Final answer:
Rocks undergoing plastic deformation exhibit a permanent change in shape that does not revert back once stress is removed, commonly leading to the formation of metamorphic rocks from the alteration of protoliths under various conditions.
Step-by-step explanation:
Rocks undergoing plastic deformation exhibit a permanent deformation. When rocks are subjected to stress that exceeds their elastic limit, they go through what is known as plastic deformation. Unlike elastic behavior where rocks can return to their original shape, rocks that deform plastically do not revert back after stress is removed. This process can lead to the bending of rocks into folds or even fracturing in a brittle manner. Metamorphic rocks are a type of rock that forms from the alteration of the mineral content and texture of a protolith (parent rock) due to factors such as the change in temperature, pressure, or exposure to chemically reactive fluids.
The deformation and creation of metamorphic rocks are integral to understanding geological processes. At larger depths, rocks tend to deform in a more plastic manner, and near the Earth's surface, they are more likely to fracture in a brittle way. The study of these processes helps geologists decipher the complex history of Earth's geology and the dynamic forces shaping it.