Define Faulting. Describe major types of faults and the resultant landforms.

 Define Faulting. Describe major types of faults and the resultant landforms.

Approach:

  • Explain what is faulting
  • Describe major types of faults
  • Explain landforms due to faulting
  • Conclude with importance of faulting
Model Answer :

When the crustal rocks are displaced due to movement caused by the endogenetic forces along a plane, the resultant structure is called a fault and the process is known as faulting. The plane along which the rocks blocks are displaced is called fault plane. A fault may be vertical, inclined, horizontal or any of type and form. The movement responsible for the formation of a fault may operate in vertical or horizontal or in any direction.

Types of Fault:

The different types of faulting of the crustal rocks are determined by the direction of motion along the fracture plane. Based on this several types of faults have been recognised by the geologists:

  1. Normal Fault: These faults developed mainly due to the vertical movements that occur as the rocks are pulled apart due to tensional force. When two normal faults occur, the narrow block that dropps down between them is a graben, and elevated region is a horst. The horsts make block-like plateaus or mountains often with flat top but steep sides.
  1. Reverse Fault: The Reverse faults are formed due to the movement of both the fractured rock blocks towards each other. On account of extreme compression rocks snap and one stratum is pushed over the underlying stratum.
  2. Lateral Fault or Strike-slip fault: A lateral fault is formed when the rock blocks are displaced horizontally along the fault plane due to horizontal movement. They are the result of Shear stresses in the crust.

Landforms Associated with Faulting:

  1. Block Mountains: These Mountains are formed when great blocks of the earth crust may be raised or lowered due to normal faulting. For example: Black forest in Germany and Ruwnzori in Uganda.
  2. Rift Valley: It is a trough or basin, formed due to displacement of crustal parts and subsidence of middle portion between two normal faults. For example: East African rift valley and Narmada rift valley.
  3. Plateaus and Basins: These are the result of wrapping of the earth crust. Uplifted area due to wrapping are called plateaus for e.g. Deccan Plateau (India) and depressed areas due to wrapping are called basins for e.g. Victoria Basin (Africa).

Faulting has not only geomorphological importance but it also have great socio-economic significance. For e.g. petroleum deposits are found in porous sedimentary rocks that have been faulted against impervious shale beds.

Subjects : Geography – Physical

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