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Chapter 2
CHAPTER 2
THE EARTH IN SPACE AND
TIME
© Oxford University Press, 2008. All rights reserved.
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Chapter 2
THE EARTH IN SPACE
• Our galaxy – the Milky Way
• Our solar system – the Sun and 9
planets
• Earth’s elliptical orbit around the Sun
• Equinoxes and solstices
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Chapter 2
THE EARTH IN TIME
• Meteorites and the Earth
• The age of the Earth
• The Earth’s atmosphere
• Geological time scales
• Life on Earth
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Chapter 2
PROPERTIES OF THE
EARTH
• Determining the nature of the Earth
• Density of the Earth
• Magnetic fields and palaeomagnetism
• Earthquakes
• The Earth’s interior
• The Earth’s crust
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Chapter 2
PLATE TECTONICS
• Continental crust
• Oceanic crust
• Lithospheric plates and ‘continental drift’
• Plate boundaries
– Diverging plate boundaries
– Transform fault boundaries
– Convergent boundaries (collision, subduction)
• Subduction boundaries and ocean trenches
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Chapter 2
VOLCANOES
• Present mainly along plate boundaries
– Convergent, e.g. Pacific Rim
– Divergent, e.g. sub-oceanic plates
(spreading-ridge magmatism)
– Within-plate volcanism : ‘hot spot’
mantle plumes (e.g. Hawaiian islands in
Pacific Ocean plate)
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Chapter 2
VOLCANOES – EFFECTS
• Lava flows, pyroclastics – boulders,
ash
• Fine dust to 20 km into atmosphere
• Gases and steam, including SO2,
CO2
• Ash cones or extensive lava flows
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Chapter 2
CONTINENTAL MARGINS
• Plate boundaries and continental margins
• Continental shelf
• Exogenic forces and sedimentation on
shelf
• Sediment ‘starvation’ (large dams) leads to
ocean encroachment
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Chapter 2
ISOSTACY
• Depth of compensation (asthenosphere), where materials
exert similar pressure
• Isostacy allows for reduction in stresses caused by variable
loads including:
– oceanic crusts thinner than continental crusts
– mountain-building leads to uneven thickening of continental
crusts
– continental-scale ice caps
– major sedimentation on continental margins, e.g. deltas
• Isostatic readjustment and sea levels
© Oxford University Press, 2008. All rights reserved.
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