The Earth's History Flashcards

1
Q

How is Earth Structured?

A

Earth has a differentiated crust, meaning that different layers have different properties. This is the main feature that makes our planet dynamic. This allows the Earth to evolve with mountains, oceans, volcanoes.

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2
Q

What is Differentiation with Planets?

A

When planets formed by accretion, they start off homogenous. The earth and other terrestrial planets do not remain this way - they become differentiation or internally layered.

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3
Q

How does Differentiation Occur?

A

To be accomplished, the earth must be heated and partially melted. When this happens, heavy metals (like iron and nickel) would move downward to form a dense core. Less dense material would form around the core. Lighter material would separate out around this later, forming the uppermost crust.

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4
Q

Does the planet need to be completely melted or can it just be partially melted?

A

It just needs to be partially melted.

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5
Q

Where does heat come from to accomplish the melting of planets?

A

Some of the heat to accomplish melting comes from impacts during earths accretion, some comes from Radioactive Decay, and some is produced by gravitational compression.

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6
Q

What is Radioactive Decay?

A

Some isotopes are not stable, they decay over time to stable isotopes. The time it takes half of the material to decay is called the half-life. When an isotope decays, it produces a particle (radiation and energy). This energy is the source of the heat. This continues to occur until a stable atom is left.

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7
Q

How is heat produced by gravitation compression?

A

As the earth becomes larger, the pull of its gravity increases. This reduced the size of the Earth and adds heat.

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8
Q

Describe the Internal Structure of the Earth.

A

The core is made up primarily of nickel and iron. Divided into a solid inner core and liquid outer core. The mantle is rocky and divided into different layers.

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9
Q

What is the Earth’s Lithosphere?

A

The Earth’s crust and upper mantle.

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10
Q

What is the Earth’s Asthenosphere?

A

The asthenosphere is in the high mantle and has a slushy mixture of solid and melted rock.

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11
Q

What is the division between the crust and mantle called?

A

The Mohorovicic Discontinuity (Moho).

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12
Q

What is the composition of the Continental crust?

A

Light and thick.

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13
Q

What is the composition of the Oceanic crust?

A

Thin and dense.

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