What is the difference between a joint and a fault?

What is the difference between a joint and a fault?

• A. A joint displaces rocks on one side relative to another.
• B. Rocks at a fault do not move.
• C. A joint forms when rocks slip past each other.
• D. A fault never involves movement.

Answer: (D)

The main idea is how a fracture behaves after it forms: does the rock on one side move relative to the other, or does it stay in place? Joints are cracks where the rock breaks but there is little or no movement along the crack. They form when the rock is stressed or cools and contracts, but the sides don’t slide past each other. Faults, on the other hand, are fractures along which blocks of rock have moved relative to one another. The movement along the fault plane can be up, down, sideways, or a combination, and this movement is what can cause earthquakes. So the difference is movement along the fracture: joints show essentially no displacement, faults show displacement. The statement that a joint displaces rocks on one side describes a fault, not a joint. The idea that rocks at a fault do not move is false. The idea that a joint forms when rocks slip past each other describes a fault, not a joint. And a fault never involving movement is also false.

The main idea is how a fracture behaves after it forms: does the rock on one side move relative to the other, or does it stay in place?

Joints are cracks where the rock breaks but there is little or no movement along the crack. They form when the rock is stressed or cools and contracts, but the sides don’t slide past each other.

Faults, on the other hand, are fractures along which blocks of rock have moved relative to one another. The movement along the fault plane can be up, down, sideways, or a combination, and this movement is what can cause earthquakes.

So the difference is movement along the fracture: joints show essentially no displacement, faults show displacement. The statement that a joint displaces rocks on one side describes a fault, not a joint. The idea that rocks at a fault do not move is false. The idea that a joint forms when rocks slip past each other describes a fault, not a joint. And a fault never involving movement is also false.