continental drift Flashcards
(23 cards)
what is continental drift
the idea that continents moved horizontally to their current locations
the theory of continental drift was developed by who?
Alfred Wegener
what is pangea ?
the connection of all continents as one large landmass
what are some evidence of continental drift?
1) continents fit togetger like a jigsaw puzzle
2) fossils have been found in south africs and africa
3) glacial deposits and grooved bedrock found in southern parts of south america, africa india and australia
4) parts of Appalachian mountains in easter Us similar to those in Greenland and Weatern Europe
What are Tetonic Plates
ridgid segments of the earths crust
What is the Thwory of Plate Tetonics
the idea that the earthe crust and upper mantle are broken into sections that mkve around on the mantle
what are the two types of plates
oceanic and continental
describe oceanic plate
thin layer of rock under the oceans which are made up of denser material called silica magnesium (SIMA)
describe continetnal plates
thick and made up of old continetal material called silica aluminum (sial)
how many plate boundaries are there
three
what are the three plate boundaries
divergent boundaries
convergent boundaries
transform boundaries
what are thw three ways in which tetonic plates movd
divergent movement
convergent movement
transform movement
give a description of convergent plate movement
1) plates move towards each other
2) boundary known as destructive plate boundary
how many types of convergent boundaries are there
3 !
what are the three types of CONVERGENT boundaries
1) ocean floor plate collides with less dense continental plate
2) ocean floor plate collides with another ocean floor plate
3) continental plate collides with another continental plate
what are divergent boundaries
boundaries between 2 plates that are moving AWAY from each other
what happens durinf divergent playe MOVEMENT
1) plates move AWAY from each other which causes gap/rift
2) magma rises to fill gap
3) magma cools/hardens to form new crust (sea floor spreading)
what is sea floor spreading
process by which new crust is formed at divergent plate boundaries
what are three types of convergent margins
oceanic to continental
oceanic to oceanic
continental to continental
describe transform plate boundary
1) plates slide past each other
2) also known as neutral/conservative
3) causes earthquakes bc friction is created when plates move past each other
describe oceanic to continental convergence
- denser oceanic plate dips under the lighter continental plate
- that ^ area is called subduction zone and forms an ocean trench
- oceanic plate enters mantle and melts to magma
- magma rises through breaks in the continental plate to form volcanoes
describe oceanic - oceanic convergence
the denser oceanic plate will subside snd melt in the mantle. magma will rise through breaks in other oceanic plate to form submarine volcanoes.
overtime submarine volcanoes will emerge from the sea become islands
describe continental to continetal convergence
plates are of similar density and remain buoyant. No subduction as neither can sink beneath the other
both plates are compressed and pushed upwards to form fold mountains
