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Geology Midterm
terms
32
Geology
Undergraduate 2
10/04/2009

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Cards

Term
how old is the universe
Definition
15 by
Term
Scientific Method
Definition
Observation, hypothesis, test, theory...not fact
Term
Greatest % of Earth
Definition
Mantle
Term
Asthenosphere
Definition
1 earth is only planet with it, partially moltent zone, plasticy, 100km
Term
Outer Core
Definition
liquid molten material, 5000 km
Term
inner core
Definition
extremely hard, 6000 km, hot as surface of the sun but extreme pressure so is hard
Term
Lower Mantle
Definition
rigid solid body, moves like a plastic and stretches, 1000km
Term
Upper Mantle
Definition
two parts
Term
lithosphere
Definition
2 part of mantle & crust upper most mantle crust
Term
oceanic crust
Definition
basalt, dense rock, black, what errupts out of volcanoes, minerals: plagioclase, olivine, pyroxene, 5-10 km thick, 150 my
Term
continental crust
Definition
less dense, boyant makes up continents, granite, lighter in physical occurance, density and color less than oceanic, 20-100 km thick 3.8 by
Term
olivine and pyroxene
Definition
two most abundant minerals
Term
plates
Definition
lithosphere is broken up into plates that slide along on the asthenosphere
Term
Divergent plate boundary
Definition
moving away generating new plates (volcano, mid ocean ridges)
Term
convergent plate boundary
Definition
come otgether (trench) destroys plates subduction zones (aleutian islands)
Term
transform plate boundary
Definition
slide past eachother, neither created or destroyed, san andreas fault, earthquakes but no volcanoes
Term
Divergent crust
Definition
5 km thick and grows to 25 km thick creates one continuous volcano chain of them
Term
MOR
Definition
most active volcanoes...divergent
Term
istostasy
Definition
crust weighs down on the lower lithosphere but rebounds causing erosion
Term
trench
Definition
deepest part of Earth, oceanic is more dense so subducts
Term
oceans enable earth to...
Definition
have melting and subducting zones
Term
volcanic arcs
Definition
convergent boundaries, parallel to trenches on overriding/host plate
Term
what drives plate techtonics
Definition
unknown, convection? push at divergent and pull at convergent
Term
earthquakes
Definition
occur at all boundaries, but most dangerous at tpb because shallowest area
Term
Wallace Creek
Definition
proof of tpb and shifting of plates because theres a bend in it
Term
# of plates and rate at which they move
Definition
about 20 plates that move continuously at 15 cm /year
Term
Wadati-Benioff EQ
Definition
reveals plate decent, marks frictional contact and mineral transforms, EQ deepen away from trench...EQ stop below 660km
Term
what happens to old plates as they descend?
Definition
unknown...melt at about 150 km deep...lower mantle may be a plate graveyard
Term
MOR axis
Definition
offset by transform faults...geometric necessity for a line spreading on a sphere
Term
Alfred Wagner
Definition
German who proposed pangea; continents fit together, glacial locations, fossil organisms, rock type placement, structural similarities, paleoclimates preserved in rocks, ridiculed because lack of mechanism for drift
Term
debate of plate techtonics returned in 1950 because...
Definition
WWII submarines, ocean floor was not flat
Term
Hot Spots
Definition
volcanic plumes independent of techtonic plates, mafic magmas from lower mantle, line of sea mounts indicate direction or plates
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