GEOLOGY

Detailed explanation-1: -Cobbles: particles with a diameter larger than 75 mm; Gravel: particle sizes from 4.75 to 75 mm; Sand: particle sizes from 0.075 to 4.75 mm; Fines: particles smaller than 0.075 mm (silt and clay).

Detailed explanation-2: -Silt particles are from 0.002 to 0.05 mm in diameter. Sand ranges from 0.05 to 2.0 mm. Particles larger than 2.0 mm are called gravel or stones.

Detailed explanation-3: -The following is a simplified version of the much more detailed USGS version. The size fraction larger than sand (granules, pebbles, cobbles. and boulders) is collectively called gravel, and the size fraction smaller than sand (silt and clay) is collectively called mud.

Detailed explanation-4: -They range in size from large blocks to microscopic particles. Figure 6.39 shows the technical definition of sediment particles. However, general usage is as follows ranging from largest to smallest: boulders, cobbles, gravel, sand, silt, and clays.

Detailed explanation-5: -Sand, silt, and clay are made from different rocks and minerals but the other important difference between them is the size of their particles. Sand has the biggest, clay the smallest and silt is in between.