Final answer:
When a solid rock deforms but returns to its original shape once the stress is removed, it has experienced elastic deformation. This occurs because the applied stress does not exceed the rock's elastic limit, allowing it to revert back to its initial form after being deformed.
Step-by-step explanation:
When solid rock deforms and then returns to its original shape without breaking, it has undergone elastic deformation.
Elastic deformation occurs when the stress applied to a rock does not exceed its elastic limit. If stress is applied to a rock and it deforms, but then goes back to its original shape after the stress is removed, this behavior is known as elasticity. Rocks undergoing this kind of deformation behave in the same way as elastic materials, which can stretch and then return to their original shape.
An important distinction between elastic and plastic deformation is that, with plastic deformation, the rock does not revert to its original form once the stress is relieved, instead retaining a permanent change in shape. This occurs when stress surpasses the elastic limit, and the rock begins to behave plastically. Liquefaction refers to a process where solid materials behave like liquids, clearly differing from elastic behavior, and brittle fracture describes a sudden break or crack in a material as a result of stress exceeding the strength of the material.