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what year did wegener publish his theory?
1912
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what was the continent called? when did it exist?
called pangea, existed 300 million years ago
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it split into
laurasia [north]. gondwanaland [south]
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stage 1
permian
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stage 2
triassic
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stage 3
jurassic
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stage 4
cretaceous
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stage 5
present day
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four stages of evidence which supported his theory
continental fit, geological, climatological and biological
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continental fit
western seaboard of africa and eastern seaboard of south-america
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geological evidence
glacial deposits in south america, antarctica and india
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geological evidence 2
striations of the same orientation in brazil and west africa
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climatological evidence
coal deposits in north america, uk and svalbarn
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when have they drifted since?
drifted since the carboniferous period
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biological evidence
mesosaurus fossil formation in south america and south africa
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when were the sediments from?
the permian fossil age
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when did evidence start to gather to prove wegener's theory?
from 1940s onwards
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when did they survey the floor of the atlantic ocean?
1948
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what did this reveal?
a continuous ridge running largely north to south
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how wide?
1000km wide
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what height?
2-5km high
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what was it composed of?
volcanic rock
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when did they conduct a magnetic survey?
1950s
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what did this show?
regular patterns of paleomagnetic striping about the ridges
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how often does the earths polarity reverse?
every 400,000 years
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what was further evidence for sea-floor spreading?
establishing the age of the ocean floor
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what did this show?
young ages near the ridges [iceland] and much older ages near continental masses
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what did they then discover?
ocean trenches which provided the mechanism for sea floor spreading
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example of a slow-spreading ridge
mid-atlantic ridge
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what do they look like?
large, wide rift valleys
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how many km?
10-20km rift valleys
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what terrain?
rugged terrain at the ridge crest that can have a relief of up to 1,000m
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example of a fast spreading ridge
east pacific rise
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what does it look like?
narrow, sharp incisions surrounded by generally flat topography
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what is a mid-ocean ridge?
an underwater mountain system conisting of various mountain ranges typically having a valley running along its spine
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how long is the continuous mountain range?
65,000km long
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when was island of surtsey formed?
november 14th 1963
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what are ophiolites?
fragments of the ocean floor are left at the surface during subduction and layers of pillow basalyts and deep ocean sediments exposed
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example of ophiolite
Troodos Ophiolite Suite, Cyprus
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example of an eruption which covers a massive area of land and develops enormous thickness
the Deccan Traps of India and Siberian Traps
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what happened to the Red sea and Gulf of Aden
stretched zone of thinned crust consisting of a mix of basaltic and continetal rocks, drops below sea level
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example of rifting in a continental setting
east african/gregory rift
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why is rifting in east africa complicated?
two branches have developed
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which branch is to the west?
African Great Lakes [rift filled with water]
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which one is parallel to this?
another rift is 600km east which nearly bisects Kenya north-to-south before entering Tanzania
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which lake sits between these two branches?
lake victoria
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evidence of a hot spot under central Kenya
demonstrated by the elevated topographic dome
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how long is the great east african rift valley?
4000km long
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how many km wide?
50km wide
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what depth?
600 depth
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what has happened to the north?
two rifts widened into the Red Sea and Gulf of Arabia
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example of underwater rift valley
northern crest of the mid-atlantic ridge
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which plates are splitting apart?
north american plate and the eurasian plate
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how many cm a year?
2.5cm
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how many km wide?
15km wide
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what are underwater rift valleys usually dotted with?
hydrothermal vents which spew superheated water and toxic-vent fluids
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name the only two continental rift valleys
Baikal Rift Valley and the East African Rift
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which lake is in the Baikal rift valley?
Lake Baikal, the depest and oldest freshwater lake in the world
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which plates are moving to form the Baikal rift?
amur plate is tearing away from the Eurasian plate
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how long has it being doing this for?
25 million years
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what is the deepest part?
1,187m
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where does the "great rift valley" extend from
middle east in the north to madagascar in the south
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what has happened in modern day?
each rift in the area are connected but not part of a single system
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jordan rift valley
between jordan and israel and includes the dead sea at 377m
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what is south of the jordan rift valley?
red sea rift
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what happened?
arabian and african plates rifted apart and the indian ocean flooded the rift valley
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what did this create?
the red sea
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what is south of the red sea?
east african rift
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example of smaller rift
Afar Triple Junction sits at the meeting of the 3 tectonic plates on the Horn of Africa
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examples of fold mountains
himalayas, andes and the alps
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where do they form?
destructive margins
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what are depressions in the sea floor caled?
geosynclines
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what are rocks called that are folded upwards?
anticlines
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what are severly folded rocks called?
nappes
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example of an island arc
west indies
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example of continental land mass
volcanoes on the Andes
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which plates form the Andes?
Nazca subducts the south american plate
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example of continental/continental
Himalayas as the indian plate is moving north towards stationary european plate
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example of island arc
japanese islands, Aleutian islands
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example of oceanic/continental subduction
peru-chile trench, off the west coast of south america
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what is this form from?
formed by the Nazca plate [oceanic] subducting benetah the South American plate
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where is the Mariana trench located?
western pacific east of the Phillipines and around 200km from the Mariana islands
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what is it?
crescent shaped scar in the earths crust
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how long and wide?
1,500miles long and 43 miles wide
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how far below the earths surface is challanger deep
10,994m below
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interesting fact
mt everest could fit in with more than 1 mile to spare
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Card 2

Front

what was the continent called? when did it exist?

Back

called pangea, existed 300 million years ago

Card 3

Front

it split into

Back

Preview of the front of card 3

Card 4

Front

stage 1

Back

Preview of the front of card 4

Card 5

Front

stage 2

Back

Preview of the front of card 5
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