The forces responsible for altering the Earth’s surface configuration are referred to as Geomorphic Processes.

Types of Geomorphic Processes

1. Endogenic Processes:
   These are internal forces within the Earth that create landforms. They are considered constructive as they lead to the formation of relief features such as mountains.

• Energy Source: Convective currents generated inside the Earth.
• Categories of Endogenic Processes:
  • Sudden Movements: Includes phenomena like earthquakes and volcanic eruptions.
  • Slow Movements (Diastrophic Forces): These processes contribute to the formation of continents, mountains, and other large-scale surface features.

Types of Diastrophic Movements

• Epeirogenic Movement:
  • Vertical in nature.
  • Causes upliftment or subsidence of large areas.
  • Responsible for the formation of continents.
• Orogenic Movement:
  • Horizontal in nature.
  • Involves forces like compression and tension.
  • Leads to processes like folding, faulting, and mountain building.

Folds in Geology

Folds are wavy undulations formed when crustal rocks are subjected to compressional forces caused by horizontal plate movements.

Types of Folds

1. Symmetrical Fold: The axial plane is vertical, and both limbs incline evenly.
2. Asymmetrical Fold: The axial plane is tilted, and the limbs dip in opposite directions.
3. Overturned Fold: The axial plane is inclined, and both limbs dip in the same direction but at different angles.
4. Isoclinal Fold: Both limbs dip at the same angle in the same direction.
5. Recumbent Fold: Characterized by a horizontal axial plane.
6. Chevron Fold: Features sharp, angular crests and troughs.
7. Fan Fold: The limbs are so extensively overturned that the fold resembles a fan.
8. Open Fold: The angle between the limbs is greater than 90° but less than 180°.
9. Closed Fold: The angle between the limbs is less than 90°.
10. Nappe: Formed by intense horizontal compression, these folds originate from recumbent folds.
11. Anticlinorium: A large anticline with minor anticlines and synclines within it.
12. Synclinorium: A large syncline containing minor folds within it.

Faults in Geology

Faults refer to fractures or cracks in the Earth’s crust where displacement of rocks occurs parallel to the fault plane. These movements are caused by tensional, compressional, or combined forces acting horizontally or vertically.

Types of Faults

1. Normal Fault: Results from tensional forces that pull the crust apart.
2. Reverse Fault: Caused by compressional forces, where blocks move towards each other.
3. Strike-Slip Fault: Occurs when rock masses slide past each other parallel to the fault’s strike.
4. Transform Fault: A specific type of strike-slip fault seen at transform plate boundaries, such as the Dead Sea Transform Fault.

Graben and Horst

• Graben (Rift Valley): A trench-like depression with parallel walls, formed when a block of rock subsides between two normal faults.
• Horst: A raised block with steep sides, created when a section of rock is uplifted between two normal faults.

Example: Horsts and Grabens are prominent in the East African Rift Valley.

Rifting: The process where a single tectonic plate breaks into multiple plates, leading to the formation of divergent plate boundaries.