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23 Cards in this Set

  • Front
  • Back
The Planet...
is always changing shape. Mountains are forming. Oceans are getting wider and rocks "disapear"
Layers of the Earth
Lithosphere: thin, solid, outer layer
Mantle: plastic like layer, solid, 80% of earth
Moho: boundry between mantle and crust
Outer core: only liquid layer
Inner Core: solid iron and nickle; 6000 degrees C
The Lithosphere (crust)
what you walk on. very thing compared to the rest of earth layers. 3-25 miles thick. broken into pieces called plates or tectonic plates. "plates" float on tectonic plates
The Lithosphere (cont.)
2 rock types
continental: granite, less dense
oceanic: basalt, more dense
The Mantle
Layer of dense, hot rock
semi-solid, can soften and flow: like plastic
1800 miles thick
high pressure softens rock
covections currecnts due to great temperature differences from top to bottom.
litospheric plates float on mantle
The Outer Core
the only liquid layer
mostly iron and nickel
spins as earth rotates and creates magnetic field
2,890-5,150 km thick
4,000-5,000 degrees C
The Inner Core
solid
mostly iron and nickel
5,000-6700 degress C
1,250 km thick (780 miles)
heat source-radioactive decay meteroite impacts and weight of overlying material
source of iron and nickel is meteroite
The theory of plate tectonics
in 1912, alfred wegner proposed that continents were moving
about 200 million years ago a supercontinent named Pangea began to break apart
Formed 2 landmasses, Laurasia and Gondwanaland
these landmasses continued to breaked apart into smaller contients that we have today
Evidences
1. continents fit together like a puzzle
2. mountain chain line up
3. rock layers and correlated may be correlated across ocean
4. mineral compostion along south ameria and africa match up
5. rocks of ocean basins are younger than continental rocks
Why do the plates move?
covection cells
due to density differences in mantle
warm plastic like rock in mantle rises cooler rock sinks
the combination of heat and pressure in the mantle causes the rock to be very mobile
plate motion is only a few centimeters per year
Divergent Boundary
plates move apart from each other
new rock is formed where magma exits crust
this is called a ridge
Divergent Boundaries (cont)
magma moves up the mid ocean ridge and spills onto the ocean floor creating new rock
this rock is basalt dense and mafic rich in iron and magnesium
this is known as seafloor spreading
Magnetic Reversals (evidence of seafloor spreading)
magnetometer: a device for measuring magnetiusm
notice rock on ocean floor magnetized in pattern of symmetrical stripes
alternating reverse and normal magnetism
Convergent Boundries
where plates collide or converge
3 types of convergent boundaries
1. subduction zone : dense, mafic, basatic ocean crust collides with less dense felsic, granitic continental curst. forms mountains, volcanoes, and ocean trenches.
alaska, washington, oregon alifornia,
mt. st. helens, mt. rainer
pafic ring of fire
Continental collisions
formation of moutain ranges as one contient collides with another
pushes continents upward and downward
extreme heat and pressure
high grde metamorphism
earhquake activity
example: himilayan mountains
Ocean to Ocean subduction
deep sea trenches
volcanic island arcs
earthquake activity
ex: indonesian islands, mariana islands
Transform boundary
one plates slides past another
marked by linear valleys, stream beds may be cut in half, each half may be moving in opposite direction
southern california, san andreas fault
San Fransico earthquake
ruptured the san andreas fult line for 296 miles. most damage from fire
Hot Spots
volcanic activity occurs in the center of plates. (away from the boundary)
rising magma melts through the crust
examples: hawaii, yellowstone
crustal changes
rock layers can be folded (bent or curved
faulted: displased along a crack due to movement of the lithosphere
titled
slanted
uplifted
raised up