LEQ: What is and what are the parts of a fault?

• Lesson Key Terms: fault, hanging wall, footwall.

Faults• When the stress forces of compression, tension,

or shearing become to great on the rock slab, the rock slab may crack or break.

• Once the crack or break in the rock slab is created, as future stress forces build, the rock slabs will slip along the crack or break.

• The crack in the rock slab is known as a Fault.• By definition, a fault is a break in Earth’s crust where slabs

of rock slip past each other.

Fault line

Hanging WallThe block of rock that forms the upper half of a fault. Always ABOVE the fault line.

FootwallThe block of rock that forms the lower half of a fault. Always below the fault line.

Use the above diagram, and on your notes sheet, label the fault line, the hanging wall, and the footwall.

Diagram 1.

1. What type of stress (compression, tension, or shearing) is illustrated in Diagram 1 ? (hint: look at the arrows showing the direction of the force, and use your types of stress notes)

2. Which block (A or E) is the hanging wall of the fault ?3. Which block (A or E) is the footwall of the fault ?

Diagram 2.

1. What type of stress (compression, tension, or shearing) is illustrated in Diagram 2 ? (hint: look at the arrows showing the

direction of the force, and use your types of stress notes)

2. Which block (A or E) is the hanging wall of the fault ?3. Which block (A or E) is the footwall of the fault ?