Plate Tectonics- Basics Flashcards Preview

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Flashcards in Plate Tectonics- Basics Deck (27)
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0
Q

The inner core contains…

A

Nickel and iron

1
Q

Name the earths structure from inner core to crust, and name whether each layer is solid, semi-molten, molten or rigid.

A
Inner core (solid)
Outer core (semi-molten)
Mantle (molten)
Asthenosphere (semi-molten)
Lithosphere (rigid mantle and crust)
2
Q

The outer core contains…

A

Iron and nickel

3
Q

Two types of crust…

A

Continental

Oceanic

4
Q

Oceanic crust is… (thickness, density)

A

Thinner, 6-10km thick, but more dense

5
Q

Continental crust is… (thickness, density)

A

Thicker, 30-70km, less dense

6
Q

What is the lithosphere?

A

Rigid upper mantle between asthenosphere and crust.

7
Q

What is the asthenosphere?

A

Semi-molten section of mantle.

8
Q

Mantle contains…

A

Silicate rocks

9
Q

The lithosphere is divided up into lots of sections called…

A

Tectonic plates

10
Q

The plates move due to _ _ _ _ _ _ _ _ _ _ within the _ _ _ _ _ _ _ _ _ _ _ _ _

A

Convection currents

Asthenosphere

11
Q

The place where two plates meet is called a…

A

Plate boundary or margin

12
Q

Who came up with the Theory of Plate Tectonics?

A

Alfred Wegener

13
Q

Alfred Wegener thought that…

A

The continents had drifted apart over millions of years from a Supercontinent called Pangaea.

14
Q

What evidence did Wegener provide to support his theory?

A

The shapes of the East coast of South America and the West coast of Africa fit together.
Fossils, plant and rock types found on those coastlines suggesting they were once joined.

15
Q

Why was Wegener’s theory disregarded by the geoscientific community?

A

He could not provide an explanation as to why the continents were drifting apart.

We obviously now know good old Alfred was barking up the right tree, and that convection within the mantle causes continental drift.

16
Q

Where is new crust created?

A

When plates move apart- divergent or constructive boundaries

17
Q

What is the name for when divergent (constructive) margins occur below water?

A

Sea-floor spreading

18
Q

When did Alfred Wegener propose his theory?

A

1912

19
Q

What did Bruce Heezen and Marie Tharp discover?

A

The mid-Atlantic ridge

20
Q

Palaeomagnetism involves…

A

Mapping the magnetic fields of the earths surface.

21
Q

How often do the earths poles switch/ reverse?

A

Every 200,000 years or so, the earth’s magnetic field reverses polarity (N and S switch)

22
Q

What does Palaeomagnetism provide evidence for?

A

Sea floor spreading.

23
Q

Example of constructive plate margin in the ocean…

A

Mid-Atlantic ridge

24
Q

Difference between mid-ocean ridge and Rift Valley…

A

Mid-ocean ridge: plates diverge underwater

Rift Valley: plates diverge beneath land

25
Q

Example of rift system…

A

East African Rift System (stretching from Mozambique to the Red Sea)

26
Q

What occurs at constructive, destructive and conservative plate margins: earthquakes, volcanoes, or both?

A

Constructive: both
Destructive: both
Conservative: only earthquakes