What happens to rocks after their elastic limit is passed?
When a rock is subjected to stress, it undergoes deformation. Initially, it exhibits elastic deformation, where it returns to its original shape when the stress is removed. However, if the applied stress exceeds the rock's elastic limit, permanent or plastic deformation occurs. The rock will undergo an irreversible change in shape and will not completely return to its original form.
To determine what specifically happens to rocks after their elastic limit is passed, we need to consider the type of rock and the specific conditions. Here are two common outcomes:
1. Fracture: Rocks can fracture or break when their elastic limit is exceeded. This can result in the formation of cracks, joints, or faults within the rock. Fracturing can occur due to the propagation of pre-existing weaknesses within the rock, such as bedding planes or mineral veins, or due to the creation of new fractures.
2. Flow and Shearing: In some cases, rather than fracturing, rocks can flow or undergo shearing deformation when their elastic limit is surpassed. This typically happens in rocks that are ductile, meaning they can be deformed without breaking. During flow or shearing, the rock's shape is permanently altered, often resulting in folding, faulting, or other structural changes.
Determining the specific response of a rock after its elastic limit is passed requires a combination of experimental testing, theoretical modeling, and geological observation. Scientists and geologists employ techniques such as laboratory experiments, field observations, and computer simulations to study rock behavior and understand how they respond to stress.