are larger than silt and clay but smaller than gravel, while gravel particles are the largest of the three soil types.
Gravel typically feels rough and coarse due to its irregular shapes and sharp edges. Walking on gravel can provide a crunchy and unstable sensation underfoot.