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Geology

Terms

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luster
appearance or quality of light reflected from the surface of a mineral; metallic and nonmetallic
pahoehoe
a lava flow with smoothh to ropy surface
Moh's hardness scale
measures hardness from 1 to 10
talus
accumulation of rock debris at the base of a cliff
Nonsilicates
ex-calcite, dolomite, halite, gypsum, oxides
driving forces for plate tectonics
convection cell, ridge push, slab pull
Coal
organic. Lignite, biuminous, anthrocite
cobble
64-256mm, forms conglomerate or breccia
glassy
no crystals, high silicate content
Halite
Evaporite, NaCl
clay minerals
when light or dark silicates react with water at the surface, sheetlike structure, impermeable
magma
underground, contains volatiles-CO2, H2O, SO2
Intrusive rocks
igneous activity that occurs below the surface, take longer for it to cool
block lava
lava with a surface of angular blocks, andesitic and rhyolitic composition
progression of foliated rock types
shale, slate, phyllite, schist, gneiss, amphibolite
ice wedging
water gets in cracks in rocks, freezes and expands
viscosity
resistance to flow
Palezoic era
ancient life, 540-817 million
Atmosphere
gases that surround the earth
strain
an irreversible change in the shape and size of a rock body caused by stress
convergent plate boundaries
a boundary where two plates move together, oceanic sinks beneath continental
crystal settling
as magma crystallizes the minerals that formed earlier are denser than the liquid and settle out
metamorphic rock
changing of the rock, recrystallizatino due to pressure, temperature, pore fluids, and it depends on the parent rock type. the rock must remain solid
dark/ferromagnesian/mafic minerals
iron and magnesium, dark colors, ex-olivine, pyroxene, amphibole, mica (biotite)
Cementation
material precipitates from water that percolates through the sediment, open spaces are filled and particles join together. calcite, silica (makes it very hard), iron oxides (reddish/orange tint)
phanerozoic eon
541 million years ago. "explosion of life"
Aphanitic
microscopic crystals, vesicles-gas bubles, extrusive
calcite
in limestone, CaCO3
transform plate boundaries
a boundary where two plates slide past one another without creating or destroying lithosphere
turbidity current
a downslope movement of dense, sediment laden watercreated when sand and mud on the continental shelf and slope are dislodge and thrown into suspension
angular conformity
an unconmfomity where the older layers are at a differnt angle than the younger rocks
foliated texture
leafy, layered appearance.
minerals
can't be man-made, can't be organic, must be a solid and have a crystalline structure, its composition must be w/i a range but it can vary w/i the range
sheeting
outer surface of rocks will break off due to reduction in pressure fom where it formed
cleavage
place between patterns where a mineral can easily break apart
tyeps of radioactive decay
alpha, beta and gamma
Steps required for formation of Sedimentary rocks
Weathering, transportation, deposition, cementation
Hot spots
hot mantle is near the surface
crust
inner layer of earth's compositional layers, made up an iron-nickel alloy, magnetic field
oceanic crust
basaltic, thinner, much younger, denser than continental
Gypsum
CaSO4 2H20
Four components of soil
mineral 45%, humus 5%, water and air 50%
original horizontality
layers are put down horizontally
mantle
82% of earth's volume, middle layer of earth's compositional layers
sand size
1/16-2mm forms sandstone
Extrusive rocks
igneous activity that occurs at the surface
mesophere
pressure is high so it acts like a solid
hydrolysis/acid hydrolysis
reaction between water and minerals and acids
soil horizons
O (organic), A (humus), E (bleached and leached, no organic left), B (subsoil that collects everything from E), C (partially broken bedrock)
Dolomite
CaCO3, some Ca are replaced with Mg,
pyroclastic texture
"fire broken", consolidation of individual rock fragments that are ejected during a violent volcanic eruption
specific gravity
density of rock to density of water
hardness
the ability of a mineral to scratch another, resistance to abrasion.
silicate minerals
95% of crust, made up SiO4 (-4)
correlation
fill in the gaps. use the criteria of mineral composition, sequence and thickness
regolith
layers of broken up rock, uppermost layer is the soil
detrital
rocks that form from the accumulation of materialsthat originate and are transported as solid particles derived from both mechanical and chemical weathering
Geomagnetic reversals
magnetic poles switch
streak
the color of a mineral in powdered form
boulder
greater than 256mm, forms conglomerate or breccia
lava
at the surface, lost volatiles
Mid-Atlantic Ridge
mantle welling up, pushing oceanic plates apart to form new oceanic crust
unconformity
interruption/break inthe record, gap in time
athenosphere
flows due to melting, allows lithosphere to move
inclusions
rocks that are included are older than the rocks that are including them
mantle plume
divergent boundaries where mantle is coming up
stress
force per unit area
Mic (Muscovite)
1 dimension cleavage-sheets
Igneous rock
rock formed from the recrystallization of magma
crystal form
the external appearance of a mineral determined by its internal arrangement of atoms
color
physical property of a mineral that is a good indicator but can easily lead you astray
Silt size
1/256-1/16mm forms shale, mudstone, siltstone
mesozoic era
417-65 million
fossil sucession
simpler life forms older than more complex life forms
dissolution
water dissolves rock
slab pull
the colder the rock the more dense it becomes so it sinks and pulls the rest of the slab along
cross cutting
whatever is doing the cutting is younger than what it is cutting through
Nonferrogmagnesian/felsic/light minerals
rich in Si, Al (3+), lower density/specific gravity, tend to be lighter colored ex- feldspar, Quartz, Mica (Muscovite)
ridge push
at the spreading centers, the elevation is higher so gravity pulls it down
biosphere
living things on planet
aa
a lava flow that has a jagged, blocky surface
Lithosphere
solid outer sphere of earth
deep ocean trench
deepest part of ocean basin; narrow, elongated depression of the sea floor
pumice
a light colored glassy vesicular rock formed from pyroclastic materials
Clay size
less than 1/256mm forms shale, mudstone, siltstone
superposition
layer on top is younger than the layer on the bottom
Crust
consists of oceanic and continental, one of earth's compositional layers
evidences for pangaea
general "fit", Fossils (Mesosaurus and Glossopteris), rock types and structures (appalachians), Paleoclimatic evidence (coal in us suggests it was once near equater and evidence of glaciers in australia and india), Paleomagneticism
continental
granitic, thicker, older, less dense than oceanic
Quartz
hard, SiO2
Canezoic era
65 to present, dinosaurs gone
magma mixing
altering the composition of a magma through the mixing of material from another magma body
pebble
4-63mm, forms conglomerate or breccia
assimilation
incorporating the rock surrounding the magma into the magma composition
Limestone
made up of Calcium carbonate, chemical origin-oolitic (spheres) and travertine. bio origin- coral reefs, coquina (shells), chalk
liquid outer core
allows for magnetic field
chert
SiO2, formed from Quartz
Pillow lava
lava extruded under water so it solidifies as soon as water hits it
solid inner core
allows for magnetic field
Scoria
vesicular ejecta that is the product of basaltic lava
convection cell
as convergent boundary pulls crust down, it cycles magma back up to the surface
Porphyrtic
Large (phenocrysts) and microscopic (groundmass) crystals
granule
2-4mm, forms conglomerate or breccia
Hydrosphere
the portion of earth consisting of water 71%
Pegmatitic
very large cystals, greater than 1 cm
Uniformitarianism
world that is seen today has the same processes as in the past and is a result of those processes
dolostone
pass Mg solution through calcite to exchange calcium for mg in CaCO3. formed from dolomite
divergent plate boundaries
boundary where two plates move apart resulting in the upwelling of material from the mantle to create new seafloor
Phaneritic
visible crystals, intrusive
Geosphere
solid earth
Chemical sedimentary rocks
consists of material that was precipitated from water by either inorganic or organic means
Feldspar
K feldspar- pink (orthoclase), Plagioclase feldspar-striations (Na (+) and Ca (2+)
pre-cambrian eon
before any significant life

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