Final answer:
When solid rock deforms and quickly returns to its original shape, it has undergone elastic deformation. Elastic deformation occurs when rocks behave in an elastic manner and return to their original shape after deformation.
Step-by-step explanation:
When solid rock deforms and then quickly returns to its original shape, it has undergone elastic deformation. Elastic deformation occurs when rocks behave in an elastic manner and return to their original shape after deformation. It continues until rocks reach their elastic limit, beyond which plastic deformation occurs and rocks do not return to their original shape.