Plate Tectonic Theory Flashcards
plate techtonics is what
- a theory describing the origin, movement and recycling of lithospheric & continental plates
- unifying theory of geosciences
plate techtonic theory was formalized in
1967
what does plate techtonic combine
combines continental drift and seafloor spreading
who was the continental drift guy and when was the first proposal
alfred lothar wegener
1912 was the first formal proposal of continental movement
how do the mountain support continental drift theory
there were mountains that contained the same rocks/size that were separated but they were clear that they were once together..
how do fossils (plant) support continental drift theory
glossopteris (seed fern with tounge shaped leaves were found in south america, africa, india, antartica, aurtralia and new zealand.
the overall question is how they got to continent to continent, they were too big to be picked up by wind. 200-300 MA
how do fossils (reptile) support continental drift theory
Mesosaurus
freshwater atlatic reptile
found in south america and southern africa (across the pacific ocean from eachother) since it is a freshwater reptile, it can not possibly get across the ocean ~300 MA
how do fossils support continental drift theory (herbivore)
lystrosaurus
found in africa, australia, india, china, mongolia, and russia. cannot get across the ocean again because it is a land animal ~250 MA
how do fossils support continental drift theory (Mammal)
cynognathus
~350 MA
south americ and africa
cannot get across the ocean
how do glacial tillites support continental drift theory
the mapped out straitens are confusing in current locations
tillites def
glacial sediment deposits
striations def
scratches in rock, used to determine glacier movement
what is Pangaea
supercontinent (AKA all lands, all earth, whole land)
200-330 MA
what are 4 disagreements with the continental drift theory
- lots of evidence in south america, but a lack of evidence in North America
- NA geologists reject Wegener’s ideas
- called it a “poor mechanism” = rejection
- wegener dies of a heart attack, therefore the theory forgotten
what is SONAR
Sound navigation and ranging
when did SONAR start
WWI, however its use was continued throughout WWII to detect submarines and its use expanded after.
what is bathymetry
measurement of the oceans depths and the charting of seafloor
who is behind the seafloor spreading hypothesis
harry hess in 1962
what are some key takeaways from the seafloor spreading hypothesis
- new crust forms at the mid oceanic ridge
- crust is recycled at oceanic trenches
what is the driver of the seaafloor spreading hypothesis
mantle convection (warm mantle rises, cooler mantle sinks)
additional factors to seafloor spreading hypothesis
- ridge push
- slab pull (90)
- mantle drag
- slab roll back
- trench suction
layers by physical state
- lithosphere
- asthenosphere
- lower mantle
- outer core
- inner core
what is paleomagmetis, of seafloor (support of seafloor spreading theory)
- iron particles are mobile in magma
- align with the current fields
- locked in after cooling
what is the terrestrial palemagnetic record in support of seafloor spreading theory
- created from lava flows,
- there are normal and reversed intervals
what is the marine paleomagnetic record in support of seafloor spreading theory
- correlates to terrestrial record
- symmetrical patterns acroos the mid oceanic ridge
- predictive tool
how does creating marine magnetic record support the seafloor spreading theory
-
where do rocks become older
rocks become older with distance from the mid oceanic ridge
when do sediments become thicker
with distance from the mid oceanic ridge
how many major lithospheric plates
14
what does plate techtonic theory explain
explains distribution of landforms, biosphere, natural disasters,
- explains long term climate change
