The University of Zambia
School of Education
LSE 3069: Fundamental Topics in Secondary School
Compiled
By
K.Mundende
2020
Faulting
• Fracturing or breaking of the rocks within the earths crust
• Associated with either lateral or vertical earth movements
• Associated with movement of the rock blocks
• Rocks that fracture are usually brittle and compact, which may
fracture or break whenever they are subjected to either tensional or
compressional forces
• Tensional or compressional forces might be as a result of tectonic
movements (Movement of plates that make up Earth’s crust or causing
deformation of Earth’s crust)
Cont’d
• Fracture on a rock that is caused by earth movements is known as a
fault
• Fault refers to a fracture in the crust due to stress or strain associated
with rock displacement
• Joint is a crack in the rock due to stress or strain but not associated
with rock displacement
Factors influencing development of a Fault
• Nature of the force involved (Tensional or compressional)
• Nature of the rocks on which the force acts (Brittle or soft)
Types of Faults
Normal Fault: Develops when the brittle, hard but breakable rocks
are subjected to tensional forces.
Cont’d
• Include faults in which the inclination of the fault planes and the down
throw are on the same side.
• Footwall rises while the hanging wall goes down
• A throw is a vertical displacement of the faulted blocks. Blocks can
either be displaced upwards (up-throw) or down wards (down – throw)
• Hanging wall is a steep slope on the up-throw that faces the downthrow
• Floor is the plain ground on the down -throw
Cont’d
• Reverse Fault: Develops when brittle rocks are subjected to
compressional forces.
Cont’d
• The inclination and the down throw are not on the same side
• The foot wall subsides while the hanging wall rises above the foot wall
Cont’d
• Tear/Shear/Slip/Transform Fault: Develops when brittle rocks are
subjected to compressional forces
• Blocks slide past each other in a shear manner, like a pair of scissors
Cont’d
• Also called wrench fault
• Vertical fracture produced when two rock blocks slide against one
another
Cont’d
• Step Fault: Develop on brittle rocks which have been subjected to
several tensional forces
• Rocks may sink at different levels to form fault steps
Cont’d
• Three main types of fault in motion during the development of step
fault are:
Normal fault
Reverse fault
Strike slip fault
Features Developed through Faulting
• Fault blocks(Block Mountains)
• Rift valley
• Till blocks
• Plateaus
• Escarpments (Fault scarps)
Activity
• With the aid of an annotated diagram, explain the development of:
(i) An over thrust Fault
(ii) Monocline Fault
References
• Kinunda, E.J. and Msabila, T.D. (2012). The Comprehensive Approach
to Ordinary Level: Geography. Dar es Salaam: Nyambari Nyangwine
Publishers
• Yogo, J.M. (2012). Ordinary Level Physical Geography. Dar es
Salaam: Nyambari Nyangwine Publishers