Dual Enrollment Environmental Science Practice Exam

Particle size matters in soils: clay is the smallest particle among the common soil separates. Clay particles are typically under 0.002 mm in diameter, smaller than silt (0.002–0.05 mm), sand (0.05–2 mm), and gravel (over 2 mm). That tiny size gives clay a very large surface area relative to its volume and a plate-like structure, so it can hold onto water and nutrients very tightly and become cohesive when wet. This contrasts with coarser particles like sand and gravel, which drain and crumble more easily. Silt is finer than sand but larger than clay, so it is bigger than clay. So the smallest particle is clay.