Basic structure of the earth
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Basic Structure of the Earth. Definitions. Pressure – amount of force acting on a surface Plastic - Capable of undergoing continuous deformation without rupture or relaxation Convection – Transfer of heat (energy) through the movement of mass Density – mass per unit volume, g/cm 3

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Basic Structure of the Earth

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Basic structure of the earth

Basic Structure of the Earth


Definitions

Definitions

  • Pressure – amount of force acting on a surface

  • Plastic - Capable of undergoing continuous deformation without rupture or relaxation

  • Convection – Transfer of heat (energy) through the movement of mass

  • Density – mass per unit volume, g/cm3

  • Seismic – having to do with earthquakes


Shape of the earth

Shape of the earth


Shape of the earth1

Shape of the Earth


Slice of the earth

Slice of the Earth


More detailed view

More Detailed View


Compositional vs mechanical

Compositional vs. Mechanical


Compositional

Compositional

Mechanical


Temperatures

Temperatures


Convection in the earth s mantle

Convection in the Earth’s Mantle


Earth s layered structure

Layers Defined by Composition

Earth’s Layered Structure

 Earth’s interior consists of three major zones defined by their chemical composition—the crust, mantle, and core.

 Crust

• Thin, rocky outer layer

• Varies in thickness

- Roughly 7 km in oceanic regions

- Continental crust averages 8–40 km

- Exceeds 70 km in mountainous regions


Earth s layered structure1

Layers Defined by Composition

Earth’s Layered Structure

 Crust

• Continental crust

- Upper crust composed of granitic rocks

- Lower crust is more akin to basalt

- Average density is about 2.7 g/cm3

- Up to 4 billion years old


Earth s layered structure2

Layers Defined by Composition

Earth’s Layered Structure

 Crust

• Oceanic crust

- Basaltic composition

- Density about 3.0 g/cm3

- Younger (180 million years or less) than the continental crust


Earth s layered structure3

Layers Defined by Composition

Earth’s Layered Structure

 Mantle

• Below crust to a depth of 2900 kilometers

• Composition of the uppermost mantle is the igneous rock peridotite (changes at greater depths).


Earth s layered structure4

Layers Defined by Composition

Earth’s Layered Structure

 Core

• Below mantle

• Sphere with a radius of 3486 kilometers

• Composed of an iron-nickel alloy

• Average density of nearly 11 g/cm3


Earth s layered structure5

Layers Defined by Physical Properties

Earth’s Layered Structure

 Lithosphere

• Crust and uppermost mantle (about 100 km thick)

• Cool, rigid, solid

 Asthenosphere

• Beneath the lithosphere

• Upper mantle

• To a depth of about 660 kilometers

• Soft, weak layer that is easily deformed


Earth s layered structure6

Layers Defined by Physical Properties

Earth’s Layered Structure

 Mesosphere (lower Mantle)

• 660–2900 km

• More rigid layer

• Rocks are very hot and capable of gradual flow.


Earth s layered structure7

Layers Defined by Physical Properties

Earth’s Layered Structure

 Inner Core

• Sphere with a radius of 1216 km

• Behaves like a solid

 Outer Core

• Liquid layer

• 2270 km thick

• Convective flow of metallic iron within generates Earth’s magnetic field


Earth s layered structure8

Earth’s Layered Structure


Earth s layered structure9

Discovering Earth’s Composition

Earth’s Layered Structure

 Crust

• Early seismic data and drilling technology indicate that the continental crust is mostly made of lighter, granitic rocks.

 Mantle

• Composition is more speculative.

• Some of the lava that reaches Earth’s surface comes from asthenosphere within.

 Core

• Earth’s core is thought to be mainly dense iron and nickel, similar to metallic meteorites. The surrounding mantle is believed to be composed of rocks similar to stony meteorites.


Facts

Facts

  • We only know about the core through studying seismic (earthquake) waves and volcanic rocks

  • Deepest well ever drilled was only 12 km deep

  • The crust is only 1% of earth’s mass

  • The mantle is about 65% of earth’s mass

  • The core is about 34% of earth’s mass

  • Pressure at the center of the earth is about 3.3 million atmospheres

  • The temperature in the center of the earth is roughly the same as the surface of the sun


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