A summary of diagrams and key facts about the ccea plate tectonics including case studies(Pinatubo and tohoku) it also includes some past paper questions at the bottom of the summary.
The Structure of the Earth
mummmann
crust oceanic continenta
mono
uppermantle
mantle
outer core
y
lithosphere
g inner core
Asthenosphere
crust thin outer layer made of rocks of
continents Ocean floor 5km 60km thick Can be
ceanic or continental
thickness Rockdensity Rocktype Rock age
it
91 thins 7km dense Basalt younger
6250million
Effstental thick1060km less dense Granite Older
1000 35000million
Moho where the rocks of the crust meet the mantle
Mantle outer mantle solid rock Inner mantle
liquid They're mad
up of magma convection currents occur here
Lithosphere part of upper mantle thin crust
Athenosphere liquid lowermantle
, outer core liquid core Whole core 7000km
Inner core solid core made of iron creates
planets magnetic fiel
convectioncurrentsm
me exchange of energy in the form of heat by flows of
quid
ircular movements
s magma is heated it rises as it cools it sinks
Makes plates more
core
Plate tectonic theory w
mammmmm
continental drift A theory by Alfred Wegener The
worlds continents have changed their location over
geological time
Evidence
Jarrellet coastlines southAmerica western Africa match up Pangea all the
ontinental Shelves match up
nearly perfectly tropic of cancer
Climatic evidence Ireland tok used to be in the
isn't likely to form here as it
coal is found in antartica coal
needs tropical climates t dense vegetation to form continent Fossil
found across the southern
Fossil evidence seedFern fossils in Africa and South America
reptile found
emains ofsmallFreshwater
unlikely they swam
, of volcanos earthquakes seisometer measure them
Distribution
both Volcanic t seismic activity tends to occur in longnarrow linear
anas sometimes along the coastlines or through the oceans
eg the
ing of fire in pacific ocean
Topography
of oceans the first ocean basin maps were created
i a sonar techniques It shows that
the ocean floor has huge
near mountain ridges with deep central
the centre valleys running down
They Strech in a continuous line around the
Arth Eg North Atlantic Ocean Basin
Age t pattern of the Ocean Basin Geology much less
material on ocean floor than expected ocean
were as old as continents If floors
deposited sediment but there
they should have lots of
was no sedimentscientists
ound ocean floors were
young Iceland shows rock age
atterns commonly found in the ocean
onstructive margins floor around
Paleomagnetism
magnetic stripping When molten rock
olidifies iron particles in the rock line up with earths
agnetic field This field reverses every250000years scientists
an work out where rocks originally were In Antarctica
there are
anded symmetrical patterns on the ocean
floor
, V Harry sea floor Hess spreading n
W mm mm u
developed theory in 1960s
mid ocean ridges are weak zones in the crust
lean floor is being pulled where the
apart along the ridge crest new
magma from deep mantle rises
ones t erupts along the crest easily through the weake
rust of ridges creating new oceanic
Evidence
exsistance of Submarine mountain chains
2 At mid ocean ridges rocks are very
youngthey get older
furthe
away
Bands of rock parrellel to ridge have alternating
polarity
magnetic
He further said if earths
crust was growing but
xpanding thencrust mustbe shrinking earth isn't
Thetheory explains
why
the earth doesn't
get bigger despite sea floor spreading
there is little accumulation
of sediment on the ocean
floor
the rocks forming the
much younger than floor of the ocean basins are
continental rocks
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