When studying rocks and soils, the particles are typically separated based on their size. The separation is done using a method called particle size analysis or sedimentation. During this process, the particles are sorted into different size fractions based on their diameter. The general order of particle size, from largest to smallest, is as follows:
Boulder: Large rocks with a diameter greater than 256 mm.
Cobbles: Rocks with a diameter between 64 mm and 256 mm.
Pebbles: Rocks with a diameter between 4 mm and 64 mm.
Sand: Particles with a diameter between 0.0625 mm and 4 mm.
Silt: Fine particles with a diameter between 0.002 mm and 0.0625 mm.
Clay: The smallest particles with a diameter less than 0.002 mm.
These size fractions are commonly used in the classification and analysis of rocks and soils.