LC Geography Answer Structure

Chapter 1: Plate Tectonics


“Discuss the impact of destructive plate boundaries with reference to examples you’ve studied”

  1. Intro

  2. Oceanic-Continental (Eurasian and Pacific) Japanese trench, Japanese islands

  •       Plates collide and heavier plate subducts (formation of ocean trench)

  •      Subducted plate’s crust melts in the mantle making magma rise and cause       eruptions.

  •       Lava that’s surfaced melts into rock that makes new land (volcanic island arc)

  1. Continental-Continental (Eurasian and African) The Alps, Fold mountains

  •        Subduction doesn’t happen since both plates are less dense than the mantle,        instead, they buckle up and make fold mountains.

  •      Fold mountains are composed of sedimentary rock formed on seabed and fossils        of marine creatures are found above sea level.

  •      Colliding continental plates move sideways and up making shallow, strong             earthquakes.

  1. Oceanic-Oceanic (Pacific and Philippine) Mariana trench, Mariana Islands

  •      The plate that’s heavier or moving faster is subducted beneath the other plate,        making a subduction zone.

  •      Deep ocean trenches (definition), mark the subduction zone. (Mariana Trench,        over 11km deep)

  •      Island arc (definition). Plate is melted and magma rises to form underwater             volcanoes. They appear on the surface as islands (Philippine and Japanese        Islands).


“Examine how tectonic activity has influenced the development of Irish landscape”

  1. Intro

  •     Earth’s crust is divided into tectonic plates, which float on semi-molten rock in     upper mantle.

  •     Plate moves as convection currents cause them to move, causing them to collide,     separate and slide (destructive, constructive, transform boundary).

  1. Antrim-Derry Plateau

  •    A basalt plateau is a large, flat topped upland area made of basalt. It forms on    constructive plate boundaries.

  •    Constructive boundaries form by plates pulled apart by tensional forces via    convection currents, causing splits (faults) and steep valleys (rift valleys) to form.

  •    Pressure on the mantle is reduced as magma makes its way along the fissures to    the surface. Basic magma (low silica), erupts and spreads out evenly.

  •    Over millions of years, repeated fissure eruptions built up layers of basalt rock,    leading to the formation of a basalt plateau.

  •    65mya, Ireland had a lot of volcanic activity as Eurasian and North American plates    pulled apart, creating the Atlantic Ocean.

  •    The pulling apart of tectonic plates made a rift valley with large fissure. Pressure    was reduced as basic lava surfaced. Lava poured evenly through fissures in    successive flows — around 5-6 metres each. Volcanic activity lasted for 15 million    years.

  •    The Antrim-Derry Plateau’s 350m in height and 4000km². There was 3 periods of    activity resulting in lower, middle and upper basalt.

  •    The middle basalt forms the Giant’s Causeway, the polygonal columns formed due    to variations on cooling rates.

  1. Leinster Batholith

  •     A batholith’s formed when magma’s pushed up from mantle to the crust above.    Magma cools and solidifies slowly over millions of years to make a dome-shaped    block of granite.

  •     As the magma cools it heats and melts surrounding rock, metamorphosing them.

  •    The Leinster Batholith was formed 400mya during the Caledonian period. The     North and Eurasian plates were colliding causing layers of sedimentary rock to     buckle upwards, forming the Leinster fold mountains.

  •     The heat and pressure from the magma caused metamorphism to the sedimentary     rock surrounding. Sandstone was changed to quartzite which is seen in the     Wicklow Mountains.

  •     Denudation removed the overlying rock layers over millions of years. It exposed the     granite of the Leinster Batholith (Kippure, Co. Wicklow).

  •     The Leinster batholith is the largest in Ireland and UK. It stretches 120km from     Dublin-Kilkenny and covers 1500km². It spans through mountains ranges like the     Wicklow mountains.

  1. Armorican Fold Mountains (Optional)


“Discuss the theory of plate tectonics”

  1. Intro

  •      The Theory of Plate Tectonics explains the forces working along crustal boundaries.

  •    The Theory of Plate Tectonics is split into:

    • Theory of Continental Drift (Alfred Wegener — 1912).

    • Sea Floor Spreading (Harry H. Hess — 1960).

  1. Continental Drift (Pangaea, Alfred Wegner — 1912)

  •    Alfred Wegener proposed the Theory of Continental Drift in 1912.

  •    He proposed that the Earth’s continents were together and they’d drifted apart from    a supercontinent (Pangaea 200mya). He believed Pangaea split into    Gondwanaland and Laurasia and then into their present places.

  •    Wegener supported his theories with:

    • Matching Coastlines and rock types: Some of the coastlines fit together perfectly such as the east coast of South America and West coast of Africa.

    • Matching Mountain Ranges: The Appalachian mountain range along the east coast of the US and the Caledonian in Northern Ireland, Scotland and Scandinavia formed a line when joined.

  1. Sea-floor Spreading (Mid-Atlantic Ridge, Harry H. Hess — 1960)

  2. Plate Tectonics (Combine theories, Vine and Matthews — 1968)


“Discuss with examples you’ve studied, how plate tectonics help us to understand the forces of work along crustal plate boundaries”.

  1. Intro

  2. Constructive plate boundaries (O-C, O-O, C-C)

  3. Destructive plate boundaries (O-C, O-O, C-C)

  4. Transform plate boundaries


“Explain how the study of plate tectonics has helped us to understand the global distribution of volcanoes”

  1. Intro

  • Earth’s crust is divided into tectonic plates, which float on semi-molten rock in     upper mantle.

  •     Plate moves as convection currents cause them to move, causing them to collide,     separate and slide (destructive, constructive, transform boundary).

  1. Destructive Plate boundaries

  2. Constructive Plate boundaries

  3. Hotspots


“Examine the influence of volcanic activity on the development of the Irish landscape on intrusive and extrusive features”

  1. Intro

  2. Batholith (Intrusive)

  3. Basalt Plateau (Extrusive)


“Examine how the occurring of volcanic activity can be predicted and their effects reduced”

  1. Intro

  2. Seismic Activity

  3. Gas emissions

  4. Ground deformation


“Examine the causes and effects of a volcano that you’ve studied”

  1. Intro

  2. Loss of life

  3. Loss of infrastructure

  4. Homelessness


“Discuss the positive and/or negative impacts of Volcanic Activity”

  1. Intro

  2. Positive effects

    1. Geothermal Energy

    2. Fertile soils

    3. Tourism

  3. Negative effects

    1. Lahar

    2. Damages

    3. Loss of life