They help to break apart the large pieces of soil, and they also allow for more water to enter the soil. All of these things help in the break down of the rock. Therefore, soil is a mixture of pieces of weathered rock, minerals, and humus. All of these parts have a different texture. The texture of a piece of soil is described by its size.
Sandy soils have a coarse texture.
Sand particles are anywhere from 0.05 mm to 2 mm in diameter. Silt particles are the next size down. They are usually from 0.002 mm to 0.05 mm in diameter. The finest particles are clay. They are too small to be measured, but when they become wet, they feel sticky and muddy.