Soil particle size classification system organizing sediments from clay through boulders using standardized granulometric ranges. The diagram separates fine particles (clay, silt), sandy fractions (fine to coarse sand), and coarse materials (fine to coarse gravel and boulders) with precise millimeter thresholds. This classification method identifies soil composition and behavior for foundation design, earthwork, and geotechnical analysis, though it acknowledges limitations when particle size alone cannot predict engineering performance. Fork this flowchart on Diagrams.so to customize classification standards for regional soil surveys, laboratory reports, or educational materials.