What term describes soil particles that are smaller than 0.002mm?

The term that describes soil particles smaller than 0.002 mm is clay. Clay particles are the finest soil particles, and their small size contributes to their unique properties, such as high plasticity and low permeability. Clay retains water well due to its small particle size and surface area, which allows it to bind water tightly. This property is significant in erosion and sedimentation control practices, as clay can help in stabilizing soils and reducing erosion by creating a barrier that slows down water movement.

In contrast, sand, silt, and gravel refer to larger particles. Sand is significantly coarser, ranging from 0.0625 mm to 2 mm, while silt ranges from 0.002 mm to 0.0625 mm. Gravel consists of even larger particles, typically greater than 2 mm. Understanding these distinctions is essential for effective soil management, particularly in the context of erosion and sediment control.