Earth’s Interior Structure

Earth’s Origins 4.6 billion years ago Earth was a planetesimal developing into a planetoid. The only gasses present were Hydrogen and Helium No magnetic field Meteorite bombardment continued for over 500 million years aided Earth’s growth.

Earth’s Origins Meteorites contained rock-forming elements (Mg, Si, Fe, Al, Ca, Na, Ni) non-condensable elements (H, He, O, C, Ne, N, S, Ar, P).

Earth’s Origins Meteorite impact with Earth, some non-condensable elements evaporated on impact. Others have volatilized over time outgassed through, fumaroles, steam wells geysers. Volatilized = evaporated

Earth’s Origins Formation of the Earth’s Crust 4.5-4 bya, Earth’s core hotter. mechanism of energy escape - conduction conduction is slow Internal energy could not Dissipate entire Earth became molten surface was magma ocean. Volatilized = evaporated

Earth’s Origins Formation of the Earth’s Crust Convection all0wed more Energy to be released. This permitted Cooling of the surface Forming Earth’s crust 3.8 – 4.3 bya Volatilized = evaporated

Earth’s Interior Structure 1. Crust Thin outer layer B. Varies in thickness 1. 70 km in some mountainous regions 2. Less than in oceanic regions

Earth’s Interior Structure 2. Crust is made of two main parts A. Continental Crust Light granitic rocks granitic – Quartz Potassium Feldspar

Earth’s Interior Structure 2. Crust is made of two main parts B. Oceanic Crust- Heavier basaltic composition Plagioclase feldspar pyroxene

Earth’s Interior Structure 3. Lithosphere A. Crust and upper mantle (about 100 km thick) B. Cool, Rigid, Solid

Earth’s Interior Structure 4. Mohorovicic Discontinuity (The Moho) A. Separates the crust from the mantle 1. "discontinuity" is used for a surface at which seismic waves change velocity. B. exists at an average depth of 8 km beneath the ocean basin and 32 km beneath the continents. C. seismic waves accelerate

Earth’s Interior Structure 5. Mantle A. below crust B. 2885 km thick C. Composition similar to the rock peridotite

Earth’s Interior Structure 6. Asthenosphere A. Upper Mantle B. Depth of 100 to 350 Km C. Hot, weak rock D. Easily deformed E. Up to 10% is molten F. Key to the explanation of plate movement

Earth’s Interior Structure 7. Outer Core A. Below mantle B. 2270 km thick C. Mobile liquid D. Does not transmit S waves from Earthquakes E. Mainly iron and nickel composition F. Related to Earth’s magnetic field

Earth’s Interior Structure 8. Inner Core A. 1216 km Radius B. Solid C. Iron and Nickel composition D. High Density

Consequences of Core Formation Increase in gravity Increasing pressure in the center creating solid metallic inner core Release of pressure moving out from the center allows for a molten outer core Generates the magnetic field Less dense materials “floated” to the top (crust)

Earth’s Interior Structure

Physical Structure of the Earth (5 Layers) Lithosphere- rigid outer layer (crust) Asthenosphere- solid rock that flows slowly (like hot asphalt) Mesosphere- middle layer Outer Core- liquid layer Inner Core- solid, very dense

Earth’s Interior Structure

Quiz

1.The crust is ____ km thick in oceanic regions 70 5 75 57

2.Continental crust is made mostly of ________ rocks granitic basaltic granular crushed

3. The lithosphere includes the ______ and _______ Mantle and inner core Crust and lower mantle Mantle and atmosphere Crust and upper mantle

4. At the Mohorovicic Discontinuity, seismic waves ________ accelerate decelerate stop Reflect upwards

5.The mantle has a composition similar to ________ granite basalt peridotite quartz

6. The movement of the Earth’s plates is partly explained by the __________ Sauronsphere Atmosphere Lithosphere Asthenosphere

7.The outer core is a _______ Liquid Solid Gas Plasma

8. The inner core is composed of ______ and ______ Iron & Basalt Granite & Nickel Iron & Nickel Basalt & Granite

Earth’s Interior Structure