Theory Flashcards
What was the name of the man, what did he propose and what year did he propose it?
Alfred wegener, Theory of Continental Drift, 1912
How many years ago were the continents joined and what was it called?
300 million, Pangea
What did the continent split into?
Laurasia (north), Gondwanaland (south)
Give an example of geological evidence
Africa and south america fit together
Give an example of biological evidence
Fossil remains of reptile ‘mesosaurus’ found in south america and southern africa, it could swim in salt water
What was discovered in which year which proved the theory was correct?
Mid-Atlantic Ridge, in 1940
What does the alternating polarity of rocks suggest?
Sea floor spreading
When lava solidifies what happens
iron particles align with the earths magnetic field and create a record of earths polarity at th time of the eruption
How often does the earths polarity reverse?
400,000 years
Whats suggests the oceans crust is spreading away?
Magnetic stripes which are mirrored exactly either side f the mid-oceanic ridge
Oceanic crust gets older with distance from what?
Mid-oceanic ridge
What does sea-floor spreading imply, and what is actually happening?
Implies earth must be getting bigger, but plates are being destroyed to accommodate increase in size
