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231 Cards in this Set

  • Front
  • Back
Sea surface currents are controlled by?
3 primary physical mechanisms
These 3 primary physical mechanisms are?
1.) Wind stress
2.) Pressure gradient
3.) The coriolis effect
Wind and the coriolis effect create?
The ekman spiral
An ekman spiral is?
Water moving circularly at a depth of 100-200 m
Coriolis effect effects anything that moves. T or F?
The coriolis effect of the north compared to the south?
North: To the right and clockwise
South: To the left and anticlockwise
Surface currents move...
At 45 degrees to wind direction
With depth, the Coriolis effect...
Continues due to friction with underlying layer, but at a certain depth there will be no motion.
What is ekman transport?
The summed effects of ekman spiral, water moves 90 degrees to direction of wind
The pressure gradient...
Works opposite in ekman transport
Due to ekman transport, water is pushed to?
Center of ocean
A _______ is developed due to gravity.
Pressure gradient
________ flow around the periphery of ocean basin.
Gyres in balance between pressure gradient and coriolis are called?
Geostrophic gyres
Western intensification is due to?
Trade winds and convergence of water in western central gyres, and rotation of Earth.
The rotation of Earth is called?
Western boundary currents...(5)
1.) Narrow
2.) 50 - 75 km
3.) Deep 500 m
4.) Fast 3 - 10 km/hr
5.) Move warm water toward poles
What are some examples of western boundary currents?
Gulf stream, Kuroshio current
Eastern boundary currents...(4)
1.) Wide
2.) Several 1000 km
3.) Slow
4.) Less than 1 km/hr
What are some examples of eastern boundary currents?
Canary current, California current
What are the types of wind-induced vertical circulation? (3)
1.) Equatorial upwelling
2.) Coastal upwelling, downwelling
3.) Langmuir circulation
What is equatorial upwelling?
Currents, because of coriolis, moving away from each other so water has to be filled in, this is where vertical circulation comes in taking water from deep.
Coastal upwelling or downwelling is?
Due to winds parallel to coast in conjunction with coriolis
Langmuir circulation is?
Creates windrows on surface; only about 20 m deep
What is the average depth of the ocean?
3,800 m
Deep ocean circulation is...
termed thermohaline
Why is deep ocean circulation termed thermohaline?
Caused by density differences produced thermal and salinity changes in seawater.
What part of total volume of ocean water is dominated by deep ocean circulation?
90% of total volume of ocean water
What are some general features of thermohaline circulation? (3)
1.) Salinity and temperature become stable when water sinks below contact with atmosphere
2.) Therefore, a parcel of seawater maintains it's temperature and salinity identity (Density) even after 1000 km of travel
3.) Oceans are distinctly stratified with least dense on top and more dense on bottom
All water below a certain depth will be...
Between 1-2 degrees C
Formation of deep waters...
Poleward of 45 degrees, increased evaporation, ice exclusion and cooling make denser water, which will sink to appropriate depth
The formation of deep waters...
Only happens in a few locations
From formation to deep circulation to upwelling...
Takes about 1000 years
The whole process is called?
Oceanic conveyor system
Sediments are?
Particles of organic or inorganic matter that accumulate in unconsolidated form
How are sediments classified?
By source and/or particle size
There are several factors that control the distribution and thickness of sediments within the world's oceans. T or F?
Sediments are important recorders of ___________ and contain __________ ___________.
Earth's history, valuable resources
Classification of sediment by source...
Four marine sediment types may be defined by their source of origin.
These four types of marine sediments are?
1.) Lithogenous (Terrigenous)
2.) Biogenous
3.) Hydrogenous
4.) Cosmogenous
Lithogenous (Terrigenous) sediments...(4)
1.) Originate on land
2.) Weathering and erosion of rocks
3.) Transported to ocean by rivers, wind, or volcanic eruptions
4.) Most abundant sediment type on continental margins (Shelf, slope, rise)
Classification of particle size? (5)
1.) Based on Wentworth scale that comes from logarithmic functions
2.) Gravel - > 2 mm
3.) Sand - .062 - 2mm
4.) Silt - .004 mm - .062 mm
5.) Clay - < .004 (Mud with silt)
Sorting based on size?
1.) The variation in grain size within a sample
2.) Sorting is a function of energy of the environment
Well sorted sediments...
Are all or almost the same size particles, they tend to occur where energy level doesn't vary much (Waves)
Poorly sorted sediments...
A mix of sediment size, a function of variable energy levels (River mouths)
Sediments mature as...(4)
1.) Clay content decreases
2.) Sorting increases
3.) Non-quartz minerals decrease
4.) Rounding of grains increases
Main terrigenous sources are? (4)
1.) River input
2.) Glacier input
3.) Wind input
4.) Volcanic input
What controls river input?
1.) Higher latitudes, arid climates, mostly mechanical weathering
2.) Tropics, high rainfall, chemical weathering (Clay particles)
Glacier input is controlled by?
1.) Glacier outwash
2.) Dropstones
Glacier outwash is?
A significant contributor in high latitudes
Dropstones are? (4)
1.) Deposits carried by icebergs
2.) Important for determining geology of source area
3.) Important paleoclimate reconstruction
4.) Heinrich events
What are Heinrich events?
Layers of dropstones in sediment that indicate huge iceberg armadas in North Atlantic ocean at certain times, it records cycles about Earth
Glacial deposits reach about...
20% of sea floor
Wind input...(5)
1.) Transports only fine materials to deep sea
2.) Significant contribution, 1-2.5 mm/ 1000 years
3.) Varies through geologic time, maybe more during glacial episodes
4.) Glacial-interglacial variability in slope sediment of the Bahamas
5.) Potentially carry viruses, affect corals, affect respiratory health, tied to el nino cycles
Why may there be more wind input during glacial episodes?
Climates are more pressured so winds increase, thus more wind blown particles
What is the African dust story? (3)
1.) The Sahara desert is a huge source for wind blown sediment
2.) The dust from Africa can get to Florida
3.) It was studied how the dust from Africa carrying diseases effect Florida'a coral reefs
Volcanic input? (5)
1.) Deposits fine ash layer, sometimes several cm thick
2.) Common around active margin (Or "Ring of Fire")
3.) Usually one-time event, therefore can be used to correlate across distances in ocean
4.) Tephrochronology
5.) Volcanic input into atmosphere have a effect on global climate (Ex. Mt. Pinatubo)
What is tephrochronology?
Using ash layers to age date marine sediments
What is an example of this tephrochronology?
Santorini volcanic explosion approximately 3,600 years ago, may have brought demise of Minoan civilization, and may be connected to the biblical event of the "parting of the red sea"
Biogenous sediments are?
Sediments of biologic origin; Shells of organisms
What are the two main types of biogenous sediments in the oceans?
1.) Siliceous
2.) Calcareous
Biogenous sediments cover the largest percentage of the sea floor but less total volume than terrigenous. T or F?
The biogenous sediments...
May be from benthic, or planktonic organisms
1.) Live on bottom
2.) Corals - build up large reef masses (Great Barrier reef; also common rock record Permian Basin U.S.A.)
3.) Algae - green calcareous algae; red coral algae
4.) Molluscs
5.) Benthic foraminifera
6.) Sponges - siliceous spicules
7.) Stromatolites
Benthic foraminifera are?
Single celled animal that makes small shell made of CaCO3, often called "salinity indicators" based on shell
1.) Typical of sediments of deep sea, can be significant on slope and rise
2.) Calcareous - coccolithophorids, foraminifera
3.) Siliceous - diatoms, radiolarians
Coccolithophorids and diatoms are...
Single celled plants
Foraminifera and radiolarians are...
Single celled animals
Hydrogenous sediments are?
Formed inorganically from seawater, sometimes called authigenic (Form in place)
Hydrogenous sediments include?
Manganese nodules, phosphates, metal sulfides, non-skeletal carbonates, and evaporates.
Manganese nodules are?
In deep sea and there has to be a low sedimentation rate for them to form
Ooids are?
Spherical grains created from precipitation carbonate in shallow tropical settings (Possibly biomediated; Thompson work)
What are whitings?
Direct precipitation into water column in shallow tropical settings
Cosmogenous sediments are?
Form from outer space
Cosmogenous sediments include...
Meteorite impacts and cosmic dust (Earth is bombarded with this all the time)
What is thought to form from meteorite impacts?
Microtektites which are small glassy particles
When was there a large impact?
65 million years ago, which was 10 km in diameter and created mass extinctions, it also created the Chicxulub crater
The distribution of marine sediment includes?
1.) Neritic sediments
2.) Pelagic sediment
Neritic sediments are?
Sediments that occur on the continental shelf, it is mostly terrigenous
Pelagic sediments are?
Sediments that occur on continental slope, rise, and deep ocean basins, it is mostly biogenous
Pelagic clays...
Sediment from wind, usually settle very far away from source, deep ocean
How are areas classified?
By the dominant sediment type
Continental margin sediments...(4)
1.) Depositional rates vary; estuaries may trap sediment
2.) More terrigenous than biogenous, but high productivity
3.) Grain size coarser near continent, finer further from shore (Function of energy)
4.) As thickness of sediments increases lithification may occur
Why are some coarse grain sediments near the shelf edge?
Sea level was lower so that was where the shore was
Background of deep sea sediments? (3)
1.) HMS Challenger was first systematic study of deep sea sediments
2.) John Murray used the terms ooze and clay
3.) 1872-1876 first time study of ocean sediments
What are some general patterns of deep sea sediments? (3)
1.) Mostly depth-controlled (Related to the CCD)
2.) Siliceous deposits accumulate beneath high productivity areas
3.) 1/2 of sea floor is covered by oozes
Deep sea sediments may include?
All four sediment types (Terrigenous, biogenous, hydrogenous, and cosmogenous)
What accounts for the types of sediment deposited for deep sea sediment?
Low sedimentation rates, process of elimination accounts for types of deposit
For deep sea sediments, depending on composition, different sediments include? (3)
1.) Turbidites
2.) Oozes
3.) Clays (Clays that blow off continent)
Turbidites? (4)
1.) From turbidity currents
2.) Combination of terrigenous and biogenic
3.) Movement of shallow sediments to deep sea
4.) Characteristic graded bedding of sediments (Bouma sequence)
Biogenic oozes?
1.) Composition and distribution controlled by productivity and preservation
2.) Most shells dissolve before they reach the sea floor or at the sea floor
CaCO3 shells...
Don't dissolve in surface waters but start to dissolve once they reach a certain depth of the ocean. Siliceous shells are opposite.
What is pelagic rain?
Sediment that falls to the sea floor, making a flurry like snow.
How long does it take particles (Shells, pelagic red clay) to reach the sea floor? (4)
1.) Sediment traps indicate that much is incorporated into fecal matter
2.) Otherwise it may take years for fine particles to make sea floor
3.) Forams and radiolarians take a couple of weeks
4.) "Aggregates" also important (Masses of something)
1.) Deep sea sediment containing more than 30% biogenous material
2.) 1-4 cm/1000 years
Oozes are named...
After dominant remnant organism
The types of oozes are?
Siliceous and calcareous
A calcereous ooze may be made up of?
Mat be foraminfera, pteropod or coccolithophorid ooze
What is a pteropod?
A little mollusc with a shell
A calcarerous ooze...
1.) Shells and tests accumulate on sea floor
2.) Below certain depth CaCO3 dissolves (~4.5 km depending on ocean)
The depth that CaCO3 dissolves is?
The depth is the Calcite Compensation Depth (CDD), it is the boundary line of CaCO3
Calcareous oozes and the CCD?
1.) Surface waters are supersaturated with respect to calcite
2.) Deep water are undersaturated with CaCO3
What is the CCD in respect to the Atlantic and Pacific?
1.) CCD in the Atlantic is about 5 km
2.) CCD in the Pacific is about 4 km
Why is there a difference in the CCD from Atlantic to Pacific?
The Pacific ocean has more CO2 so the depth is shallower because the CO2 is more corrosive breaking the CaCO3 faster and easier
What exactly is the CCD?
Calcite Compensation Depth - the depth on the ocean floor where rate of supply of calcium carbonate sediments equal the rate of dissolution, therefore no accumulation.
The CCD is also called?
The "snowline," white calcium carbonate then brownish sediment, clay sediment
What controls the depth of the CCD?
1.) Cold water, more dissolution
2.) High pressure, more dissolution
3.) The most important factor is the amount of CO2 in the water
The CO2 in the water...
Is effected by respiration and photosynthesis
What is the equation for the effect of CO2 on the CCD?
CO2 + H2O + CaCO3 --> Ca2+ + 2HCO3-
The effect of CO2 on the CCD is also called?
Thermohaline circulation
What is the hysocline?
The depth on the seafloor where there is a marked shift in dissolution rate (Usually maximum dissolution rate) and a change from good preservation to poor preservation of assemblages
The hysocline...
1.) Delicate and robust shells fall evenly but after a certain point delicate ones disappear
2.) Hysocline roughly follows calcite saturation level in water column
1.) Occur where there is lack of other sediments deeper than CCD
2.) Slow accumulation (<2 mm/1000 years)
3.) Mostly brown or reddish (Often called red clays)
What is stratigraphy?
Study of layered sedimentary deposits
What is paleoceanography?
Study of the oceans history
Stratigraph and paleoceanography?
Originally believed that deep sea contained sedimentary record of all that occurred in oceans
Why is this theory wrong?
The sea floor is continually spreading and crust is being recycled
Sediments and climate history? (3)
1.) Changes in abundance of siliceous/calcareous ooze tells about productivity and CCD
2.) Temperature sensitive microfossils tell about current and climate change
3.) Geochemistry of shells and tests such as: Oxygen isotopes tell us about ice ages and sea level. Carbon isotopes tell us about past productivity CO2 fluxes
Waves are?
Energy along the interface between ocean and atmosphere
Waves derive their energy from?
Energy and motion from wind
What are the parts?
Crest and trough
Measurements of a wave?
1.) Wave height
2.) Wavelength
3.) Wave period
Wave height?
H, the distance between a trough and a crest
L, the horizontal distance between successive crests (Or troughs)
Wave period?
I, the time interval for one full wave to pass a fixed position
Below the negligible water movement...
Sediments don't move
Wave height, wavelength, wave period depend on? (3)
1.) Wind speed
2.) Length of time the wind blows
3.) Fetch
What is the fetch?
The distance that the wind travels
As a wave travels...
The water passes energy along by moving in a circle
As a wave moves...(3)
1.) Waveforms moves forward
2.) Energy, not water particles, travel across sea surface
3.) At a certain depth of about one-half the wavelength, the movement of water particles becomes negligible
The movement of a wave becomes negligible at?
The wave base
When waves approach the shore...(3)
1.) Waves begin to "feel" the bottom as they approach shore (less than 5m)
2.) Waves slow (Shallow water) but following waves catch up therefore wavelength decreases as height increases
3.) 1/7 ratio they become to steep and they break
What is the zone where the waves break called?
Surf zone
Energy of a wave is...
Expelled on beach or reflected
Wave erosion is caused by?
Wave impact and pressure
Wave erosion...
Breaks down rock material and supplies sand to beaches
What is abrasion?
Sawing and grinding acting of water armed with rock fragments
The more energy there is with waves...
The larger particles there will be on beach
What is wave refraction?
Bending of a wave and arrives parallel to shore
The results of wave refraction are?
1.) Wave energy is concentrated against the side and ends of headland
2.) Wave erosion straightens an irregular shoreline
As waves break down headlands...
Tectonic processes create more rocky headlands
What is longshore transport?
Known as beach drift, sediment moves in a zigzag pattern along beach face
The longshore current...(3)
1.) Is the current in the surf zone
2.) Flows parallel to shore
3.) Moves substantially more sediment then beach drift
The only thing constant on a beach is?
1.) Shore normal and shore is parallel to wave movement
2.) Erosion occurs when output is greater than input
3.) Accretion occurs when input is greater than output
What is the offshore zone?
Part of beach that is deeper than wave base
From offshore to mean low tide
From low tide to berm
Above high tide
Longshore bar?
Sand bar below low tide
Built up by wave action in foreshore
Sand resource in backshore
What is a sediment budget?
Estimate sources and losses for a beach
What are the sources for a beach? (4)
1.) Rivers
2.) Sea-cliff erosion
3.) Longshore (Littoral) movement
4.) Onshore transport
What are some losses for a beach? (3)
1.) Longshore movement
2.) Offshore transport
3.) Wind transport
Both sources and losses are...
Heavily influenced by man
What are beach profiles?
Measurement technique to see change over time on a beach
What is important to remember for beach profiling?
1.) Must understand sediment dynamics
2.) Beach naturally changes
Summer beach profile? (3)
1.) Low flat swell for days
2.) Builds upwardly concave beach with broad berm
3.) Sediment moves onshore
Winter beach profile? (5)
1.) Waves attack the beach
2.) Diminish size of berm
3.) Flatten beach face
4.) Eroded sand moves to longshore bar
5.) Grain size increases
What are barrier islands?
Detached systems of islands separated by inlets (Usually have peat (Organic rich sediment) under it)
Ex.) Atlantic and Gulf Coast
Occurrence of barrier islands?
Need an abundant supply of sand and gentle sloping shelf
Barrier island environments are...
Made up of several distinct depositional environments
These barrier island depositional environments are? (7)
1.) Nearshore
2.) Beach
3.) Dune field
4.) Back island flat
5.) Salt marsh/Mangroves
6.) Lagoon
7.) Mainland
Back island flat...(5)
1.) Made up of sand blown from dunes
2.) Washover fans
3.) May or may not be vegetated (Or developed)
4.) Bounded (Or behind it) by salt marsh (Or mangroves)
5.) Sand sink (Lost to back)
Barrier island origin is...
Derived from three theories
What are these three theories of barrier island origin?
1.) Submerged of a coastal sand ridge
2.) Detached spit
3.) Vertical growth (Accretion) of longshore bar
What is a spit?
Elongation of sediment from mainland
Barrier islands are...
Huge sand repository
Barrier islands...
1.) Move inward with sea level rise
2.) Therefore lagoon deposits may be overlain by beach sand
What might prevent a barrier islands landward migration?
Tidal inlets...(3)
1.) Flush the bay during outgoing tides
2.) Change position frequently in combination with sediment movements
3.) Often open during storm events
What are some coastal modifications to help prevent beach loss? (5)
1.) Groins
2.) Jetties
3.) Break water
4.) Sea walls
5.) Beach nourishment
What are groins?
Perpendicular structure to shore designed to catch longshore sediment
What are jetties?
Perpendicular to shore at mouth of inlets
Break waters are?
Built parallel to shore to knock down wave energy (Offshore)
Sea walls are?
Parallel to shore, built to stabilize sediment, built right on beach to try to stop wave energy
What is beach nourishment?
Sand lost from beach is then retrieved and put back on beach
What are the examples of hard stabilization?
Groins, jetties, break waters, and sea walls
What are the samples of soft stabilization?
Beach nourishment
What are the features of a rocky coast? (7)
1.) Wave-cut platform
2.) Sea cliffs
3.) Sea caves
4.) Sea arches
5.) Sea stacks
6.) Blow holes
7.) Tombolo
Wave-cut platform?
Flat rocky platform from abrasion
Sea cliffs?
High, rocky coasts that plunge down to the sea's edge
Sea caves?
Type of cave formed primarily by the wave action of the sea
Sea arches?
Arch shape feature on coastline
Sea stacks?
Collapsed sea arch
Blow holes?
Water comes into cave and shoots out of top
Sea stack connected to beach with sand spit
Rocky coasts are common...
On active margins
A tower carst feature is?
A structure made of limestone that is like a sea stack but is not near the coastline
Erosional coast processes?
1.) Initially an irregular shoreline may develop, but the long term processes tend to straighten the shore
2.) Wave refraction tends to focus waves energy at headlands and allows deposition in embayments
What is episodic erosion?
Erosion that happens in spurts
Episodic erosion? (7)
1.) One storm rarely produces noticeable change
2.) Vulnerable at base
3.) Chemical and mechanical weathering may occur
4.) Undercutting, oversteeping, and collapse (Of cliffs)
5.) Base protected by fallen debris until waves clear energy
6.) Cycle starts over
7.) Episodic
Deltas? (4)
1.) From the Greek letter, based on the shape of the Nile River delta
2.) Occur when river supplies a large enough amount of sediment
3.) Empties directly to sea
4.) Forms if sediment supply is greater than erosion by waves and tides
What is delta physiography?
The physical geography or parts of a delta
What are the parts of the delta physiology?
1.) Delta plain
2.) Delta front
3.) Prodelta
Delta plain? (3)
1.) Flat lowland above sea level, active and abandoned distributary channels (Sands)
2.) Interdistributary vegetated or flooded (Muds)
3.) Topset beds
What are topset beds?
Flat beds of sediment deposited
Delta front? (3)
1.) Shoreline and broad submerged portion of delta
2.) Slopes gently seaward
3.) Sandy muds
What are sandy muds?
Fine grained sediments with some sand particles
Prodelta? (2)
1.) Deep, most seaward muds
2.) Bottomset beds, settle from suspension
Delta types are...
A function of waves, tides, sediment supply
What is a river-dominated delta?
"Birds foot delta," sediments coming down river not really dependent on waves or tides, deposits lobes of sediment
River-dominated delta?
1.) Waves and tides have little influence
2.) Sediments deposited at river mouth
Ex.) Mississippi River delta
What is a wave-dominated delta?
Sediment flattened out along coastline
Wave-dominated delta?
1.) High wave energy
2.) Dispersal of sediment away from mouth of river
Ex.) Rhone River in the North Sea
What is a tide-dominated delta?
1.) Tidal currents rework sediment into long linear bars
2.) Fan out at mouth of river
Ex.) Brahmaputra in Bangladesh
What is an estuary?
Semi-enclosed body of water with inflow of both salt and fresh water (Contrast with lagoon which is just salt), "estuary" from latin aestuarium which means tidal
What is the importance of estuaries? (3)
1.) Natural navigable harbor
2.) Buffer zone between marine and freshwater environment, import biologically (Marine fish have larval stage in estuaries)
3.) Heavily impacted by humans
What are the three parts of estuaries?
1.) Head
2.) Main estuary
3.) Mouth
What is a head of an estuary?
Where river enters estuary
Ex.) Hillsborough Bay
What is a mouth of an estuary?
Seaward end of estuary
Ex.) Egmont Key
Based on the origin and evolution, estuaries are?
Origin and evolution of estuaries?
1.) Formed during last sea level rise
2.) Generally short-lived (Geologically)
Why are estuaries usually short lived? (3)
1.) Get filled-in
2.) River sediment input
3.) Import of sand and mud from offshore
The degree of infilling...
Is a function of sea level change and sedimentation rate
What are the four types of estuaries?
1.) Drowned river valley (Coastal plain estuary)
2.) Fjord, glacially carved valley that is drowned
3.) Bar-built estuary
4.) Tectonic estuary
Fjord, glacially carved valley that is drowned...
1.) Often have glacial moraine out mouth (Sill)
2.) May create anoxic conditions in deep fjord due to lack of circulation
What are moraines?
Small little hills of sediment deposits left behind from a glacier
What is a bar-built estuary?
Created by barrier at estuary mouth
What is a tectonic estuary?
Created due to subsidence along fault, Ex.) Tomales Bay, San Francisco
What is the fifth type of estuary that is a rarity and what makes up Tampa Bay?
Carst-controlled estuary
What is a carst-controlled estuary?
Created by sinkholes
How are estuaries classified?
Based on physical characteristics (Circulation), these controlled by freshwater inputs, tides, and winds
What are the classification of estuaries? (3)
1.) Salt-wedge estuaries (Stratified estuaries)
2.) Fully-mixed estuaries
3.) Partially-mixed estuary
What is a salt-wedge estuary?
1.) River-dominated, weak marine inflow due to small tide
2.) Vertical salinity stratification salt below, fresh above
What are fully-mixed estuaries? (4)
1.) Tide-dominated
2.) Well-mixed, vertically homologous OR
3.) Lateral salinity gradient, incoming saltwater, outgoing fresh
4.) Generally wider than .5 km
What is a partially mixed estuary?
1.) Characteristic of both salt-wedge and fully-mixed estuaries
2.) Vertical salinity gradient, salt - brackish - fresh
Estuary circulation?
Is due to the coriolis effect and estuaries circulation
Counterclockwise circulation in the northern hemisphere, why?
Currents keep trying to go right so the circulation will lead going counterclockwise
Estuary circulation...
May effect sediments, marine sediment on one side, and river sediment on the other side