Folding and Faulting Lecture Notes

Vocabulary flashcards covering the key terms, tectonic forces, and rock structures associated with folding and faulting processes.

Denudation

The breakdown of rock by weathering and erosion.

Fault line

A fracture in the earth’s surface.

Fault plane

The plane along which the faulted block of rock moves upwards or downwards.

Fault scarp

A step/cliff or cliff-like feature on the earth’s surface caused by faulting.

Tension

A tectonic force occurring where plates separate at divergent boundaries, causing rocks to lengthen through elasticity or break apart.

Compression

A tectonic force occurring where plates collide at convergent boundaries, causing rocks to be squeezed, shortened, or fractured.

Shearing

A tectonic force occurring at transform boundaries where plates slide past one another in opposite directions parallel to each other.

Simple (symmetrical) fold

A fold where limbs on either side have the same steepness and length due to equal pressure applied from both sides.

Asymmetrical fold

A fold where one limb is steeper and shorter than the other due to more pressure being applied from one side.

Alpine Folding

The last major mountain building period that peaked around $30$ million years ago, forming the Alps, Himalayas, Rockies, and Andes.

The Throw

The distance the crust has moved upwards or downwards during the faulting process.

The Heave

The horizontal movement of the rock along a fault.

Hanging wall

The section of the rock that slides along the fault plane.

Footwall

The section of the rock that does not move during the sliding process of a fault.

Graben fault

A fault formed by tension where a central block of crust sinks between two parallel faults, creating a rift valley.

Normal fault

A fault formed at divergent boundaries where tension causes the hanging wall to slide downwards, leaving the footwall elevated.

Transform Faults

Also known as tear faults, these occur when sections of the crust move sideways at transform plate boundaries.

East African Rift Valley

A $4,800\,km$ rift stretching from Syria to the Zambezi River that widens at a rate of $4\,mm$ per year.

Dome Structures

Circular structures formed when rock layers arch upward due to compressional force or rising magma raising the rock.

Horizontal structures

Sedimentary rock structures, such as those at Loop Head, County Clare, where strata remain in a horizontal line after gentle uplift without tilting.