Aarav Reddy
Chapter 2 :
Earth Processes
2.1 – Tectonic Processes
2.1.1 describe the structure of the Earth, limited to crust (oceanic and
continental), mantle and core
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core – innermost , dense sphere made of iron and nickel
o solid inner core
o liquid outer core
mantle – hot , semisolid , molten rock capable of slow movement
o viscous asthenosphere capable of movement and deforming at high temps
crust – outermost later of solid rock
o continental crust – thinner and denser ; made of basaltic rocks filled with
iron and magnesium
o continental curst – granite and similar rocks
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2.1.2 describe and apply the theory of plate tectonics, and the evidence
supporting the theory, limited to the geological matching of rock
formations, distribution of fossils and living organisms, paleomagnetic
stripes on the ocean floor and the jigsaw fit of the continents
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theory of plate tectonics : the lithosphere is divided into plates that are in float
independently and are in constant movement due to the viscous asthenosphere ,
and can cause ocean features to form
supported by evidence:
o the geology of rock formations matched
o coastlines fit together like a jigsaw
o fossils and organisms are distributed on coasts of many continents
o paleomagnetic stripes(reversals in Earth’s magnetic fields every 250K
years , due to new solidified rock having charged magnetite) due to
seafloor spreading
2.1.3 identify and describe the three types of plate boundary as
convergent, divergent and transform
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convergent boundary – tectonic plates moving towards each other
o form a subduction/destruction zone(dense , oceanic plate sinks
underneath less dense , continental plate)
o trenches , volcanoes , earthquakes , tsunami
divergent boundary – tectonic plates moving away from each other
o constructive zones - magma seeps through crust
▪ creates new seafloor , rock eventually moves →seafloor spreading
o mid – ocean ridges , hydrothermal vent , volcano , tsunami
transform boundary – sliding of plates against each other
o conservative region – no crust is destroyed or created
o great seismic activity due to friction between faults(small cracks) :
earthquake , tsunami ; abyssal plains
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2.1.4 explain how tectonic processes produce ocean trenches, mid-ocean
ridges, hydrothermal vents, abyssal plains, volcanoes, earthquakes and
tsunamis
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trenches – narrow , deep canyons in seabed
o form at subduction zones of convergent boundaries
o Challenger Deep in Mariana Trench
mid – ocean ridges – underwater mountain ranges with central valleys
o new crust forms due to the upwelling of magma that solidifies into rock at
constructive zones of divergent boundaries
o have volcanoes and hydrothermal events in between
hydrothermal vents – openings in the ocean floor where cold ocean water that
has seeped in the crust is superheated by magma underneath and forced out
o occur within mid – ocean ridges at divergent boundaries
o as water seeps through cracks of crust , magma dissolves minerals turning
them black and these minerals precipitate out of solution forming solids
that pile on each other which creates the chimney/vent for superheated
water and minerals(plume) to spew out of
abyssal plains – flat , sandy regions found between trenches and continental rise
o form due at divergent boundaries due to seafloor spreading and falling
sediment falling on rock creating smooth , flat plain
volcanoes – mountains with crater/vent where lava. hot vapor , gas , rock
fragments are forced through Earth’s crust
o at convergent boundary where pressure builds up between oceanic and
continental plates causing the crust to thin and magma to rise/erupt
o lava solidifies into new rock building a volcano , and sometimes islands
o Ring of Fire has high volcanic and seismic activity
o formed at divergent boundary where crust is thin
earthquakes – sudden energy release from crust’s movement
o when 2 plates at convergent and transform boundaries get stuck , the
pressure builds up until a plate releases its potential energy as a burst of
seismic energy
o caused by energy of volcanic eruption too
tsunamis – long , high – energy waves caused by seismic activity of earthquake
or volcano
o energy is released and displaces large volume of water , the water holding
onto the energy moves quickly until it slows down and grows
exponentially in height as it grows closer to the coast
*convection currents – fluid/air movement based on temperature/density :
warmer , less dense rock rises above colder , denser rock , and as rocks cool, they sink ;
happening in a circular cycle
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2.1.5 state that the water coming from hydrothermal vents is under
pressure, hot and rich in dissolved nutrients and that this forms the
hydrothermal vent plume
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plume – the superheated , pressurized water rich in dissolved nutrients that
comes from hydrothermal vents
2.1.6 understand that the effects of the hydrothermal vent plume can be
detected some distance from the hydrothermal vent site
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modern technology can detect the high temperatures and toxic chemical
composition of the water from many miles away
2.1.7 explain how the chimneys form at hydrothermal vents, including
reference to temperature and solubility of salts
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as water fill of dissolved minerals seeps into the cracks of the crust it gets
superheated but is then expelled and meets the cold water , which will make the
minerals precipitate out of the solution due to lack of solubility forming solids
that pile on each other, this sedimentation forms a chimney at openings
2.2 – Weathering , Erosion ,
Sedimentation
2.2.1 distinguish between weathering and erosion
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weathering – gradual breaking down of substances into smaller pieces
erosion – material is broken down and transported to a new location
2.2.2 describe the three main types of weathering: chemical, physical and
organic, and be able to describe an example of each type
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chemical weathering – chemical composition of rock is changed mostly by oxygen
or water
o rain dissolves ions in rock , often eroding as runoff
physical/mechanical weathering – changes physical not chemical composition
o constant heating and cooling of rocks weaken structure
o water gets in cracks and increase size
o constant wave action against rocks , also chemical weathering
organic/biological weathering – performed by living organisms
o lichens release special compounds that weather rocks
o tree roots growing in rocks cracks , breaking the rock as it widens
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2.2.3 describe the four main types of erosion: by ice, water, wind and
gravity
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ice erosion – ice crushing rock
o glaciers crushing rocks by moving over it and crushing , and continues to
move carrying the sediments at the bottom of the glacier
gravity erosion – the moving of rock through gravitational forces
o rock falls off a cliff into ocean
wind erosion – wind blowing and picking up sediment
o gusts/hurricanes on beaches/desserts
water erosion – water picks up sediment and carries them through runoff
o river in between a canyon weathers rock & deposits them to new location
o can weather and erode at same time
2.2.4 describe sedimentation as the deposition of suspended particles
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sedimentation – the deposition(delivery) of suspended particles(sediments) to a
new location
2.2.5 understand how the speed of water flow and particle size affect the
removal, transport and deposition of particles
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faster the water , the larger particles it can carry
the smaller the particle , the longer it can stay in suspension
2.2.6 define the littoral zone as the intertidal region on a shoreline,
between the highest and lowest spring tide marks
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littoral zone - the area where the land meets the sea between the highest spring
tide and lowest spring tide water marks
2.2.7 state examples of the littoral zone, including rocky shores, sandy
shores, muddy shores, estuaries and deltas
2.2.8 describe how weathering, erosion and sedimentation give rise to the
morphology of rocky shores, sandy shores, muddy shores, estuaries and
deltas
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rocky shores
o made of a rocky substrate
o varies in slope and rock size
o made of granite/igneous rock , resistant to weatherings
o rock gradient : larger rocks are farthest due to wave action
o most exposed , but resistant to erosion
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o limited sedimentation due to wave speed
sandy shores
o made of silica(loose sand deposits) , gravel , and shells
o formed by sandstone erosion and sand sedimentation
o in constant motion by wind and water erosion , moving up and down beach
o gradual slope towards ocean due to wave action
muddy shores
o found in protected regions
o least exposed and most resistant to weathering and erosion
o very shallow or no slope at all
o lack of water movement –-> deposition of fine silt/organic material
o founded primarily by sedimentation
estuaries
o partially enclosed , brackish bodies of water
o sheltered from erosion and weathering of waves
o bottom is made of fine silt fall out of suspension
o highly murky and turbid
deltas
o triangular areas at river mouths where land meets the sea
o river picks up sediments from mouth , and as it widens into tributary
channels , the water slows and sediments fall out of suspension and sink
to the bottom
o these sediments form sandbars
o fan structure resembling a tree
2.3 – Tides and Ocean Currents
2.3.1 explain how tides are produced, and how the alignment of the Earth,
Moon and Sun, coastal geomorphology, wind, air pressure and size of water
body affect the tidal range
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tides – periodic rise and fall of surface of water bodies
diurnal – 1 high and low tide daily
semi – diurnal - 2 high and low tide daily
tidal range/amplitude – difference between coastline’s highest and lowest water
mark due to : *Bay of Fundi , Canada
o gravitational interactions of Sun , Moon , Earth
o physical features of the coastline
▪ narrow channels increase tidal height
▪ open areas decrease tidal height
o environmental factors(size of water body , wind , air pressure
tidal surge – abnormally high coastal flooding from low pressure system
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2.3.2 explain the formation of spring and neap tides
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spring tide – Sun and Moon are aligned with Earth creating the greatest tidal
range since the gravitational pull is all in the same direction , it’s amplified
o creates a larger ocean bulge
o higher tidal range
neap tide – Sun and Moon are perpendicular to Earth , creating the smallest tidal
range since the gravitational pulls are in opposite directions , it’s weakened
o creates a smaller ocean bulge
o lower tidal range
2.3.3 interpret tide tables and graphs in terms of tidal height, tidal
range, spring and neap tides
2.3.4 describe how wind, temperature, density, the Coriolis effect (limited
to the deflection of currents clockwise in the northern hemisphere and
anticlockwise in the southern hemisphere) and the shape of the sea bed
produce ocean currents and upwelling
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currents – continuous , directional movement of seawater
o created by wind , temperature , salinity , desnity , seabed shape , and
Coriolis effect(deflection of currents clockwise in Norther hemisphere and
counterclockwise in the southern hemisphere)
surface currents
o driven by global wind patterns
o caused by Sun’s uneven heating of Earth’s surface
o areas like equator with excess heat energy transfer heat energy until it
sinks to areas with less radiation and cooler temps , forming predictable
winds due to Coriolis effect
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deep currents
o thermohaline circulation – deep water circulator caused by density
differences due to temperature and salinity changes
▪ movements called global ocean conveyer belt
downwelling – downward movement of saltier , denser water
o mixing water column
upwelling – movement of cold , nutrient – rich water from deep ocean to surface
due to wind moving warming surface water away to be replaced by this colder ,
nutrient – rich water
o also caused by topography(mid – ocean ridges deflecting water upwards)
o adds nutrients to surface producers (Acting as fertilizer)
o increasing primary productivity creating healthy , productive ecosystems
2.3.5 explain the formation of the global ocean conveyor belt and its
importance in moving sea water around the Earth
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deep water currents facilitated by thermohaline circulation
essential to our global climate patterns(by bringing warm water to cold
areas/cold water to warm areas ; or water that is not typical of that latitude)
2.3.6 discuss the causes and effects of El Nino and La Nina events during
the El Nino Southern Oscillation (ENSO) cycle in the Pacific Ocean
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normal conditions
o currents flow North along West coast of South America bringing cold ,
nutrient – rich water to equator
o strong southwestern winds blow water away from South American coast
causing upwelling that highly benefits their fishing industries
o Western winds push large amounts of warm water towards Australia and
Asia , bringing storms and rains to these areas
El Nino – caused by Western winds stop blowing in their normal pattern , causing
warm water to buildup on South American coast
o this stop upwelling usual with the Humbolt current
o this reduces primary productivity
o this damages fishing industries and disrupts food webs
o causes drought in Australia and Asia
o leads to increased rainfall in Peru
La Nina – cooling phase after El Nino where stronger than average winds blow
winds off the South American coast allowing for cold water from Humboldt
current to upwell
o decreases sea temperature
o increases hurricane activity in Atlantic Basin
Aarav Reddy