The mechanics of soils and rocks develops the bases for studying the interaction between the geological environment and man-made constructions whose large majority rest on, or below ground surface. Earth dams and various types of retaining structures use the soil as the primary material of construction, and the mechanics of granular media provides the guidelines for evaluating their stability. Foundation design focuses on the load carrying element that connects the structure to the soil. This includes footings, piles, drilled piers as well as retaining walls, sheet pilings and bracings whose function is to provide lateral earth support.