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Historical Geology 1
Historical Geology 1
87
Geology
Undergraduate 1
02/20/2012

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Term
body waves
Definition
penetrate deep into earth
Term
discontinuities
Definition
where seismic waves experience an abrupt change in velocity
Term
mohorovicic discontinuity
Definition
boundary between upper crust and mantle
Term
gutenberg discontinuity
Definition
outer boundary of the core
Term
s-wave shadowzone
Definition
where s-waves dont travel through, 105 degrees
Term
p-wave shadowzone
Definition
105-140 degrees, where P-waves slow down
Term
fault
Definition
a break in Earth's crustal rocks
Term
normal, reverse, lateral faults
Definition
hanging wall is lower, hanging wall is higher, strike slip fault
Term
folds
Definition
bends in rock strata
Term
how folds are measured
Definition
strike, compass direction of line w/ horizontal plane
dip, angle from joint plane to horizontal plane
Term
types of folds
Definition
anticline, uparched layer rocks
syncline, downwardly folded rocks
monoclines, single bend in a horizontal strata
Term
domes and basins
Definition
like anticlines and synclines, but in elliptical to circular shapes
Term
suture zone
Definition
where two continental crusts collide
Term
ridge push and slab pull model
Definition
since spreading centers are high on the ocean floor, they force oceanic crust below continental crust
Term
differentiated
Definition
distinct layers, core mantle crust, based on density
Term
magma ocean
Definition
how the earth was during the archean
Term
komatiites
Definition
rocks that formed from the cooling magma
Term
hydrologic cycle
Definition
water cycle
Term
shield
Definition
oldest part of a continent
Term
platform
Definition
where shields are blanketed by sediment
Term
granulite
Definition
largely gneisses, derived strongly from strongly heated and deformed granitic rocks
Term
greenstone
Definition
volcanic rocks along with metamorphosed sediments
Term
metazoan
Definition
multicellular animals that possess more than one kind of cell, have their cells organized into tissues and organs
Term
requirements for sediment deposition
Definition
supply, basin
Term
terrestrial sediment environments
Definition
lakes, rivers, alluvial fans
Term
lacustrine deposits
Definition
lakes, coarse at shoreline, fine at center
lenticular(thin towards the edge)
Term
alluvial fan
Definition
gravity and
water deposits that occur
along the margins of
mountainous regions where
the steep topography meets
the flat plains.
Term
bajadas
Definition
alluvial fans spilling out of ravines from a mount front
Term
fluvial
Definition
rivers, sediments of all sizes
Term
cross-beds
Definition
common sediment structure in fluvial sediments
Term
marine sediment deposits
Definition
continental shelf, slope and rise, abyssal plain
Term
continental shelfs
Definition
shallow marine area
Term
slope and rise
Definition
steepest part of ocean floor
Term
turbidity currents
Definition
as the sediments descend, it mixes with water and forms a cloud
Term
history of physical earth
Definition
geography, topography, climate, atmosphere
Term
history of biological earth
Definition
how organisms change, adapt, move
Term
rock forming minerals
Definition
all rocks are composed of one or more minerals
all minerals have a particular crystal comp and structure
Term
most common mineral
Definition
SiO2, quartz
Term
Unit Cell
Definition
determines the shape of mineral
Term
common mineral shapes
Definition
cubic and hexagonal
Term
unique properties of a mineral
Definition
chemical formula, crystal structure, hardness, density, color, cleavage, melting point
Term
mineral classes
Definition
either silicate or non silicate
Term
how minerals form
Definition
melt, precipitation, solid state diffusion
Term
What determines which elements form which minerals?
Definition
availability of elements, temperature
Term
igneous, sedimentary, metamorphic rock
Definition
solidified from melt
detritus
solid state diffusion
Term
how sed. rocks form
Definition
on surface, normal pressure and temperature
Term
metamorphic textures
Definition
foliated - crystals align parallel
nonfoliated - they dont
Term
Geochronology
Definition
how you tell the age of rock
radioactive decay
radiometric dating
Term
how do isotopes occur in rocks?
Definition
locked in when crystal forms
Term
half-life
Definition
.693/lamda
Term
determining the age of a rock through half life
Definition
1/lamda multiplied by ln([d/p]+1)
Term
clast
Definition
small fragments
Term
things all sed. rocks have in common
Definition
deposits of eroded/weathered remains of other rocks
transported and deposited somewhere else
once deposited, undergo compaction and lithification
Term
clastic sedimentary rocks
Definition
tiny bits and pieces of rocks
Term
minerals we find...
Definition
most stable, stand up to weather the best
Term
type of raw sediment
Definition
1. little weathering
-many different minerals
-jagged pieces
-large pieces
2. alot of weathering
-well sorted
-rounded
-stable minerals
-smaller pieces
Term
sizes of clasts
Definition
conglomerate>sandstone>siltstone>claystone
Term
ways sediment is transported
Definition
wind, water, ice, gravity
Term
graded sediment
Definition
when the finer sediment is layered on top of the coarse sediment
Term
Types of sediment strata
Definition
bed - more than 1 cm
lamination - less than 1 cm
Term
types of carbonate
Definition
calcite - limestone
dolomite - dolostone
Term
types of evaporites
Definition
halite
gypsum
Term
fossilization
Definition
long term preservation of organic remains
Term
fossils are usually found in...
Definition
clastic sediments - mud and sand stones

lakes, rivers, ocean

unusual materials - amber, frozen, peat bogs, tar
Term
how fossils are formed
Definition
become buried
conducive fossil environment
Term
5 layers of earth
Definition
crust>upper mantle>mantle>outer core>inner core
Term
p-waves
Definition
primary/compressional waves
particles move same direction as energy
can travel through solids and liquids
Term
s-waves
Definition
secondary or shear waves
particles move perp. to energy
only thru solids
Term
properties of waves
Definition
speed P>S>Surface
feel first P, S, Surface
Term
how density affects absolute speed of waves
Definition
the denser the rock, the faster they travel, because the atoms are closer
Term
lithosphere
Definition
outer shell of earth, crust and upper most mantle
Term
asthenosphere
Definition
below lithosphere
Term
thickness of crust varies in...
Definition
oceanic
Term
Pangea
Definition
Early jurassic super continent
Term
hot spot
Definition
when aesthenosphere rises within a plate boundary
Term
oldest whole rock
Definition
quebec, greenstone belt
4.28 byo
Term
oldest minerals
Definition
zircon, australia
4.4 byo
Term
when the poles reverse
Definition
4-5 times per million years
Term
early atmosphere
Definition
many things, but no free oxygen, so no ozone, so very high UV
Term
miller and urey experiment
Definition
methane and ammonia gas and water in a test tube, heated and electrified, amino acids form
Term
Isua Formation
Definition
first sign of life, high 12c/13c ration
-organisms like 12c for building
-only carbon used for building life has 100/1 ratio that the isua formation had
Term
Isoprene
Definition
another early sign of life
-normally found in organism to make cell walls
-methanogen
Term
cyanobacteria
Definition
3.5 bya, formed stromatolites, which are alternating mounds of sediment and cyanobacteria
-uses photosynthesis to consume CO2 and form O2(free oxygen)
Term
Changes because of oxygen - iron
Definition
turns ferrous iron(no O2) to ferric iron (oxidized iron), because it oxidizes the iron in the water and it precipitates out
Term
prokaryote
Definition
simple, no nuclei, bacteria + cyano bacteria
Term
Eukaryote
Definition
complex, have nuclei, have organelles
Term
locations of banded iron formations
Definition
australia, south africa, north america
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