extrusive igneous activity
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Unit 4: Geographical Unit 4: Geographical ResearchResearch
Tectonic Activity and HazardsTectonic Activity and Hazards
What are these? Where are they? How did they get there?
Tectonic landscapes Tectonic landscapes
Lesson 7: What are the landscape Lesson 7: What are the landscape impact of extrusive igneous impact of extrusive igneous
activity? activity? Learning objectivesLearning objectivesTo outline the formation of extrusive To outline the formation of extrusive
igneous landforms such as lava igneous landforms such as lava plateaus and volcanoesplateaus and volcanoes
To investigate the different types of To investigate the different types of volcanoes and eruptionsvolcanoes and eruptions
Extrusive igneous activityExtrusive igneous activity Once extruded onto the surface of the Once extruded onto the surface of the
earth, magma is referred to as earth, magma is referred to as lavalava which which cools to form igneous rockscools to form igneous rocks
The most significant landforms are The most significant landforms are lava lava plateaus and volcanoesplateaus and volcanoes
Their distribution is determined by the Their distribution is determined by the pattern of tectonic platespattern of tectonic plates
Their impact on the landscape with vary Their impact on the landscape with vary according to the according to the magnitude and scale magnitude and scale of the of the events causing them and the events causing them and the types of types of material material being extruded. being extruded.
Lava PlateauLava Plateau
The Deccan PlateauThe Deccan Plateau
VolcanoesVolcanoes
Types of volcanoesTypes of volcanoes
Types of volcanoTypes of volcano
The type of volcano will be affected The type of volcano will be affected by:by:The type of lava eruptedThe type of lava eruptedThe nature of the eruptionThe nature of the eruptionThe type of plate marginThe type of plate margin
Magma type & volcano morphologyMagma type & volcano morphology
BasalticBasaltic – huge, low relief – huge, low relief shield volcanoesshield volcanoes plus small plus small scoria cones and fissure ventsscoria cones and fissure vents..
AndesiticAndesitic – steep sided – steep sided strato-volcanoesstrato-volcanoes; ; layers of lava, ash and tephra.layers of lava, ash and tephra.
RhyoliticRhyolitic – central craters with – central craters with lava plugs / lava plugs / domesdomes, due to high viscosity of the lava., due to high viscosity of the lava.
Types of volcanoTypes of volcanoDivergent marginsDivergent margins Fissure eruptions and Fissure eruptions and
shield volcanoesshield volcanoes Low, gently sloping Low, gently sloping
sides, wide basesides, wide base Basaltic lava, low Basaltic lava, low
viscosity, high temp so viscosity, high temp so covers long distances covers long distances before it cools and before it cools and solidifiessolidifies
Frequent, low Frequent, low magnitude eruptionsmagnitude eruptions
Also found at Also found at hotspotshotspots
Convergent marginsConvergent margins Cone shapedCone shaped Less frequent, more Less frequent, more
explosive eruptionsexplosive eruptions More silica and cooler, More silica and cooler,
so more viscousso more viscous Flows slowly, cools Flows slowly, cools
quickly creating cone quickly creating cone shape with narrow base shape with narrow base and greater heightand greater height
Often composite with Often composite with alternating layers of ash alternating layers of ash and lavaand lava
Watch video
Hawaii – shield volcanoesHawaii – shield volcanoes
Oceanic hotspot location
Volcanoes formed by tectonic plate moving north west over hotspot
Gently sloping sides
New volcano, 3000m tall and 2000m below sea
Soufriere Hills, Montserrat – Soufriere Hills, Montserrat – Composite volcanoComposite volcano
Volcano type Diagram Key features Explanation Example
Fissure
Shield
Dome
Cinder
Composite
Caldera
Wherever possible, try to use examples we have already used e.g. Kiluaea, Montserrat, Yellowstone
Types of eruptionTypes of eruption
Hawaiin – calm, non explosiveHawaiin – calm, non explosiveVulcanian – explosive, short livedVulcanian – explosive, short lived
What type of eruption is associated What type of eruption is associated with your case studies? Why? What with your case studies? Why? What impact has this had? Add this to the impact has this had? Add this to the explanation column on your tableexplanation column on your table
Suggested resourcesSuggested resourcesRead pages 253-255 OUP text bookRead pages 253-255 OUP text bookPages 162-165 Byrne et alPages 162-165 Byrne et alPage 67 Frampton et alPage 67 Frampton et alPage 14-15 NaglePage 14-15 NaglePage 22-26 WaughPage 22-26 WaughNational geographic “Forces of nature” National geographic “Forces of nature”
– see types of volcano link on Moodle– see types of volcano link on MoodleExplore google earth locationsExplore google earth locations
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Intrusive igneous landformsIntrusive igneous landforms