footwall
Noun: 1. The lower wall of an inclined fault: In geology, the 'footwall' is the mass of rock that lies beneath an inclined fault plane. If you imagine standing on the fault line, the footwall is the block under your feet.
The term 'footwall' is a technical term used almost exclusively in geology and mining to describe structural relationships in rock formations, particularly faults. - It is used to specify the relative position of rock blocks. - It is often discussed in contrast with the 'hanging wall', which is the rock mass above the fault plane.
- Noun:
- Miners extracted ore from the rich vein in the footwall of the fault.
- The geologist explained that the earthquake caused the footwall to move upward relative to the hanging wall.
- In a normal fault, the footwall moves up relative to the hanging wall.
- "Footwall block": A synonymous term emphasizing the footwall as a discrete structural unit.
- The footwall block of the thrust fault contained older sedimentary layers.
- "Footwall rocks": Refers to the specific rock types that make up the footwall.
- The footwall rocks were heavily fractured and altered.
- Hanging wall (n): The rock mass that lies above an inclined fault plane. This is the direct counterpart to the footwall.
- Fault (n): A fracture or zone of fractures between two blocks of rock.
- Fault plane (n): The planar surface along which dislocation occurs during fault movement.
- Lower wall: A less common, descriptive synonym.
- Subjacent block: A formal technical synonym meaning the underlying block.
The concept relies entirely on the geometry of an inclined fault. The 'footwall' is not defined by the type of fault (normal, reverse, thrust) but by its position below the fault plane. Its movement (up or down) defines the fault type.
- the lower wall of an inclined fault