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Questions and Answers
Which layer of the Earth is characterized as a viscous molten rock?
Which layer of the Earth is characterized as a viscous molten rock?
What is the average density of the Earth's crust?
What is the average density of the Earth's crust?
Which statement about oceanic and continental crust is true?
Which statement about oceanic and continental crust is true?
Which of the following elements is most abundant in the Earth's crust by weight?
Which of the following elements is most abundant in the Earth's crust by weight?
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What is the depth range of the continental crust in relation to major mountain systems?
What is the depth range of the continental crust in relation to major mountain systems?
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The term 'felsic' in geology refers to which type of rocks?
The term 'felsic' in geology refers to which type of rocks?
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What does the Mohorovicic (Moho) discontinuity signify?
What does the Mohorovicic (Moho) discontinuity signify?
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What is the temperature increase rate per kilometer in the upper part of the Earth's crust?
What is the temperature increase rate per kilometer in the upper part of the Earth's crust?
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Study Notes
Earth's Internal Structure
- Earth consists of concentric layers: crust, mantle, outer core, and inner core, each with distinct physical and chemical properties.
- Crust: silicate solid; Mantle: viscous molten rock; Outer Core: viscous liquid; Inner Core: dense solid.
- Earth's mechanical layers: lithosphere, asthenosphere, mesospheric mantle, outer core, and inner core.
- Chemical classification includes crust, upper mantle, lower mantle, outer core, and inner core.
Most Abundant Elements of the Earth's Crust
- Oxygen (46.6%), Silicon (27.7%), Aluminum (8.1%), Iron (5.0%), Calcium (3.6%), Sodium (2.8%), Potassium (2.6%), Magnesium (1.5%).
Most Abundant Elements of the Earth
- Iron (34.5%), Oxygen (29.5%), Silicon (15.2%), Magnesium (12.7%).
The Crust
- Outermost layer, comprising 0.5-1.0% of Earth's volume and <1% of its mass.
- Average density: ~2.7 g/cm³; density increases with depth.
- Oceanic crust thickness: 5-30 km; Continental crust thickness: 50-70 km, up to 70-100 km in mountain ranges like the Himalayas.
- Temperature ranges from 200 °C to 400 °C at the mantle boundary; temperature increases by ~30 °C per kilometer in the upper crust.
- Composed of sedimentary materials on top, with crystalline, igneous, and metamorphic rocks underneath; lower crust includes basaltic and ultra-basic rocks.
Composition of Crust
- Continental crust: lighter (felsic) sodium-potassium-aluminum silicate rocks, e.g., granite.
- Oceanic crust: denser (mafic) iron-magnesium-silicate igneous rocks, e.g., basalt.
- Felsic rocks are rich in silica, oxygen, aluminum, sodium, and potassium, contrasting with mafic rocks that have more magnesium and iron.
- Classification terms: sial (lighter continental materials) and sima (heavier oceanic materials) are now considered somewhat outdated.
The Mohorovicic (Moho) Discontinuity
- Marks the boundary between the Earth's crust and the underlying mantle, characterized by a transition in seismic activity and rock composition.
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Description
Test your knowledge on the internal structure of the Earth, including its layers such as the crust, mantle, outer core, and inner core. Explore the unique physical and chemical properties of these layers and learn about the most abundant elements in the Earth's crust.
