Continental Drift and Sea Floor Spreading Flashcards
What scientist hypothesized Pangea?
Alfred Wegner
What is Continental Drift?
The Hypothesis that that a single large landmass broke up into smaller land masses to form the continents, which then drifted to their present location.
What is Pangea?
A large landmass that consisted of all of the planets
What were the three Evidences Wegner had?
Evidence from land features- mountain ranges lining up on continents when pieced together.
Evidence from fossils- or traces of organisms perked in rock, show the same animals and plants occurred on the now separate land masses.
Evidence from climate change- Where Wegner showed scratches on rocks made from glaciers in places with much more mild climates today.
Why was Wegners idea rejected?
Because he couldn’t provide a satisfactory explanation for the push or pull of the continents
Who proposed a new idea to support Wegner theories?
Henry Hess
What was Henry Hess’s radical idea?
Sea Floor spreading.
What is sea floor spreading?
Sea floor spreads apart along both sides of a mid ocean ridge as new crust is added ocean floors move like a conveyor belt, carrying continents along with them.
What were Hess’s three evidences for sea floor spreading?
Evidence from Molten Material- which looked like pillow shaped rocks formed of molten material erupts and hardens quickly.
Evidence from magnetic strips- rocks that lie in a pattern showing record of reversals of Earth’s magnetic field.
Evidence from drilling samples- reveal that the farther from a ridge the rocks were taking the older they were.
What are deep ocean trenches?
Deep under water canyons.
What is subduction?
Where part of the ocean floor sinks back into the mantle over a long long time.
