plate tectonics + rocks

wegener’s five arguments

fit of the continents, locations of past glaciations, distribution of climate belts, distribution of fossils, matching geologic units

how does new ocean floor form?

continents rift apart, upwelling of magma reaches the surface and pushes continental plates apart

young ocean floor is located [closer to/farther away from] the MOR

closer to

the farther away you are from the MOR, the [younger / older] the ocean floor

older

common bathymetric features to identify an MOR

high point in elevation at the MOR, symmetrical decrease in elevation on either side

where is the MOR?

C

positive anomalies

magnetic north aligned with geographic north

negative anomalies

magnetic north aligned with geographic south

Where is the MOR 

point C

common paleomagnetic features to identify MOR

normal polarity, symmetrical banding on either side

newest seafloor corresponds to [upper/lower] rock in the geometric polarity timescale

upper

divergent boundary

two or more plates are spreading apart from each other

what force acts at divergent boundaries?

ridge-push

convergent boundary

when plates collide with each other

what happens at an ocean-continental boundary?

oceanic lithosphere subducts under continent

force during convergent boundaries

slab pull forces

what features emerge at a convergent boundary

trenches and volcanic arcs

hot spot

fixed spot in the mantle that forms volcanoes as lithospheric plates move across it

ridge push

gravity forces push new crust downwards, away from divergent boudary

slab pull force

dense ocean slab is pulled down by gravity, bringing ocean plate into the mantle and facilitating pulling oceanic lithosphere from MOR

true/false: slab pull forces also work on divergent boundaries

true

how do slab pull forces affect divergent boundaries

they facilitate movement of plates

true/false: youngest seafloor is at convergent boundaries

false

where are earthquakes found at divergent boundaries

concentrated at the boundary

where are earthquakes found at convergent boundaries

along the boundary and inland on continental plate

fit of the continents

continents look like they can fit like puzzle pieces

evidence for fit of the continents

maps, geography, edges, of the continents

locations of past glaciations

glaciations appear to have been originally connected in Pangaea

evidence for locations of past glaciations

striations, glacial till

striations

scratch marks left by glacier

distribution of climate belts

continents once occupied different climate zones

evidence for distribution of climate belts

specific flora/fauna

distribution of fossils

same fossils found in South Africa and South America

evidence for distribution of fossils

fossils

matching geologic units

same precambrian rocks found in multiple continents

evidence for matching geologic units

rocks, mountain ranges

minerals

naturally occuring (formed by a geological process), solid, orderly arangement of atoms and a definable chemical composition (inorganic)

crystalline

regular internal geometric shape

ways to form minerals

solidification, precipitation from water, diffusion, biomineralization, precipitation from gas

solidification

when minerals crystalize out of a fish

precipitation from water

when minerals crystalize from water

diffusion

atoms migrate and build mineral structures

biomineralization

when minerals crystalize from organisms

precipitation from gas

when minerals crystalize from a gas

how many classes are minerals grouped into

seven

where is the anion in the chemical formula

the end of the formula

where is the cation in the chemical formula

the beginning of the formula

silicates

SiO4/4 anionic group

sulfides

metal cation bonded to sulfide anion (S2)

oxides

metal cation bonded to oxygen aniona

halide

halogen or salt producing ion

carbonate

CO2 is anionic group

native metals

pure masses of a single metal

sulfates

metal cation bonded to SO4/2 anionic group

ways to identify minerals

color, streak, luster, hardness, fracture & cleavage