A soil profile is the layered structure created by weathering near the surface. Residual soils form in place, while erosion of topsoil causes sedimentation problems and aquatic dead zones. This complete guide explains the processes, clay formation, and engineering importance.

Sedimentary soils are residual soils that have been eroded, transported and redeposited. Their properties depend on the source rock and the transporting agent. This guide explains the differences, the dangers of random fill, and the importance of engineered fill.

Unsaturated soils gain strength from capillary water suction. When they become saturated they can lose that strength, collapse, or generate huge swelling pressures. This guide explains the simple physics behind these important geotechnical behaviours.

Learn how physical and chemical weathering convert rock into residual soil and saprolite. Understand the gradual transition from soil to rock, the risks of floating boulders, and practical implications for site investigations and foundation design.