1. On which plate boundary is Ireland located? 2. What does the term ‘subduction’ mean? 3. What is an ocean trench? 4. List three types of convergent plate boundary. 5. Name two plates separating from each other at the Mid-Atlantic Ridge.
EXAM LINK (HL) Plate Boundaries (30 marks)
‘Plate boundaries are places where land is both created and destroyed.’ Examine this statement, with reference to examples you have studied.
2007, Q1B
CASE STUDY: IMPACT OF TECTONIC ACTIVITY ON THE IRISH LANDSCAPE
The impact of millions of years of plate tectonic activity can be observed in our natural landscape today.
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Around 850 mya, Ireland was divided into two sections (Fig. 1.12(a)). ƒzNorth-west Ireland existed as part of the North American Plate, just south of the equator.
ƒzSouth-east Ireland existed over 60° south of the equator as part of a landmass which also contained England and Wales.
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400 mya, the two landmasses merged about 20° south of the equator. The collision of the two landmasses led to: ƒzthe closure of the Lapetus Sea, which had separated the two landmasses. A scar on the landscape stretching from Clogherhead (Co. Louth) on the east coast to Dingle (Co. Kerry) on the west coast marks the line where the two landmasses merged;
ƒzthe formation of the Caledonian fold mountain range. This range has a south-west to north-east directional trend, reflecting the line along which the plates collided;
ƒzfaulting in the north of the country, with the various fault lines also taking south-west to north-east directional trends;
ƒzvolcanic activity, which resulted in the formation of granite in the Leinster Batholith.
Fig. 1.12(a) Ireland approximately 850 mya. mya = million years ago equator NW Ireland 30° S SE Ireland Marking Scheme: Name one constructive and one destructive plate boundary = 2 × 2 marks
Discussion regarding both creation and destruction = 7 SRPs × 2 marks (creation or destruction) + 6 SRPs × 2 marks (destruction or creation)
6. Name a volcanic island formed at the Mid- Atlantic Ridge.
7. How has Mt. Kilimanjaro been formed? 8. What happens at a transform plate boundary? 9. Why are earthquakes so violent at the San Andreas Fault?
