Other structures Tectonic forces also formed some other rock structures of the Irish landscape.
Dome structures
When layers of rocks arch upward to form a circular type structure it is referred to as a dome. They can be formed in one of two ways: zz
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when compressional force is exerted on a plate; when rising magma raises rock upwards.
The oldest rocks become exposed at the centre of the dome when it is worn down by years of denudation. Dome structures formed in Ireland include the Slieve Bloom Mountains in Laois and Offaly.
Horizontal structures
Some rock structures are gently uplifted without any tilting, folding or faulting taking place. This can be recognised in sedimentary rock structures where the strata remain in a horizontal line such as Loop Head, County Clare.
Uniclinal structures
Some rock structures are uplifted on one side more than the other. This can be seen on Ben Bulben in County Sligo, where a slight tilt on the uplifted landscape is clearly visible (Fig. 4.13).
Fig. 4.13 Ben Bulbin. CHECK YOUR LEARNING
1. List each of the forces that result in faulting. 2. In which rock structures are faults most easily recognised?
3. A normal fault is formed at which type of plate boundary?
4. A reverse fault is formed at which type of plate boundary?
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5. What is another name for a block mountain? 6. What two plates are associated with the San Andreas Fault?
7. Why are earthquakes so severe in California? 8. How are dome structures formed?
