Plate Movement Flashcards
Continental shelf
The part of the continental plate that stretches beyond the continent into the ocean
Tectonics
Relating to the plates and their involvement in the earths land masses
Crust
The thinnest layer of the earths structure. There are two types: continental and oceanic.
Big Bang
The theory States that about 13.7 billion years ago all the matter in the universe was concentrated into a single incredibly tiny point. This began to enlarge rapidly in an extremely hot explosion, and is still expanding to this day.
Mantle
Molten silicates and minerals from 2900km up, at temperatures up to 3800*c.
Core
From 2900km into the earth and down, is the size of Mars, densest part of the planet, made of rocks rich in iron and nickel
Mantle
Depth: 2900 km upwards
Mainly silicate rocks
Temperature: 3800C
Core
Depth: 2900km to centre Size: size of Mars Rich in iron and nickel Made up of semi-molten outer core and solid inner core Temperature: can reach 5000C
Lithosphere
The crust and upper mantle
Asthenospere
Rest of mantle
Primary Waves
The first waves of an earthquake
Secondary Waves
The second waves of an earthquake
Suface Waves
Seismic wave
Tectonic Plates
Irregularly shaped ‘raft’ of lithosphere ‘floating’ on the asthenosphere
Oceanic crust
Mainly Sima
Less than 200 million years old
Continental crust
Mainly Sial
Over 1500 million years old
Plate margins
Where two plates either: move apart, move towards each other or move past each other
Convection currents
Heat from core generates currents in mantle, which drive the movement of tectonic plates
Continental drift
Theory states that all continents were once together, and have all slowly drited apart from each other (and still are)
Alfred Wegener
A geologist who came up with the theory of continental drift
Jigsaw Fit
Continents that seem to fit together if places side by side
Evidence for continental drift
Pangaea
Ancient supercontinent
Glossopteris
Evidence for continental drift
Fossil found on two different continents (check)
Mesosaurus
Permian fossil reptile found only in south west Africa and Brazil
Sea-floor spreading
The sea floor is widening, evidenced by paleomagnetism
Suggested to be at 5 cm pa
Mid-Atlantic Ridge
Found at constructive plate margins, they are uplift features.
Formed when there is increased heat near the surface causing expanding of the crust, forming a ridge
Paleomagnetism
Every 400,000 years (approx) the polarity of the earths magnetic field swaps, and the rock being formed shows this (the iron particles align with the Earths magnetic field) forming magnetic ‘stripes’
Vine and Matthews
.
Harry Hess
Found evidence for sea floor spreading
Found that oldest (200 million) rocks in the Atlantic were nearest to the USA and Caribbean, newest (less than 1 mil) in the centre and being formed in Iceland
Constructive plate margin
Separating plates
Oceanic: either side of mid ocean ridges
Continental: creates rift valleys
Some of the earths youngest rocks (basaltic) can be found
Submarine volcanoes
Volcanoes formed under the sea at lower pressures
Can continue to erupt to form islands such as Iceland
Transform faults
Occur at right angles to the plate boundary as new crust forms and spreads
Can cause shallow focus earthquakes
Great African Rift Valley
Rift Valley on the east of Africa stretching for a total of 5500 km
Destructive plate margins
Where two plates move together, often creating a subduction
Subduction
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Benioff Zone
.
Ocean Trench
.
Fold mountains
.
Collision
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Island arcs
.
Conservative plate margin
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Fault line
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Hot spots
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Mantle plume
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Island chain
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Sea mount
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Supervolcano
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Caldera
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