✅3.1.5.2 - Plate Tectonics Flashcards

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1
Q

Describe the crust:

A

The thin layer of the outer shell that we live on, 5-10km thick beneath oceans and 70km thick beneath continents, lithosphere

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2
Q

Describe oceanic plates:

A

An occasionally broken layer of basaltic rocks known as sima - silicon and magnesium

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3
Q

Describe continental plates:

A

Bodies of mainly granite rocks, known as sial - silicon and aluminium

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4
Q

What is the lithosphere?

A

The crust and upper mantle, where tectonic plates are formed

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5
Q

How thick is the mantle?

A

2900km

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6
Q

What is the asthenosphere?

A

A layer of soft, plastic like rock that carries the lithosphere

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7
Q

How hot is the core?

A

5000 degrees C

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8
Q

What are intrusive rocks?

A

Rocks formed by the cooling of molten Magma, that crystallises and solidifies slowly below the surface. Forms coarse grained igneous rocks. Vertical dykes and inclined sills may form within.

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9
Q

What are extrusive rocks?

A

Lava that is in contact with the air or sea. It cools, crystallises and solidifies much quicker than Magma that is still underground. Fine grained rocks with small crystals.

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10
Q

What is gravitational sliding?

A

The movement of tectonic plates under the influence of gravity

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11
Q

What is ridge push?

A

Gravity acting on the weight of the lithosphere near the ridge pushes the older part of the plate in front.

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12
Q

What is slab pull?

A

The lithosphere sinks into the mantle under its own weight following subduction, helping to ‘pull’ the rest of the plate with it.

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13
Q

What events and landforms occur at Constructive boundaries?

A

Volcanoes
Mid ocean ridges
Rift valleys

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14
Q

What events and landforms occur at Destructive boundaries?

A

Powerful earthquakes
Volcanoes
Fold Mountains
Ocean trenches

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15
Q

What events and landforms occur at Collision boundaries?

A

Powerful earthquakes

Fold Mountains

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16
Q

What events and landforms occur at Conservative boundaries?

A

Powerful earthquakes

17
Q

What is jigsaw fit evidence for tectonic theory?

A

Similarity in outlines of West Africa and South America as well as other continental areas. Best fit at 1000m below sea level.

18
Q

What is geological fit evidence for tectonic theory?

A

Ancient rock outcrops from South America and West Africa from over 2000 million years ago were continuous

19
Q

What is Tectonic fit evidence for tectonic theory?

A

Fragments of the Caledonian mountain belt are found in Scotland, England, Greenland, Canada and Scandinavia

20
Q

What is glacial deposit evidence for tectonic theory?

A

300 million year old deposits found in Africa, Australia, Antarctica, South America and India suggest ancient ice sheet

21
Q

What is fossil evidence for tectonic theory?

A

Bands of identical fossils lie across continents, particularly of organisms which could not have travelled.

22
Q

What happens at a conservative boundary?

A

Two plates do not directly collide but slide past one another

23
Q

What happens at a constructive boundary?

A

2 plates are moving apart, leaving a gap for magma to rise up through. Volcanoes form but don’t erupt with force and earthquakes occur

24
Q

Where are rift valleys common?

A

Where 3 plates meet at a junction

25
Q

What happens at destructive boundaries?

A

Dense oceanic plate descends beneath less dense continental plate. Oceanic plate melted due to friction forming magma

26
Q

What happens at collision boundaries?

A

Two plates of similar densities move together, causing the material between them to buckle and rise up

27
Q

Where do rift valleys form?

A

On constructive boundaries

28
Q

How do rift valleys form?

A

Magma rises and plates move apart
Over a magma chamber, crack and faults appear
Blocks of crust descend into mantle, creating steep sided valleys
Central plateaus sink in the middle, forming lakes

29
Q

What is a Benioff zone?

A

The further the rock descends, the hotter it gets. Together with the heat from friction begins to melt the plate to magma

30
Q

What boundaries do ocean trenches form at?

A

Destructive