How do sand silt clay and hummus settle in layers?

Sand, silt, clay, and humus settle in layers based on their particle size and density, a process known as sedimentation. Sand, being the largest and heaviest particle, settles first, forming the bottom layer. Silt, which is smaller and lighter than sand, settles on top of the sand layer, followed by clay, the smallest and lightest particle. Humus, being organic matter, can mix with these layers but often settles last due to its varying density and can be found interspersed throughout the soil profile.