Earth science yr 11 exam info Flashcards
Differentiation
Earths a differentiated planet (composed of layers according to density, more dense near centre and less dense near surface
Seismic waves
Used to learn about earth’s interior, travel through interior during earthquake
speed and direction of seismic waves reveals different layers of earth
Seismic waves
Two types, body and surface, body waves are split into p-waves and s-waves
P-waves
Primary waves
compressional
Travel through solids and liquids
S-waves
Secondary waves
Shear or Transverse
Travel through solids only
Earths layers
2 different type sof layers of the earth; chemical compositon and physical properties
Chemical compositon
Crust, Mantle, Core
Physical properties
Lithosphere Asthenosphere Mesosphere
Core
Crust
Hard, rigid, thinnest layer,
Mantle
Two regions; upper and lower, densel layer of hot semisolid rock(below crust)
Outer core
Only liquid layer-mostly iron and nickel
Inner core
Extremely hot, solid
Earths energy
Earths layers get hotter and more dense towards the centre of the planet.
energy providing this heat is gravity, friction collisions, nuclear fission and decay of radioisotopes
Oceanic crust
layer 1: loose sediment
layer 2: sedimentry rock
layer 3 : basalt
oldest oceanic crust is 200 millions years old, average thickness of 5-8km
Continental crust
Granite is most abundant rock type found in continental crust,
oldest rocks found on this crust (3,900 million years old)
average thickness 45km
Igneous rock
Formed when magma cools, makes crystals.
magma-hot liquid of melted crystals. minerals form crystals when cooled.
can form underground where magma cools slowly, or above where magma cools quickly
e.g. obsidian, basalt, granite
Weathering
Processes at or near Earth’s surface that cause rocks and minerals to break down – in the same place
Erosion
Process of removing Earth materials from their original sites to another location through transport.
can be carried out through wind, moving water, gravity (rock fall) and ice.
Physical weathering
Physical action which breaks up rocks. e.g. frost wedging
Chemical weathering
When the rock is attacked by chemicals. e.g. dissolution
Biological weathering
Occurs when rocks are weakened and broken down by animals and plants. e.g. tree roots
Sediment
Material, originally suspended in a liquid, (settles at bottom when left for long time)
Material eroded from preexisting rocks (transported by water, wind, or ice and deposited elsewhere)
Compaction
Sediment piles causes mass pressure-compaction of sediment
squeezes together resulting in reduction of pore space & sticking together of the grains.
Cementation
Most sediments deposit in water of dissolved minerals.
water flows through pores between sediment grains (some minerals precipitate)
Over time, these minerals effectively glue the sediment together into sedimentary rock
Sedimentary rock
Form at/near earths surface at low temperatures & pressures primarily by sediment deposition by water, wind or ice, precipitation from solution, growth in position by organic processes.
e.g. cola, sandstone, limestone
Subduction
Under heat and pressure, the oceanic plate (thinner, less dense) slides beneath the continental plate (thicker, more dense)
Heat and pressure
Pressure comes from weight of surrounding rocks on all sides.
pressure/heat rearranges structure of rock minerals (no chemical composition change)- forms new minerals and rocks
Metamorphic rocks result from underground pressure and heat from magma/heated water.
Uplifting
Occures through orogeny and volcanic process, which brings rocks to the surface. The rock eventually becomes recycled again.
Metamorphic rock
Formed through intense heat and pressure in earths crust. e.g. marble, slate, gneiss
Melting
Result of continued heating, production of magma, new igneous rocks(cooled magma). process depends on size of reservoir that it drains & intensity/activity of tectonic plates
Crystallization
As magma cools, the melted minerals crystallize, forming an inter-grown mass of crystals – an igneous rock.
The longer it takes to cool, the bigger the crystals, the shorter, the smaller
Intrusive igneous rocks
Forms when magma cools under the surface of the crust. They “intrude” through the crust.
Extrusive igneous rocks
Forms when magma cools on the surface of the crust – it exits the crust.
Felsic rocks
Light coloured - composed of Feldspars and Quartz (which is Silica Oxide) . High in Silica – Greater than 65% by weight.
coarse grained.
e.g. Granite
Mafic rocks
Dark coloured - composed of amphibole, pyroxene and olivine - high in Magnesium and Ferric (Iron). Low in Silica – Lower than 55% by weight.
fine grained rocks
e.g. basalt
Explosive eruptions
High silica content (viscous lava (composite/cinder volcanoes)
Non-explosive eruptions
Low silica content (runny lava) – (Shield volcano)
Composite volcanoes
Formed from ash and lava layers stacked up into steep mountains.
Found along subduction zones
Forms felsic rocks
Generally lower temperatures
Cinder/Tephra cones (Volcanoes)
Created from high eruptions of lava-creating cinder/ash falling into cone shaped hill
Smallest type of volcano
Formed from basaltic lava, can form from andesitic or rhyolitic lava
Shield volcanoes
Gently-sloping volcanoes comprised of basaltic lava (very fluid lava) flows in long-lasting, gentle eruptions - minimal explosions.
Found at hot-spots and along divergent boundaries
Low silica lava allows gas to escape
Higher temperature lava
Lithosphere
Comprises the rigid, outermost layer of the earth. crust and uppermost part of the mantle.
100 km-thick surface of the earth, rigid and brittle, fractures produce earthquakes
Asthenosphere
Hotter upper mantle below Lithospheric plate
flows like silly putty
Viscoelastic solid-not liquid
plates move about on the Asthenosphere
Pangaea
German meteorologist, Alfred Wegener thought that present continents were part of a super continent called Pangaea
Divergent boundaries
When two plates are moving away from each other.
creates mid ocean ridges/continental rift valleys
Transform boundaries
When two plates are moving past one another
the pressure is released as earthquakes (e.g. San Andreas fault)
Convergent boundaries
When two plates are moving towards each other.
three types:
oceanic/continental
oceanic/oceanic
continental/continental
deep oceanic trench forms along a subduction zone.
Plates tectonic driving force
Pull of sinking lithospheric plate (slab) at subduction zones: SLAB PULL.
Push of intrusion, gravity at mid-oceanic ridges: RIDGE PUSH.
Traction caused by motion of asthenosphere below plate: BASAL TRACTION
Principle of Uniformitarianism
The Earth’s geologic processes acted in the same manner and with essentially the same intensity in the past as they do in the present and that such uniformity is sufficient to account for all geologic change.
principle of Superposition
In any undeformed sequence of sedimentary rocks, each bed is younger than the one below it and older than the one above it
This is the basis of relative ages of all strata and their contained fossils
Principle of Original Lateral Continuity
Strata originally extended in all directions until they thinned to zero at their edges of deposition
Thus, matching strata on opposite sides of a valley can be correlated
Principle of intrusive relationships
Invading igneous rock is always younger than the rock it intrudes
This is an indicator of relative age
Principle of cross-cutting relationships
Faults are younger than the rocks they cut
If a fault is found that penetrates some formations but not those on top of it, then the formations that are cut are older than the fault, and the ones that are not cut must be younger than the fault
Uncomformities
Represent major gaps of time
They are the result of periods of erosion or non-deposition
They help us to understand the great age of the Earth
There are three types – Disconformities, Nonconformities
Angular Unconformities
Disconformities
An erosion surface within a sequence of flat-lying sedimentary rocks
Nonconformity
Recognised by sedimentary rocks resting on an eroded surface of igneous or metamorphic rocks
Angular unconformity
Recognised by tilted or deformed sedimentary rocks below flat-lying sedimentary rocks
Biogeochemical cycling- phosphorus
Mineral nutrient (origin in rock and soil)
Limiting in a number of ecosystems
Inorganic (PO43-) and organic phosphate
Respiration/ breakdown releases PO43-
Fertilisers: high in PO43-
Leaches into water bodies/ ocean
Excess stimulates algal growth/ eutrophication
Use of dissolved O2, death of other organisms
Biogeochemical cycling – Nitrogen
N2 in air is non-reactive, most organism can’t use
Non-fixing plants take up ammonium ions (NO4+) or nitrate ions (NO3-) – reactive N or “Nr”
Ammonium wastes are released
(Some) soil bacteria oxidise NO4+ to NO3-
Nitrogen fixers: bacteria use N2, live in association with legumes in nodules
Some bacteria can use nitrate instead of O2: denitrification
Excess fertiliser means excess Nr in water ways
Stimulates algal growth/ eutrophication
Use of dissolved O2, death of other organisms as with P
Nr Cascade
Nutrient pollution
Eutrophication(where excess nutrients encourage algal growth)
harmful algal blooms
highturbidity
creation of coastal low-oxygen dead zones
disruption of natural biogeochemical cycling
crown-of-thorns outbreaks,coral bleachingand coral disease in tropical areas.
eutrophication
When sewerage with a high BOD is discharged into a stream or small river, it creates an oxygen deficit and severely affects the stream’s biology
Water chemistry
Water dissolves gases and chemicals
The chemistry of any body of water relies upon the chemistry of the surrounding environment; i.e. the atmosphere that sits above it, and the water that runs into
Solar radiation
The Sun, (yellow dwarf star- at center of our solar system), is a hot ball gases. Its gravitational force holds everything in its orbit together.
The Sun-Earth relationship and interactions affect weather, temperature, radiation belts, seasons, ocean currents, and aurorae.
Albedo Effect
Not all incoming solar radiation makes it to the surface, and a lot of that which does, is reflected back into space, by reflective surfaces. The proportion of the energy that is reflected is called the Albedo Effect.
Greenhouse effect
Natural processes that warm the surface of the Earth
Solar radiation
Warms surface materials
Re radiated to atmosphere & space as infra-red
Some absorbed by greenhouse gases
Re emitted – FURTHER warming atmosphere and land
Wind patterns
Global wind patterns are formed from the heating and rising of the air at the equator, and the net energy loss from the Earth at the poles
Three Phases of ENSO Neutral
The normal wind pattern across the central Pacific is from East to West
This pushes the warmed surface waters towards the west of the Pacific Ocean
Creates Low Pressure systems and associated rain around Indonesia & Australia
Three Phases of ENSO El Nino
El Nino is associated with a decrease in the intensity of wind patterns moving East to West across the Central Pacific
This restricts the warm waters from being pushed to the west of the Pacific Ocean
Creates Low Pressure systems and associated rain around the Central Pacific
Three Phases of ENSO La Nina
Associated with an increase in the intensity of wind patterns moving East to West across the Central Pacific
This moves more warm water to the west of the Pacific Ocean
Creates Intensified Low Pressure systems and associated rain around the Indonesia and Australia
Southern Oscillation Index
Measure of the intensity of the Walker Circulation. Key atmospheric indices gauging strength of El Niño and La Niña events and potential impacts on the Australian region.
Sustained positive SOI values above +8 (La Niña) sustained negative values below –8 (El Niño).
Pressure Cells
Air moves out of high pressure cells and into low pressure cells in spiral.
Southern hemisphere- air circulates clockwise around a low pressure cell and anticlockwise around a high pressure cell.
Opposite occurs in northern hemisphere
Heat Capacity/Heat Sink
Heat Capacity is the amount of heat energy needed to raise the temperature of one unit amount of substance by one unit amount of temperature.
(e.g. oceans can store a huge amount of heat energy without changing temperature
oceans)
Ocean currents/Thermohaline circulation
Wind currents are a major influence on ocean currents – top 100 m.
Deep currents rely on density changes, impacted by salinity and temperature.
Thermohaline circulation
Driven by salt content which controls the density of the water.
More dense water sinks, and less dense water rises.
Carrying Capacity
Population that can be supported indefinitely by its supporting systems
Weathering
Carbon dioxide +other atmospheric gases dissolve in surface waters.
Hydrogen ions and water react with most common minerals (silicates and carbonates) altering the minerals.
Products of weathering are predominantly clay’s
Fossil Fuels
Were once living things- converted by heat and pressure over long periods of time into coal, oil or natural gas.
Release energy and carbon dioxide when burnt.
Made from fossilised remains of plants & animals.
Diagenesis
Plant and animal remains in top few 100m of deep ocean sediments are converted into sticky organic matter and biogenic gases due to activity of anaerobic bacteria
Catagenesis
Occurs at depth of 3-5 kms where heat and pressure convert the organic matter into thick organic material called kerogen and liquid petroleum
Metagenesis
Occurs at 3-5km or more in areas where there is extreme temperatures and pressures to convert the organic matter into thermogenic gases and a carbon rich residue.
Mineral exploration
Start Big, then Zoom In
1)Area selection
2)Remote sensing
3)Geological Mapping
4)Geochemistry
5)Drilling
Extraction of resource processes
1)Wellheads – used for liquid and gaseous petroleum (Enhanced Recovery, Fracking)
2)Dredging – used for solid resources within a liquid
3)Open cut mines – used for solid resources less than ~150 m in depth
4)Underground mines – used for solid resources greater than ~150 m in depth (Bord & Pillar, Longwall, Stoping)
Insolation Weathering
Expansion due to heating: because rock is a poor conductor expansion is uneven
Haloclasty (salt weathering) may also play a role in arid environments
Sand particles
Gritty feel
Can be seen with the naked eye
Hand sampling:
No residue left on hand
Silt particles
Dry: Powdery smooth feel, flour-like
Wet: Creamy slick, slippery feel
No sticky or plastic feel
Can be seen with a hand lens or microscope
Hand sampling:
Coats hand, able to brush off
Clay particles
Dry: Hard feel
Wet: Sticky, plastic feel
Can be seen with an electron microscope
Hand Sampling:
Sticks to fingers
Renewable resources
Can be replaced over a relatively short period of time (months, years or decades) e.g.water, food, natural fibres, wood and energy such as wind and solar
Non-renewable resources
Aren’t renewed quickly e.g. Petroleum takes more than 10,000,000 yrs to be produced. On human time scale they are not replaceable.
Replenishment of renewable resources
Sustainable use- over given time period, the amount used or removed from the system must be less than the amount that is replenished by the system
Precautionary principle
If the environment is threatened by serious or irreversible damage, a lack of full scientific certainty should not be used as an excuse for not attempting to reverse the damage
Intergenerational equity
The health diversity and productivity of the environment should be maintained or improved by the present generation for the benefit of future generations
Conservation of biological diversity
The conservation of ecosystems and the populations and varieties of species within them should be a fundamental consideration
Groundwater
Environmental factors should be included in the valuation of ecological assets and services
Geothermal energy
Driven by the global crustal temperature gradient, and as such is inexhaustible
Surface water
Simple rainfall runoff. . Locallised rates of recharge, dependent on landuse, climate, and saturation.
Solar Power
The sun is the largest source of energy available. The average solar insolation on earth is approximately 140W/m2.
3 types:
1)Photovoltaics (PV) – Standard Solar Panels
2)Concentrated solar thermal (CST) – uses concentrator to gather the heat to heat up a liquid for a turbine
3)Direct heating and lighting – not to create electricity but used passively for light and heat, like opening windows for heat and light
Wind Power
Wind energy is usually converted to electricity through wind turbines, using the kinetic energy from the wind to transform electrical energy.
Marine Power
Energy from the ocean comes in three main forms, from waves, tides, and from thermal differences between water bodies
Tidal Energy
Exists in two forms, both as potential energy from the vertical fluctuations in sea level, and as kinetic energy from ocean currents
Wave Energy
Can be captured both near shore and offshore, with most wave energy capturing technologies being installed on the ocean surface
Hydropower
Hydropower is generated when water moves between various elevations. This can either occur naturally in a river by water flowing downhill
Geothermal Energy
Geothermal heat is created either from the earth’s inner layer being close to the surface, or from the natural decay of radiogenic elements such as uranium, thorium and potassium
Biofuels
Bioenergy uses organic material (biomass) to produce energy for electricity as well as to produce heat. Biofuels consist of vegetable and animal derived organic materials, including wood, sugar cane residue and animal fats
