ZIMSEC O Level Geography Notes: Faulting.
- Lateral earth movements often produce very great stresses due to compressional forces (when plates move towards one another) and tensional forces (pulling apart).
- These forces can cause fractures or breaks in the earth’s crust.
- When breaks occur in the earth’s crust where no rocks are displaced the breaks are called joints.
- If the rocks are displaced on both or either side of the crack it is called a fault.
- Faulting refers to the fracturing or breaking of the earth’s crust due to both compression and tension forces as a result of the tectonic movements.
- Faulting normally displaces the crustal block along lines.
- The end result is that rocks are either heaved (pushed) above or dropped below the general level of land.
Features of a simple fault
- Heave-the forward horizontal displacement of the sediments.
- Throw-the vertical displacement of the sediments or strata (layer).
- When rocks are folded and tilted they do so in many ways and the following terms are used to describe these tilts.
- Dip-refers to the direction the sediment tilts in.
- Bedding plane-refers to the surface or plane that separates one sediment layer from another. This is normally a line that follows the weaknesses between sediments (layers) of different compositions.
Types of faults
- There are several types of faults viz:
- Normal faults
- Reverse faults.
- Tear fault
1 Normal faults
- Is caused by tension forces which cause part of the earth to move downwards.
- That is the central block (the one to the right in the picture, not shown in the picture is a fault plane to the right of the central block) is displaced downwards.
2. Reverse fault.
- Are caused by compressional forces i.e pushing towards each other.
- When rocks are subjected to compression the central block is forced upwards (heaved upwards) relative to the level ground and adjoining blocks.
- That is the central block (the one to the right in the picture) is displaced upwards.
3. The Tear fault.
Quick NetOne, Telecel, Africom, And Econet Airtime Recharge
If anything goes wrong, click here to enter your query.