Interior of the Earth
Geophysicists use indirect evidence, primarily seismic waves, to explore the inaccessible interior of the Earth. This chapter details the physical and chemical properties of the Crust, Mantle, and Core.
Learning Objectives
- •Interpret seismic wave data to understand Earth's layering
- •Contrast the physical states of the Asthenosphere and Lithosphere
- •Classify types of volcanoes and intrusive igneous landforms
- •Identify the major seismic discontinuities
Key Concepts
Seismic Shadows
The S-wave shadow zone (beyond 103°) confirms the outer core is liquid. The P-wave shadow zone (103°-142°) is caused by refraction at the core-mantle boundary.
Internal Composition
The Crust (Continental & Oceanic) is brittle. The Mantle (84% of volume) is solid but convective. The Core is metallic, with a liquid outer layer and solid inner center.
Terminology
Historical Insight
Shield Volcanoes
Low-viscosity basaltic eruptions forming broad, gentle slopes, exemplified by Mauna Loa in Hawaii.
Quick Check
Why can't S-waves travel through the Core?
What is the 'Moho' discontinuity?
How to use this lesson
Read the overview first, then explain the main idea in your own words before checking the key concepts. Use the quick-check questions without looking at the answer. For examination preparation, verify dates, definitions, and syllabus requirements against your official textbook and school or examination-board guidance.
Test Your Knowledge
Ready to check your understanding of this chapter? Take our interactive practice quiz.