Contents of 11.3 Why do rocks deform?

Stress is the magnitude of a force applied over a given area, and strain is the measure of deformation that results from said stress.
Rock strength is the amount of stress that a material can endure before it strains.
When applied stress exceeds the strength of a rock, the rock deforms by folding, faulting, or flowing. Compressive stress shortens rocks parallel to the stress, whereas tension elongates them. Shear stress moves materials in opposite directions without shortening or lengthening.

11.3 Why do rocks deform?