Geog 2051 ch 11
Terms
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- Four units of time from biggest to smallest
- Eon, era, period, epoch
- Last three era's and first Eon
- Cenozoic, mesozoic, paleozoic, Precambrian
- Age of earth, percent of time in past three eras
- 4.6 bil, 1.4% cenozoic, 4 mesozoic, 6.3 paelozoic, 88.3 precambrian
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Dating
two types -
Relative – sequence, leads to stratigraphy, based on fossils
Absolute – number of years, based on radiometric dating - Fundamental principle in geologic time scale is:
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uniformitarianism
“the same physical processes active in the environment today have been operating throughout geologic time - in cooling, elements sorted by
- density, iron to middle, silica to top
- Layers going in
- lithosphere, asthenosphere, upper mantle, lower mantle, outer core, inner core
- make up of upper and lower mantle, outer and inner core
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olivine, silicate minerals
olivine iron magnesium silicates
liquid molten iron
solid iron - lithosphere is?
- Crust and uppermost mantle
- two discontinuities?
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Mohorovicic crust/mantle
gutenbert mantle/core - two types of crust and props
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continental: lighter thicker
oceanic denser thinner - isostasy?
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buoyancy and balance of crust on liquid inner earth
More weight above pushes crust into uppermost mantle and it into - sedimentary are what % of crust and surface, igneous are what %
- sedimentary are 5% of crust and 75% of surface, igneous are 95% of crust and 25% of surface
- classification of intrusive
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I. pluton: any intrusive
A. batholith: largest
B. magma conduits
1. sills: parallel to sedimentary
a. laccolith: lens shaped sill
2. dikes: form across sed layer - one type of extrusive, intrusive
- basalt, granite
- two types of igneous by composition
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felsic: feldspar and silica, lighter less dense
mafic: mg and ferric, darker and denser - four kinds of sedimentary rock and root material
- sandstone, shale: mud, limestone: little animals, coal: plants
- lithification
- process of compaction, cementation, and hardening of sediments, also chemical prepitation
- two types of sedimentary and formation
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clastic: transported rock fragments
chemical: precipitates of minerals: limestone - foliated:
- metamorphic rock that shows patterns or lines from particular alignment of minerals
- 5 metamorphic transformations
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shale ->slate
granite/shale/slate -> gneiss
basalt/shale/peridotite->schist
limestone/dolomite->marble
sandstone->quartzite - Alfred Wegner came up with: 2
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continental drift
pangea
scientific evidence of both - plate tectonics make
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volcanic activity
upwelling of magma
crustal plate movement
crustal changes
earthquakes
subduction of crust
sea floor spreading - seafloor spreading dated by?
- magnetic orientation of new crust
- which goes under when ocean hits continent crust?
- ocean bc its denser
- two parts of geologic cycle
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exogenic: tearding down powered by solar energy
endogenic: building up, internal heat powered - at least how many plates
- 14
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fracture zone
fracture fault -
moving in same direction
different directions