techtonics Flashcards
risk
a situation involving exposure to danger
What two things make a situation risky?
a dangerous event and exposure
Who discovered continental drift?
Alfred Wegener
Continental drift
the theory of the gradual movement of the continents across the earth’s surface through out time, starting as one land mass called Pangea
Alfred Wegener
a German meteorologist who discovered the theory of continental drift
How were continents at the beginning?
Permian period: Pangea- 225 million years ago
Evidence of Continental Drift
jigsaw
similar animal fossils and rock types found across continents
shells found on Himalayas
order of layers in the Earth
inner core / outer core / mantle / crust
crust
thin (20-80km), made of solid rock, mostly basalt and granite
mantle
a viscous semi-solid with convection currents circulating in
outer-core
liquid, mostly made of iron and nickel
inner- core
dense and extremely hot, made mostly of solid iron and nickel
convection currents
circulating currents that move the crust on top of the mantle and cause tectonic plates to move
plate boundary
where two tectonic plates meet
name all tectonic plates
Eurasian/North American/South American/Nazca/African/Indo Australian/Pacific
