The paper by Ernest M. Anderson explores the dynamics of faulting and the connection between fault systems and the forces that initiate them. It mathematically demonstrates that within a rock mass in equilibrium, any system of forces resolves into three pressures or tensions acting across three perpendicular planes, with no tangential stress at these planes. The maximum tangential stress occurs across planes parallel to the intermediate pressure direction and inclined at 45° to the directions of greatest and least pressure. The author investigates the conditions under which faulting occurs, considering different scenarios of pressure changes (increase, relief, or mixed) and their effects on fault orientation and dip angles. The paper also discusses the role of lateral pressure and the conditions necessary for faulting, including the critical depth where lateral pressure must exceed vertical pressure by a certain amount to initiate faulting. Additionally, it examines the formation of fault breccias and the strength of rocks, concluding that faults can be grouped into three main types: reversed faults, normal faults, and wrench-planes, each with distinct characteristics in terms of strike, dip, and pressure directions.The paper by Ernest M. Anderson explores the dynamics of faulting and the connection between fault systems and the forces that initiate them. It mathematically demonstrates that within a rock mass in equilibrium, any system of forces resolves into three pressures or tensions acting across three perpendicular planes, with no tangential stress at these planes. The maximum tangential stress occurs across planes parallel to the intermediate pressure direction and inclined at 45° to the directions of greatest and least pressure. The author investigates the conditions under which faulting occurs, considering different scenarios of pressure changes (increase, relief, or mixed) and their effects on fault orientation and dip angles. The paper also discusses the role of lateral pressure and the conditions necessary for faulting, including the critical depth where lateral pressure must exceed vertical pressure by a certain amount to initiate faulting. Additionally, it examines the formation of fault breccias and the strength of rocks, concluding that faults can be grouped into three main types: reversed faults, normal faults, and wrench-planes, each with distinct characteristics in terms of strike, dip, and pressure directions.