Eaos weekly quizes Flashcards
Because the earth is a closed system
The mineral resources on this planet are all we have and - for the foreseeable future - all we will ever have
When vegetation washes off the landscape and settles to the floor of a Fiordland fjord carbon is transferred from the ______ to the _______
Biosphere; Geosphere
When westerly winds blow over the southern ocean, energy is transferred from the ______ to the ______
Atmosphere; hydrosphere
The situation where material has a very long residence time in a reservoir is called
Sequestration
Sedimentary rocks provide clues about
- Geologic activity at the time of deposition
- Past climates
- Surface conditions at the time of deposition
What rock type results from lithification of magma/lava
Igneous rock
What rock type results from heat and pressure
Metamorphic rock
Observations that developed into the principle of uniformitarianism led scientists to conclude that earth must be much ______ than previously thought
Older
What are geological unconformities
- They are contact surfaces between rocks of very different ages
- They represent gaps in the continuity of the geologic record
- They can form through erosion or non-deposition
You will find fossil remains in what type of rock
Sedimentary rock
What is the origin of the element hydrogen in the universe?
The big bang
What is the origin of the element oxygen in the universe?
Nuclear fusion in stars
The color of a star is mainly an indication of its
Temperature
Planets within a stars habitable zone
Receive an amount of solar energy appropriate for liquid water to be present
How did earth get its water
Accretion of meteors
What is the principle evidence for oceans having been present on earths surface throughout most of its history
Marine sedimentary rocks
In addition to earth being within the suns habitable zone, what additional factors have allowed this to be the case
- Earths composition
- Earths magnetic field
- Earths mass
How is Mars currently in ice house climate
- Uv radiation splits atmospheric H2O into H2 and O2 due to weak magnetic field
- Both these can escape easily due to weak gravitational field
- O2 also consumed by oxidization of Iron on surface, hence mars red color
- H2O frozen in the polar ice caps and beneath the surface
What factors have made it difficult for liquid water to be present on the surface of Venus for most of its history
- Venus distance from the sun
- Runaway greenhouse
- Weak magnetic field
Why does the oceanic lithosphere of the pacific plate subduct beneath continental lithosphere of the Australian plate at the Hikurangi convergent plate boundary in the eastern North island of New Zealand
The oceanic lithosphere (pacific plate) is denser than the continental lithosphere (Australian plate) it subducts beneath
What causes mid-ocean ridges to rise high above the surrounding seafloor
Upwelling of hot, buoyant asthenosphere under mid-ocean ridges
Plate motion relative to mid-ocean ridge equation
Kilometres/millions of years = millimetres per year
What kind of plate boundaries occur at mid-ocean ridges
Divergent and Transform plate boundaries
How does paleomagnetism support the theory of plate tectonics
It reveals marine magnetic anomalies which result from seafloor spreading
Evidence used in Alfred Wegener’s continental drift hypothesis
- Fit of the continents
- Locations of past glaciations
- Paleoclimate evidence
- Fossil distribution
- Matching geological units on separate continents
Exposures of Haast schist often show planar cracks that form when overlying rock is removed by erosion. The removal of overburden reduces the pressure acting on the rock, allowing it to expand and crack. What type of weathering mechanism does this process describe
Jointing
When limestone undergoes chemical weathering to produce Ca2+ and 2HCO3-, what type of reaction is occuring
Dissolution
When igneous rocks undergo chemical weathering to produce Kaolinite clay, what type of reaction is occuring
Hydrolysis
Which mineral is most stable at earths surface and weathers slowest
Quartz
True or false: soil forms when rates of erosion are greater than rates of weathering
False
True or False: In biogeochemical cycling, generally the larger the reservoir size (i.e concentration of the element in the reservoir), the slower the flux of the element in/out of the reservoir
True
What sort of timescales do carbon reservoirs in the deep ocean operate on
100 to 1000 years
What are the three main processes that control the removal of CO2 from the atmosphere into long-term sinks
- Chemical weathering of silicate rocks
- Burial of organic matter
- Burial of calcareous rocks
What does the term “stream discharge” refer to
The volume of water flowing past a certain point in the stream per unit of time, typically measured in cubic meters per second (m3/s)
Lateral accretion surfaces in meandering rivers are formed by:
The deposition of sediments on the inner bends of meanders, contributing to point bar growth
What best describes a braided river channel
Multiple channels that intertwine, seperated by temporary sediment deposits known as bars
Helicoidal flow in a meandering river refers to
A corkscrew-like, spiral movement of water from the river bottom to the surface and along the meander bend
If the cross-sectional area of a stream channel is 10 square meters (m2) and the average velocity of water flow is 2 meters per second (m/s), what is the streams discharge
20 m3/s
A hydrograph of a small, urban catchment area shows a rapid rise to peak discharge following a rainfall event, compared to a hydrograph from a large, forested catchment. What is the most likely explanation for this difference
The impermeable surfaces in urban areas increase surface runoff, leading to faster peak discharge
What is stream capture
The process by which one stream erodes the land separating it from another stream, eventually diverting the flow of the captured stream
What characterises an antecedent stream
A stream that has maintained its original course and valley while the surrounding landscape has been uplifted
Which sedimentary particles are most easily transported by water
Clay
Which sedimentary particles are most easily eroded by water
Sand
Marine sediments are generally thickest on the
Continental slope
Marine sediments are generally thinnest on the
mid-ocean ridges
Using understanding of longshore drift, predict the general direction of sediment migration along the Otago coastline
From southwest to northeast
Pelagic sediments are dominated by
Clay particles and the microscopic remains of phytoplankton and zooplankton
Which acoustic tool would you use if you wanted to seismically image up to 200 meters below seafloor
Boomer
Why is the vertical axis of a seismic image usually in time (ie how long it takes sound to travel from the surface to the reflector and back again) rather than depth
The velocity of sound changes depending on the medium it is travelling through
What is the velocity of sound in water
1500 m/s
Why might you want to preserve the configuration of seafloor sediments just below the sediment-water interface
A record of change in properties with time can be constructed with undisturbed sediments
If all of the ice in Antarctica were to melt, sea level would rise by
About 60 m
Sea ice is
Ice that forms by freezing of surface ocean water
The maximum velocities of ice of the Antarctic ice sheet are
Around 1000 to 4000 metres per year
True or false: Sea ice extent has declined significantly over the last three decades in the arctic but remained stable in the antarctic, with new signs of decline over the last 3 years
True
The major effect of recent climate change on the antarctic ice sheet is
Warmer ocean waters are causing thinning of ice shelves increasing the driving force for ice flow
Ice core paleoclimate records are unique in providing
Past atmospheric gas compositions from bubbles trapped in the ice
There are than __ types (phases of H20 ice
10
How much of the earths water is in the form of freshwater
2.8%
True of false: The density of ice is much greater than that of water
False
Water facts and principles
- Water bonds with itself, so it has surface tension and capillarity
- Water has high heat capacity, which means it can absorb a lot of heat
- Water is very reactive so it dissolves more substance than any other fluid
- Water is essential for life on earth
The density of freshwater is
1.0 grams per cubic centimetre
Whan you add salt to water, it becomes
Denser
The ph of freshwater is about: The ph of seawater is about:
Fresh - 7.0
Salt - 8.0
The speed of sound in dry air is:
The speed of sound in saltwater is:
Dry air - 343 m/s
Saltwater - 1500 m/s
Where is the photic zone
Near the surface of the ocean
What is a transect
A line along which you make regular measurements
What is a depth profile
Something measured from the top to the bottom of the water column
“Correlation does not imply causation” means that
If two parameters vary together, they still might not be related
What has a ph of around 12
Soapy water
What has a ph of around 5
Coffee
Nz has some of the highest summer UV levels in the world due to
- Earths elliptical orbit means it is closer to the sun in the New Zealand summer months of December and January
- New Zealands relatively clean air means UV radiation is less likely to be scattered by airbourne-pollution and more UV radiation reaches the ground
- The ozone layer over New Zealand is thinner and absorbs less UV radiation
What accurately describes the global pattern of atmospheric circulation on earth if it was rotating
There are three atmospheric circulation cells in each hemisphere
The coriolis effect cause moving air and water to turn which direction in the Northern Hemisphere
Toward the right from the direction of travel
Atmospheric circulation statements
- There are three major cells of circulating air in each hemisphere
- The winds at the base of the Hadley cell are called the trade winds
- Warm, moist air rises in the intertropical convergence zone
What is Ekman transport
The net movement of water at a 90 degree angle from the wind direction
What describes the large scale movement of water in the worlds oceans primarily driven by the major surface wind systems
Gyres
The pressure gradient force causes moving air and water to move in which direction in the Northern hemisphere
Straight line from high to low pressure
What wind direction would cause coastal upwelling along the west coast of the south island, New Zealand
Southwest wind
Equatorial upwelling statements
- Equatorial upwelling occurs due to divergence of Ekman transport at the equator
- Equatorial upwelling brings nutrient-rich cold water to the surface, promoting high biological productivity
- Equatorial upwelling lifts the thermocline closer to the sea surface
How many subtropical gyres are there in the worlds oceans
Five
Currents in gyres
- Western boundary current
- California current
- Gulf stream
What phenomenon describes the periodic warming of sea surface temperatures in the central and eastern pacific ocean
El Nino
El nino statements
- The trade winds weaken during El Nino
- Water in the eastern pacific is warmer during El Nino
- The thermocline is shallower is shallower in the eastern pacific during an El Nino
La Nina statements
- The trade winds strengthen during La Nina
- Water in the western Pacific is warmer during a La Nina
- Coastal and equatorial upwelling are stronger during a La Nina
Which factors contribute toward deep water production
- Heat loss from the ocean
- Evaporation
- High wind speeds
True or false: For deep water waves, the crest speed is proportional to wavelength
True
Shallow water wave statements
- The crest speed is proportional to water depth
- The crest speed is equal to wavelength divided by wave period
- The crest speed decreases moving into shallower water
Wave dispersion statements
- Wave dispersion affects deep water waves
- The longer wavelength waves move faster than those with a shorter wavelength
- Over time waves with mixed wavelengths separate into groups with similar wavelength
Tsunamis behave as
Shallow water waves
Semi diurnal tide statements
- They feature two high tides and two low tides every 24 hrs 50 mins
- They are generated by forces due to Earths inertia and the moons gravity
- They are due to earths rotation beneath the tidal bulges
Neap tides
Tides that occur when the moon and the soon are aligned at 90 degrees relative to the earth
Nitrogen fixation is carried out by
Cyanobacteria
HNLC regions are symptomatic of iron limitation, but what does HNLC stand for
High nutrient low chlorophyll
How much carbon does the ocean contain relative to the atmosphere
60 x
Ocean CO2 statements
- The ocean is a net sink for atmospheric CO2
- The ocean is a source of atmospheric CO2 in some regions and a sink in other regions
- The net exchange of CO2 between ocean and atmosphere is less than 1% of the ocean carbon pool
Greenhouse gases
- Carbon dioxide
- Methane
- Nitrous oxide
Current average ph of the surface ocean
8.1
Liebigs law says that growth is determined not by the total nutrients available but by
The most scarce
Characteristics of oligotrophic surface ocean
- Low macronutrients
- Low phytoplankton biomass
- Nitrogen fixation
Macronutrients in the ocean
- Nitrate
- Phosphate
- Silicate
HNLC regions account for approximately how much of the global surface ocean
30%
Biogenic sediments
Limestone and chert
Earths early oceans of the archean were
- Rich in iron
- Devoid of oxygen
- Overlain by an atmosphere rich in greenhouse gases
What type of paleoceanographic information does the Mg/Ca proxy provide
Sea surface temperature variations
Paleoceanographic proxy description
A measurable property of a sedimentary archive that responds to changes in the marine environment in predictable ways
What characterised the PETM (paleocene-eocene thermal maximum)
Intense global warming
Aluminum as a normalizing element for proxies using element ratios
- Aluminium has a constant ratio with other elements in common ‘aluminosilicate minerals’ of the upper continental crust
- ‘Al normalisation’ allows the degree of enrichment from non-lithogenic sources to be assessed
- Aluminium is a lithogenic element
Which sediment archive only forms slowly on million year timescales
Ferromanganese crusts
Where does oxygen isotope ‘fractionation’ occur
In both seawater due to the expansion and contraction of icesheets at the poles
When did the oceans become fully oxygenated
During the second great oxidation event
What best describes the Quaternary oceans and climate
The Quaternary period has permanent ice sheets in both the northern hemisphere and antarctica
The Anthropocene has been suggested as the name of the most recent geological epoch because
The widespread geological effects of humanity are now identifiable in most present-day geological settings
Earliest evidence of human activities preserved globally in the sedimentary record
Carbon
Why is copper mining likely to be important for the worlds future energy needs
We will need a lot more of it for transmitting electricity
Which country currently refines most of the worlds rare earth elements, which are used for communication and electronic technology
China
How can lightweight aluminium be produced in a more energy efficient way
Using renewable electricity to power the smelters rather than more traditional methods of refining it
From which geological setting is much of the worlds lithium currently being produced
Ancient evaporated lake beds
What is a external forcing on climate change
Solar radiation
A ‘climate proxy’ can be best defined as
A measurable archive property that responds in a clear and predictable way to a particular climate variable
Isotopes of what element, measured in ice core air bubbles, can be used as a proxy for past global air temperatures on earth
Oxygen
Which of the following is most similar to the human population of earth at the end of the last glacial period (during the early Holocene)
Similar to the population of New Zealand today
