The letters following each Review Question refer to the corresponding Learning Objective from the Chapter Opener. How is a fault different from a joint? (D)

A fault is a fracture or discontinuity in a rock mass along which movement or displacement occurs. This movement can be horizontal, vertical or both, and it results from tectonic forces acting on the Earth's crust.

A joint, on the other hand, is a fracture or break in a rock mass where there is no significant movement or displacement along the fracture. Joints can form due to various processes, such as cooling and contraction in igneous rocks, unloading or release of overburden pressure in sedimentary rocks, or folding and deformation in metamorphic rocks.

There are two main differences between a fault and a joint: 1. Movement and Displacement: The primary difference between a fault and a joint is the presence of movement or displacement along the fracture. In a fault, there is significant movement of the rock masses on either side of the fracture, whereas in a joint, there is no significant movement or displacement. 2. Formation Processes: Faults are typically formed due to tectonic forces acting on the Earth's crust, causing stress and eventually leading to movement along the fracture. Joints can form from a variety of processes, such as cooling and contraction, unloading, or deformation. In conclusion, a fault is a fracture in a rock mass with movement or displacement along the fracture, while a joint is a fracture without significant movement or displacement. Their formation processes also differ, with faults being primarily formed by tectonic forces and joints forming from various processes.