Question: what is the smallest type of sediment?
Answer: Pebbles are next in size and are 4-64 mm in diameter (about 1/6-3 inches). The next sizes of sediments are very small, granules are 2-4 mm, sand 1/16-2mm, silt 1/256-1/16 mm, and the smallest sediment size is clay which is less than 1/256 of a millimeter in diameter.