Final answer:
A rock that returns to its original shape after stress is removed is exhibiting elastic behavior. Elastic deformation happens within the elastic limit, beyond which rocks will not regain their original shape and instead deform plastically or fracture.
Step-by-step explanation:
A rock that has undergone a change in shape as a result of applied stress but will return to its original shape after the stress has been removed is said to be elastic. Elasticity is the property of solid objects and materials to resume their normal shape after being subjected to deformational forces. When stress is applied to rocks, they initially exhibit elastic deformation, which allows them to return to their original shape.
This property is due to the microscopic structure of the material, such as the stretching of polymer chains in rubbers or the resizing and reshaping of crystalline cells in metals. Beyond the elastic limit, rocks experience plastic deformation or fracture and do not regain their original shape after stress is released. Therefore, within the Earth's crust, different conditions such as stress type, rock type, depth, pressure, and temperature can influence whether rocks will behave in an elastic, plastic, or brittle manner when exposed to stress.