Chapter 12.1 continental drift theory Flashcards
What is the Continental Drift Theory?
The theory that continents have not always been in the same locations but have been drifting over millions of years
What evidence contributes to the Continental Drift Theory?
Jigsaw puzzle fit (Pangaea)
Mountain Ranges/Age old rocks
Matching Fossils
Paleoglaciation
Explain the Jigsaw puzzle fit
Continents appear to be like a puzzle, for example, africa and south
explain mountain ranges
mountains start on continent, end at coastline, start again on other continent
major mountain ranges would have been connected
explain rocks
rocks have the same structures/folds on different parts of the world
rocks that are similar in age are in different parts of the world
ex rocks in newfoundland are the same age/type as rocks in norway, greenland, scotland and ireland
explain matching fossils
past species or fossils have been found in different parts of the world often separated by thousands of km of ocean
mesosaurus is one of them, a small animal could not have possibly swam across 6000 km of ocean between southeastern south america and southwest africa
explain paleoglaciation
paleoglaciation is the extent of ancient glaciers and the rock markings they have left behind
evidence of glaciers (marks from glaciers advancing and retreating) in tropical parts of the world puzzled scientists
ex. india and africa
How do the continents move?
tectonic plates shifting on hot semi liquid mantle (like rafts floating on water)
wat are tectonic plates?
large, moveable slabs of rock floating and sliding over a layer of partly molten rock
what are volcanoes?
openings in earth’s surface that spew out lava, chunks of rock and gas
wat are earthquaku?
a sudden ground shaking in the earth from the release of pent of energy
wat is earth’s magnetic field?
earth is like a giant magnet, with north and south magnetic poles and a magnetic field from the flow of liquid iron and other materials in the core creating electric currents
wat is magnetic reversal?
when the north and south magnetic poles reverse completely thousands of years
if the motion of liquid iron in the core changes in some way, the poles switch
what is paleomagnetism?
the study of magnetic properties in ancient rocks
what is magnetic striping?
a pattern of stripes in iron containing materials in the ocean floor
pattern depends on normal magnetic polarity or reverse magnetic polarity
