meteor
flash of light caused by an extraterrestrial object entering the atmosphere
meteoroid
actual object entering the atmosphere
meteorite
object once it reaches the ground
importance of minearls
historial tool for geologists---record history of pressure, temperature, composition, and time; they are the building blocks for rocks
definition of minerals
naturally occurring
inorganic solid-some minearls have carbon
orderly crystalline structure-ice is a mineral but liquid/gas water is not
well-defined chemical composition
atoms
building block for minerals. as ions with similar ionic radius fit better together. bonding behavior is controlled by valence electrons and ionic radius
most abundant element in the solar system
hydrogen, followed closely by helium
crust vs mantle
more silica in crust than mantle while the mantle has more magnesium
the main difference between minerals
the different ratios of silicon to oxygen
1:4-independent, single tetrahedron-olivine
1:3-single chain-pyroxene
4:11-double chain-amphibole
2:5-sheet structure-mica
1:2-3d network-potassium feldspar
mineral identification
1. color
2. harness using the Moh's Hardness scale (1 is soft, 10 is hard)
3. luster-shininess
4. cleavage-the way it fractures
oceanic vs. continental crust in density
less dense continental floast on denser oceanic crust
what group is most abundant in crust
feldspar-potassium and plagioclase
quartz
extremely hard, pyramid shape crystals
amphibole
hornblende, tremolite
mica
muscovite (white), biotite (black)
clay minearls
kaolinite
pyroxene
enstatite (orthopyroxene), dipside (clinopyroxene)
rocks without silicon (non-silicates)
oxides, sulfides, sulfates, halides, carbonates
overview of minerals
1. formation of minerals is controlled by availability of atoms
2. abundance of SI and O in crust and mantle means that most minerals are constructed from silica tetrahedra
3. silica tetrahedral combine in different ways depending on silica and oxygen rat
liquids to make igneous rock (2)
2. lava-material in liquid form that is exposed at Earth's surface
1. magma-contained in depth
solid of magma/lava (1)
igneous rock=cooling of lava or magma
two types of igneous rocks
1. intrusive-cooled at depth and remains in earth's interior-large grained bc cool slowly
2. extrusive-cooled at surface-fine grained bc cool quickly
texture of igneous rocks (4)
1. aphanitic-extrusive, fine grained
2. vesicular-extrusive, shapes of gas bubbles preserved in crystallized rock
3. glassy-extrusive
4. phaneritic-grains are easily visible-intrusive
continental crust is silica
rich (felsic to intermediate)
oceanic crust if silica
poor (mafic)
mantle rocks are silica
poor (ultramafic)
to melt rocks, need to
increase temperature
decrease pressure
increase volatile content-change chemical composition
solidus
when little bits of melted rock form
liquidus
everything's liquid once you get there
partial melting
in btween solidus and liquidus
flux melting
subduction of oceanic lithosphere under continental crust. water goes from crust into mantle rocks--> lowering melting temperature-->melting of rocks and forms continental volcanic arc
decompression melting
at spreading centers, partial melting of hot mantle rock when it moves upward and the pressure is reduced to the extent that the melting point drops to the temperature of the body
bowen's reaction series
low viscosity-low silica-HIGH in melting temperature, crystallize first
high viscosity-high silica-in LOW melting, minerals with high silica content crystallize last
xenoliths
magma composition; inclusions of host rock that survive
forming continental crust (5)
1. partial melting in the upper mantle produces mafic magma
2. rises upwards through the lithosphere
3. pools at the base of the continental crust, which is less dense than mafic magma
4. differentiation of the magma chamber produces intermediate melts
5.
sills
igneous, horizontal traveling of magma
dikes
igneous, vertical (typically along fractures) traveling of magma
lacolith
igneous. when dikes travel up and create magma balloon that rips through the sedimentary layer. looks like a hill created by magma
pluton
igneous, single magma chamber that has crystallized, can be exposed by erosion
batholith
when lots of plutons are together and exposed at surface
felsic (igneous)
granite, rhyolite, forms at low temperature, last to crystallize
decreasing potassium/sodium
intermediate (igneous)
andesite and diorite, decreasing silica, low middle temperature-middle to crystallize
mafic (igneous)
basalt and gabbro, increasing iron and magnesium and calcium, high middle temperature-middle to crystallize
ultramafic (igneous)
olivine and peridotite and komatite, forms at highest temperature-first to crystallize
types of magma (2)
basaltic-silica poor, low viscosity, easy for gas to escape
rhyolitic-relatively silica high, high viscosity, difficult for gas to escape
3 V's of volcanology
viscosity, volatiles-chemical elements with low boiling points associated, volume-volcanic explosivity index
as magma cools, the silica content
gets higher because high silica content crystallize first
shield volcanoe
Mauna Loa
gentle, broad, sloping shape,
volume is enormous
flood basalts
low silica content,
much larger in terms of volume than shield volcanoes-eruptions much longer
cinder cones
medium-high volatile content, mono-genetic volcanoes erupt once, volcanic tuff makes up the walls of the volcano (volcanic ash), cinder cones are short lived
stratovolcanoes
pointy, style of eruption changes over the life of volcano (what volcanoes are pictured as)
calderas
most explosive made with remnant of past volcano, formed by a collapsing magma chamber and a lake forms around it
anatomy of a volcanic eruption (stratovolcano)
1. oceanic lithosphere subducts beneath continental lithosphere
2. at depth about 100 km, amphibole dehydrates and water is released into the mantle-->lowers melting temperature
3. melt starts to percolate upwards into volcanic system
4. when mantle melts
Aa
lava-slow moving, viscous with shiny/sharp crust
pahoehoe
lava-fast moving, lumpy or ropy texture
pillow lava
lava, erupted and cooled underwater
lava fountains
non-explosing outpouring of lava
lava flows
rivers of lava downhill--flows can be gentle or fast moving
fissure eruption
the eruption of magma out of a crack in the lithosphere, rather than from a single pipe or vent
lava lakes
long lived pools of lava, lake fed by magma chambers below with perfect balance between heat from below and cool air in atmosphere
lava tubes
surface cools but lava is insulated below ground--produces underground rivers
pryroclastic debris (from volcano)
solid while aireborne-ash, cinders, blocks
liquid when aireborne-bombs (largest)
ash
pryroclastic debris. fine granular material and has effect on climate-dangerous for air travel because it adheres itself to plane turbines
pyroclastic flow
pryroclastic debris. temperature is incredibly high and moves fast as it moves with gravity. they follow stream beds (where many people live)
causes of pyroclastic flow (3)
1. volcanic domes
2. collapsed crater rims
3. direct blast
volcanic domes
unstable edifices of rock that build up slowly
lahars
many volcanoes are covered with snow and ice year-round. when hot volcanic materials and glaciers mix, a dense river pours down side of volcano--> mudslide
Mount Merapi
smoke and ash at the beginning-->small frequent earthquakes caused eruption-->landslides caused by magma swelling and changed slope of the sides
Mount Vesuvius
stratovolcano. not complete cone because caldera that used to large ancient stratovolcano named Mount Somma--> vesuvius formed in side the large original volcano
eruption destroyed Pompeii by pyroclastic flow
Pliny the Younger was the only witness
Mount Saint Helens
eruption caused collapse of mountain. earthquake--> eruption--> ash fall in 11 states-->lahars
changed america's mindset about eruptions
phretic eruptions
explosions of steam from interactions og magma and groundwater
weathering
the physical breakdown and chemical alternation of rock at or near the Earth's surface, sources of rock
erosion
the physical removal of material, transport processes
mass wasting
the transfer of rock and soil downslope under the influence of grcity, transport processes
frost wedging
mechanical weathering, crack in rock-water get ins and it freezes. ice increases in volume and the crack gets bigger. when the ice melts, then ice gets in once again in the winter and makes the crack bigger again.
types of weathering
1. mechanical-physical forces break rock into smaller peices
2. chemical-transformation of a rock or mineral to a different composition that is more mobile than the original. more susceptible to this weathing if increased surface and smaller blocks
salt crystal growth
mechanical weathering, Dead Sea-salt crystals grow while water evaporates
biological weathering
mechanical weathering, roots break up rocks
sheeting
mechanical weathering, deeply buried igneous pluton suddenly uplifts and erodes overlying rock
exfoliation
mechanical weathering, peeling off in sheets rather than eroding grain by grain
role of acids in chemical weathering
most rocks are not very soluble in water, however small levels in acidity in water will greatly enhance weathering, carbonic acid in rain or ground water will dissolve calcite
spheriodical weathering
chemical weathering, water streams inside rock, weathering causes them to separate, and then weathering also makes them round
oxidation reactions
chemical weathering, reaction when pyrite (iron sulfide) reactions with water to generate limonite (rust) and sulfuric acid --> acid mine drainage. looks like gold but its pyrite--> produce tons of sulfuric acid when water hits it and water leaches into s
sedimentary rock
formed by the settling of minerals derived from weathering and erosion, or biological process
ex: Grand Canyon
origins of sedimentary rocks
1. weathering-mechanical and chemical
2. transport-river (fluvial) ocean, glacial, aeolian (wind-driven)
3. deposition-settling (ex: sand in water, larger particles settle first), chemical changes
4. diagenesis-burial, lithification (turning something int
types of sedimentary rock
1. detrital-composed of grains of minerals already broken up
2. chemical-derived from ionic material
3. organic-classified using composition and texture
detrital sedimentary rock
(transported) matt material (called cement)
lots of weathering, lots of deposition-when we weather felspar, detriral sedimentary rocks are classified by grain sized, grain shape, and the distribution of grain size
classify detrital sedimentary rock
size range, sorting, angular and sphericity
conglomerate/breccia
texture is coarse, gravel rounded or angular, poorly sorted
caused by high energy process
breccia-haven't travelled such large distances, particles are sharp
sandstone
texture is medium, sand, detrital sedimentary rock, permeable
siltstone
texture if fine, mud, detrital sedimentary rock
shale or mudstone
detrital sedimentary rock, texture is very fine, mud
the differences in sedimentary rock depends
on how far the rock has traveled, the environment in which it lies--> factors of erosion
shale special characterisitic
impermeable caprock that seals off the top-oil can be stored underneath
Burgess Shale
major discoveries of the Cambrian period-fossils
Marcellus Shale
hydrofracking-controversial
crystalline limestone
calcium, calicite, organic sedimentary rock
biochemical limestone
corals and many other deep sea creatures secrete carbonaceous exoskeletons.
fosfillferous limestone
made of fossils
calcium compensation depth
sedimentary rock forms at less than 5,000 meters
evaporite deposits
mineral that was dissolved in water and when the water dried up, the mineral is deposited
ex: halite, salts, sulfate, carbonates, borates
environments for sediments
swamp, glacial deposits, beach sands, lake, allurial fans
-crossheds-aoliean, usually found in desert
-lake-low energy-shale
-glacial-high energy
-allucial fans-poorly sorted
sedimentary facies
sandstone-shale-limestone
protolith
what was the rock before metamorphism, the rock that existed before metamorphism
metamorphism
transformation of one rock type into another through the imposition of temperature, pressure, chemical changes, and/or stress
DOESN'T INCLUDE: changes due to weathering/erosion and due to complete melting
agents of metamorphism
1. temperature
2. pressure-forces applied equally in all directions
3. fluids
4. stress-forces applied differently depending on direction
polymorphs
same chemical elemental structure but different physical structures because they went through different metamorphic reaction. same chemical composition but different minerals
if you find a rock with both types of polymorphs
it occurs at a point in pressure vs. temperature where both types can occure
stress brings about foliation
1. grain rotation
2. change of grain shape
3. formation of new elongated grains
burial metamorphism
similar to diagenesis. burial--compaction--greater burial--more compaction
thermal metamorphism
host rock next to the magma chamber is heated and produces a metamorphic aureole and igneous pluton
shock metamorphism
huge impact. high pressure and low temperature next to subduction zone
hydrothermal metamorphism
hot, iron rich fluids circulate through cracks in rocks-->changes the chemical composition of rocks, usually at mid-ocean rides at the formation of oceanic crust
regional metamorphism
occurs over broad areas of crust, usually in areas that have undergone deformation during an orogenic event resulting in mountain belts that have since been eroded to expose the metamorphic rocks
hydrolic cycle
the processes by which "water evaporates from the ocean, plants, and soil, moves though the atmosphere, and eventaully falls as precipitation" and falls into rivers and streams and be returned back to the ocean
habitability zone
the regions within a specific solar system in which liquid water can be stable
extends from earths out to mars
5 factors in runoff vs. infiltration
1. amount of water already in soil
2. intensity and duration of rainfall
3. surface material (ex: asphalt)
4. slope of the land (flat vs steep)
5. extent and type of vegetation (easier for water to penetrate soil if lots of vegetation is present, plants b
runoff
starts with sheet flows, turns into rolls, then gullies, then streams/rivers
advantage of channelized flow
less contact with the ground, water will move faster because of less friction with surroundings
streams
long-lived channels in depression in a surface caused by erosion
thalweg
deepest part of stream
scarp
side of the stream
head
start of the stream
mouth
end of the stream
4 basic controls on flow speed of streams
1. channel gradient-change in elevation over distance
2. channel size and shape-deeper narrow and uniform streams is faster
3. channel roughness-smoother steams are faster. barriers are slow
4. total discharge-more discharge is faster-more water stream ex
while traveling from headwaters--> mouth
channel roughness/channel slope typically decrease. discarge, channel size, flow velocity typically increase
zone of production
erosion is faster than deposition-taking mass out of this part of the river system
zone of transportation
rate of erosion and rate of deposition exactly the dame (no metrial being added or taken away in river system)
zone of deposition
close to the mouth of river. adding mass that has been transported
stream erosion-3 main mechanisms
1. abrasion-caused by sediment scouring away at the underlying rock (sand on stream floor)
2. corrosion-combination of weathering and erosion that involves chemical reactions (carbon dioxide and water create carbonic acid)
3. quarrying-river can pick up a
streams transport material
in solution (dissolved load), in suspension (suspended load), by sliding or rolling (bed load)
suspended load
competition between flow velocity and settling velocity-particles want to sink, but velocity of river determines if they remain suspended
rate that a particle settles is determined mainly by its diameter
bed load
transported by sliding or rolling underwater larger particles, rocks
saltation-in-between sliding and suspended
stream capacity
1. capacity-maximum load of material transported per unit time
2. competence-maximum particle size that can be transported by a river (more energetic rivers have higher stream capacity/competence)
development of river delta
channel gets clogged, then becomes filled in, provess repeats
tributaries
streams feed into one river
alluvial fans
alluviums drain and deposited at base. will know that water drained off steep mountain, periodic/incremental, typical arid climate
drainage basin (2)
1. sedimentary basin-low-lying geographic province that is filling with sediment
2. drainage basin-a bounded region that drains all of its water out of a common exit point
divide
direction of which water fall
separation of drainage basin
young stream valleys start off
v-shaped, created by rapid downward erosion, little deposition
valleys caused by glaciers characterisitic
u-shaped
base level
lowest elevation that the stream can possibly follow (minimum gradient)
influences on base level
they will try to work back towards base level, when you put a dam. the top of the dam becomes the minimum base level and the gradient of the stream goes down-->the energy of the stream decreases-->can't carry as much sediment and deposit the sediment-->cr
delta will erode because
not eough sediment reaches the delta but filling up the upper part of the river with sediment--> need to constantly dredge the river reservoirs tend to evaporate more
niagara falls
fault--> uplift --> migration of nik point
braided channels
when the source of water is very varied. ex: melting glaciers because they only provide water in summer months
meandering channel
natural consequence of motion of rivers, caused first by small wiggles in rivers and by times the wiggles grow, the water outside curve moves faster than the water inside the curve and has more erosional capacity-->the farter part of the curve cuts the la
oxbow lake
path of the river becomes much longer-->gradient becomes smaller-->river moves slower
but sometimes the river cuts off the long meander --> create an oxbow lake
incised meander
meander river cuts bedrock ex: colorado plateau, the uplift of the bedrock-->river cut the bedrock that went up-->the meander river shape is now fixed
terraces
tectonic uplift causes terraces-the previous floodplains rises up
ex: post glacial melting-land rebounces up
formation of floodplain
floodplain is formed from the windshield wiper motion of meander channel formation/cut off/destruction
rocks in floodplains-natural levees have coarse grained rocks. silt, clay, small grained rocks as you go farther out of the floodplains
levees
manage flooding-natural and artificial levees but their consequences: without flooding, the river doesn't deposit sediment onto the floodplains--> need to constantly dredge the river
areas with well developed levees pushes water to areas with less develop
bedrock channel
cutting into underlying rock
alluvial channel
cutting into unconsolidated sediment-alluvium
groundwater
liquid water that has infiltrated the outermost layers of the crust, contained mainly in pore spaces and fractures
surface water makes up about **of the water we use
3/4
porosity
fraction of the rock volume that is open space
permeability
ease with which fluids can pass through a rock
solutions to groundwater contamination
1. abandon water supply
2. attempt to pump out and purify water
3. clean up the source of pollutant and wait
subsidence
can come from mineral dissolution, mining, groundwater extraction
down-opposite of uplift
4 main categories of mass movement
falls, flows, slides, subsides
effect of friction on mass movement
Friction resists sliding. Friction is less than or equal to gravity (cannot be greater than)
creep
slow mass movement. Happens on hillsides that expand and contract.
3 points for forces
1. adding mass
2. agitation-ground shaking and falling down. ex: mudflows after earthquakes
3. changing the angle or shape of the slope-tectonic uplight. undercutting
tectonic uplift
� Steeper hill-slopes means more gravity and less friction
� Angle of repose: piles of material cannot exceed a critical steepness; maximum steepness is the angle of repose
undercutting
holes, caves in the ground caused by erosion (usually water erosion) of material at the base of a steep cliff
karst topography
many sink holes-come from undercutting, holes underground and surface collapses. sinking streams, erosion from river
3 factors to destabalize landscapes
erosion, weathering, and tectonic forces which leads to mass movements
why do people build on hillsides
no more room anywhere else
nice view
stay out of flooding
chemical dissolution
� Most rocks not very soluble in water
� But small levels of acidity in the water will speed weathering
� Carbonic acid in rain or GW creates caves/caverns
falls
(mass movements) free fall, dominantly vertical, move as separate blocks
flows
(mass movements) flow over landscape, more as viscous fluids, turbulance with moving mass
slides
(mass movements) slides on top of basal slip surface move as a semisolid mass
subsidies
collapse into void. dominantly vertical downward movement. move as separate blocks
mass movement
exchanges between gravitational potential energy and kinetic energy
example of cinder cones
owens valley
example of stratovolcanoes
mount shasta, CA
mount rainer, WA
example of caldera
crater lake, OR
exampe of lahars
nevado del ruiz
felsic
silica high, granite and rhyolite
intermediate
diorite, andesite, middle-high silica concentration
mafic
gabbro and basalt, middle-low silica concentration
ultramafic
silica low concentration, peridotite and komatite
more silica also means
more potassium and sodium
less iron, magnesium, and calcium
increasing explosiveness of volcanoes
shield (lowest), flood basalts, cinder cones, stratovolcanoes, caldera