3.1 Elementary plate tectonics Flashcards Preview

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Flashcards in 3.1 Elementary plate tectonics Deck (21)
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1

Benioff zone

Narrow zone of deep earthquake foci at a subduction zone.

2

Continental crust

Part of the Earth's crust that forms the continents.

3

Continental drift

Theory that the continents have drifted across the surface of the globe.

4

Convergent plate boundaries

Margins where plates are moving towards each other.

5

Core

Central part of the Earth below 2900 km from the surface.

6

Crust

Outermost layer of the Earth. It may be divided into continental and oceanic.

7

Divergent plate boundaries

Plate boundaries in which the plates are moving apart.

8

Hotspot

Relatively small area where magma rises through a continental or ocean plate. As the plate moves across a hot spot a chain of volcanoes may be formed

9

Island arcs

Chains of volcanic islands on the continental side of an ocean trench. Associated with a subduction zone.

10

Lava

Molten magma that reached the Earth's surface

11

Lithosphere

Outermost layer of the Earth, comprising the crust and part of the mantle.

12

Magma

Molten rock within the Earth. When it reaches the surface it is called lava.

13

Mercalli Scale

Scale of earthquake intensity based of descriptive data.

14

Mid-ocean ridges

Lines of mainly mountains formed when two ocean plates are separating

15

Oceanic crust

Part of the crust underlying the oceans.

16

Oceanic trenches

Arc-shaped depressions formed at subduction zones where one tectonic plate plunges a less dense continental one.

17

Oceanic ridges

Largest feature of the ocean floor. They are essentially a linear belt of submarine mountains.

18

Ritcher scale

Open ended scale to record the magnitude of earthquakes.

19

Sea-floor spreading

Where ocean floors grow as plates move apart at constructive margins.

20

Shield

Continental area that has not been deformed since Pre-Cambrian times.

21

Subduction zone

Area where one plate sides beneath another, where earthquakes occur.