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Chapter 2

ESS105H1 Chapter Notes - Chapter 2: Continental Crust, Seafloor Spreading, Outer Core

Earth Sciences
Course Code
Lisa Tutty

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Chapter 2: Earth Systems Processes and Interactions
2.1 The Solid Earth System: Components and Processes
- The inner core is made of solid iron and nickel; outer core is molten and responsible for
Earth’s magnetic field
- The mantle surrounds the core and exhibits a caramel/taffy flow texture
- Rocks in the mantle deform slowly due to the high temperature and pressure; however,
the high pressure keeps the rocks from becoming molten
- The crust can be split into seafloor/oceanic crust and continental crust
- Crust and uppermost mantle make up the lithosphere; lithosphere is quite thin and
consists of plates which move over the uppermost portion of the mantle; lithosphere is
above the asthenosphere
- Plates move via seafloor spreading; convection cells bring hot mantle rock towards
Earth’s surface
- Mid-ocean ridges are evidence of ocean crust formation
- The heat within Earth is generated by radioactive decay
- Subduction creates seafloor trenches; as the plate subducts, magma is formed which in
turn results in volcanoes
- When large amounts of magma move under a continent, plates are rifted apart
- Large magma sources result from magma plumes; they originate deep within the mantle
2.2 Rock Cycle
2.2.1 Igneous Rocks
- Intrusive igneous rocks form below Earth’s surface
- Plutons: bodies of solidified magma beneath Earth’s surface
- Most continental crust is composed of granite (coarse grained)
- Extrusive igneous rocks form at Earth’s surface
- Oceanic crust is normally made of basalt (fine-grained)
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