AC

Folding and Faulting - Summary Notes

Endogenic Processes

  • Endogenic processes are formed, located, or occurring beneath the Earth's surface.
  • Driven by energy from within the Earth (e.g., volcanism, earthquakes, folding, faulting).

Folds

  • Folds occur when the Earth’s crust bends due to compressional forces.
  • Types of folds:
    • Symmetrical: Limbs are the same due to equal compression; axial plane is vertical.
    • Asymmetrical: One limb is steeper due to unequal compression; axial plane is tilted.
    • Tight Fold: Sharp-peaked anticline or syncline due to greater compression.
    • Overfold: Rock becomes bent or warped, sometimes overlapping.
    • Recumbent Fold: Compressed so much it is no longer vertical, with significant overlapping.
    • Overthrust Fold: Fold fractures where the axis is pushed over, creating a fracture.
    • Nappe Fold: Extremely overturned, leading to fractured rock layers.
  • Parts of a fold:
    • Anticline: Crest of the fold.
    • Syncline: Trough of the fold.
    • Limb (Flank): Sloping side from crest to trough.
    • Axial Plane: Imaginary plane bisecting the vertical angle between equal slopes.
    • Axis: Line that divides the section of the fold.

Faults

  • Faults occur when tension, compression, and lateral tears from plate movement cause rock to fracture and displace.
  • Types of Faults:
    • Normal Fault: Rocks move away from each other.
    • Reverse Fault: Rocks compress, one plate moves up, the other descends.
    • Tear Fault: (Transform or Strike-Slip Fault): Tectonic plates slide laterally past each other.

Rift Valley (Garben)

  • Formed when two normal faults occur parallel to each other, and the land sinks between the faults.

Horst Fault (Block Mountain)

  • Land between parallel faults is forced upward because the faults are pushed together.

Importance of Folded and Faulted Landscapes

  • Tourism, waterfalls and reservoirs, natural boundaries, defensive sites, biodiversity, geothermal energy, watersheds.