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Earth’s Composition. Formation of Layers of Earth. OBSERVATIONS: The Earth is not uniform! The layers generally become denser with depth. THEORY: - PowerPoint PPT Presentation
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Earth’s Composition
Formation of Layers of Earth
OBSERVATIONS:• The Earth is not uniform!• The layers generally become denser with
depth.THEORY:• Scientists think that Earth was once molten
and denser materials settled towards the core and low-density materials floated to the surface. (all due to gravity)
Layers of the Earth
Boundaries that mark density changes between layers are discontinuities.Ex: Mohorovicic discontinuity separates the crust from the mantle.
Project Mohole• 1958-1966• Attempt to dig to Mohorovicic Discontinuity
How do we know information about Earth’s interior?
• Scientists have studied seismic waves.• P-waves (primary) are longitudinal and can travel through
solids and liquids. They travel through liquids more slowly.• S-waves (secondary) are transverse and cannot travel through
liquids.
Elements Found in each Layer of Earth
• Core: Fe, Ni
• Mantle: O (44%), Mg (22%), Si (21%), Fe (6%)
• Crust: O (46%), Si (28%), Al (8%), Fe (5%)
• DENSITY TREND EXISTS FOR THE ELEMENTS
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