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Flashcards in Chapter 8.3 Deck (13)
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1

Plate Tectonics

The theory concerning the movement of the continental plates

2

Convection Curent

Circular movement that occurs when warmer, less dense fluid particles rise and cooler, denser fluid particles sink

3

Continental Crust

the plates of the Earth's crust that make up the land. 30-70km thick

4

Oceanic crust

one of the types of crust that makes up the Earth's outer layer. Oceanic crust is thinner than continental crust and made up of dense, heavy rocks such as basalt. On average they are 6km thick

5

Boundaries

The edges of tectonic plates.

6

Subduction

process in which two tectonic plates push against each other, and oceanic crust sinks below the less dense continental crust.

7

Destructive Plate Boundaries

A convergent boundary where two plates collide.

8

Constructive Plate Boundary

plate that creates new land from cooling magma.

9

Laurasia

One of the two smaller continents created when the supercontinent Pangaea broke apart about 200 million years ago.

10

Gondwanaland

one of the two smaller continents created when the supercontinent Pangaea broke apart about 200 million years ago.

11

Hotspots

A localised place where an activity occurs.

12

Why do the plates move?

The plates move because heat causes the partially molten rock in the mantle to expand and rise towards the surface. It spreads out, cools and falls back under the force of gravity. This creates a convection current that keeps the plates moving slowly.

13

How is new oceanic crust made?

As the plates move apart, magma from the mantle rises. As it cools and solidifies in the sea water, it forms underwater volcanoes and creates new oceanic crust