chapter 8: plate tectonics Flashcards
vicariance
isolation of a population
ectotherm
relies primarily on its external environment to regulate the temperature of its body
- reptile/amphibian
Endotherms
able to regulate their body temperatures by producing heat within the body
- birds
geologic/deep time
all of earth’s history
index fossils (guide fossils)
wide-ranging species; lifestyles more independent of small-scale patches
- ex: freely dispersed marine habitats
eons (3)
~1 billion years
- Archaen
- Proterozoic
- Phanerozioc (all of life)
era (current era?)
2nd largest time scale
- current era = Cenozoic!!
period
2+ eras
cambrien period
increase oxygen = explosion life
carboniferous period
increase in plant life = increased in buried dead plants = created fossil fuels today
life is about ___ years old
3.7 billion
half-life
amount of time for 1/2 radioactive material to decay to stable element
- calculate ratio of radio/stable to date samples
earth is about how old?
4.55 billion
are rocks today as old as earth?
NO, younger!
radio carbon dating
age of organic materials by tracking decay (1/2 life) of carbon-14 (isotope)
ways of estimating times
radio active decay/radio carbon dating, tree-rings, glacial ice cores/growth lines, luminescence (time since burial = amnt of light)
continental drift theory
continents/portions of continents rafted across earth’s surface on viscous upper mantle (above crust; crust = fixed to oven basins)
earths crust is..
dynamic
plate tectonics theory
Earth’s lithosphere, is separated into plates that move over the asthenosphere
- plates come together, separate, and collide
- origin/destruction of plates and their drifts
lithosphere
earth’s solid outer crust/top layer of earth
- crust + upper mantle
plate subduction
one plate goes under the other, causes mountains or volcanoes
- main driver of plate tectonics today
before tectonics
core = too hot = holds continents together (1.8+ billion years ago); only had life in oceans until it cooled
tillites
glacial deposits in africa and South America where the poles once were
- wegener’s theory
sea floor spreading
plate’s move apart
- mid-oceanic ridges form and underwater mountain ranges can form
stratigraphic evidence for continental drift
formation of mountains, oceanic ridges, island chains, glaciers, coal beds, sand dunes
paleoclimatic evidence for continental drift
all continents in Southern hemisphere have tillites (@ S.)
paleontological evidence for continental drift
fossils and records
trenches
formed at subduction zones
- deep cuts in ocean floor
- on sides of island arcs “V”-shaped
- lower gravitational pull
- ~ 10 km deep
earliest continental crust
basaltic material melted and oceanic plates move down into hot mantle; small proto-continents form (Archean)
central rift valley
zone w/ frequent, shallow earthquakes bc of submarine mountain ranges
magnetic reversals
poles switch directions
- changes in orientation of earth’s magnetic field
- caused by change in magma flow through mantle
magma
molten rock
asthenosphere
deep, fluid layer of mantle (mostly molten rock)
3 plate movements
ridge push (“sea floor spreading”), mantle drag, slab pull (subduction)
what generates plate movement?
heat (convection) and earth’s forces
sea floor spreading
at mid-oceanic ridges, plates split
what occurs at mid oceanic ridges?
formation of new crust
- older rock spreads apart
mantle drag
lateral flow/friction b/w plate and mantle
- recycling of lithosphere
- pulls old lithosphere under, (so new can form in subduction)
subduction
denser plate slides down into magma, less dense plate covers the other
- when plates crash
- lithosphere recycling: when old plate goes under, gets heated by core, reused
what force drives subduction?
force due to the weight of the denser plate sinking (older)
- biggest drifting force
divergent boundaries occur at…
mid-oceanic ridges
- w/ sea floor spreading
- plates move apart
convergent boundaries occur at..
subduction sites
- subduction and collisions
transformation boundaries occur at…
major fault lines
- plates rubbing together
- linear faults
how old are todays continents
100 million years
order of 3 supercontinents:
oldest): rodinia –> panotia –> Pangaea
pangaea
life is introduced
- and adapts/spreads
laurasia
Pangaea splits –> N. supercontinent
gondwana
Pangaea splits –> S. supercontinent
rodinia
original supercontinent
- glaciation
- 1.1 billion years ago
- split 3 ways
panthalassia
1 global ocean during pangaea
pannotia
2nd supercontinent
- cambrian explosion of life
- 4 way split
- 2 large oceans form
- ~500 million years ago
ithsmas
small piece of land connecting 2 larger pieces of land
currently this is the __ period in earth’s history.
driest
epeiric sea/epicontinental seas
formed when sea level rise and falls
continental islands
island breaks off from continent
- easier access to colonize
oceanic islands
volcanic islands
- soil = high in nutrients
- longer time to colonize (less access)
- adapt/evolve more
surstsey
volcanic island exploded/appeard in 1960s
- 1964: 1st bacteria
- 1965: 1st vascular plant
- 2004: 400+ species
hotspots
weak spot in mantle where magma is released; oceanic plate subduction = volcano
hotspots form…
linear island chains
- older submerge, new appear
triple junction
where 3 plate boundaries meet
triple junction forms…
volcanic islands
global circulation patterns are controlled by…
equatorial pole gradients and movement of land/ocean currents
what drives weather patterns?
oceanic current
Pangaea ultimate theory
theory we’re moving toward another supercontinent
