plate tectonics Flashcards
Continental drift
The movement of the earths continents relative to each other
when did Alfred Wegener develop his hypothesis
1912
evidence of continental drift and plate tectonics
The continental puzzle fossils climate geology and sea floor spreading paleomagnetism
Continental puzzle
The coastlines of complementary continents match shapes
fossil
fossils of the same species are found on matching continents
climate
evidence left behind by a shake glaciers indicate areas of common climates
geological
matching rock types and mountain ranges on adjoining continents
paleomagnetism
The earths magnetic pole shipped every few thousand years and magnetic minerals aligned themselves with the polls and it was discovered after Wegener’s time
sea floor spreading
discovered in 1960 by Harry has and gave credibility to Wegner’s hypothesis and reopen the discussion in scientific circles
seven major plates
earths surface consists of a number of rigid but moving pieces
theory of plate tectonics
earths outer layer is made up of multiple plates that change position
lithosphere
The solid portion of the earth broken into plates that mood with respect to one another and it’s made of crust and upper mantle and floats on the atmosphere
oceanic crust
made up of a material on the ocean floor
Continental crust
made up of the continental landmasses
asthenosphere
later with the mantle that the lithospheric plates rest on
mechanisms for plate tectonics
convection currents, gravity, earths rotation
main reason Wagner was dismissed
he had no propose mechanism of movement
convection current
convection is the transfer of heat, hotter material rises displacing cooler material, currents with an Earth’s mantle are created due to convection
Gravity
slab pull occurs as the subducting plate sinks below the hot mantle beneath it and cooler material is more dense
Coriolis effect
affects water movement
plate boundaries
place where one plate is moving relative to another plate and boundaries are also areas of high heat flow, magma moves upward to surface and forms a volcano
divergent boundaries
places where to lithospheric plates are moving apart and contain mid ocean ridges with deep valleys called rift valleys
seafloor spreading
occurs when divergent occurs between two oceanic plates and hot magma rises, cools, and builds up the sea floor
mid ocean ridge
underwater mountain range formed by plate tectonics
ridge push
The newly cool and material spreads out, pushing the plates further apart
ridge push
gravitational force that causes a plate to move away from the crest of an ocean ridge and into a subduction zone
rift Valley
The valley between mid ocean ridges
converging boundaries
places were to oceanic plates come together
oceanic to oceanic crust convergence
One plate is subducted, forms trench, subducted play melts, molten rock rises to surface a long trench, forms island chain called an island arc
Continental to oceanic convergence
when an ocean play and continental plate collide, ocean plate slides under continental plate
Continental to continental convergence
two continental plates collide, become crumpled and uplifted, for mountain ranges, continental crust resist subduction
transform fault boundary’s
lithospheric plates are sliding past one another and example is the San Andreas Fault
mountains
natural elevations of earths surface that are created through tectonics
orogenesis
processes that result in the formation of mountains
when rocks undergo stress
they can deform
how do rocks deform
it depends on the rocks strength
what influences rock Deformation
Rock type, pressure, temperature, time
Deformation
changes in the original shape/size of a rock body
brittle deformation
Low temperature and low-pressure
fracture once rock strength has exceeded
pencil snaps
ductile Deformation
high temperature and high pressure, mold rocks, not break them, Clay bends
mountains are classified by
The processes that formed them
folded mountains are the
most common type and occurred under high temperatures and high pressures
“compressional stresses”
mountains can be formed when the crust
“folds”
types of mountains
folded mountains
fault block mountains
volcanic mountains
fault
Break or crack along which rocks move, it is caused by stress
faulted rocks have 2 blocks
hanging wall
Block of rock above the fault
footwall
Block of rock below fault
normal fault
formed when hanging wall moves down relative to the foot wall
reverse fault
formed when hanging wall moves up relative to the footwall
strike-slip fault
rocks on either side of fault are moving past each other
