Earth notes Elizabeth Barter PDF

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Module 5: Developing of the Biosphere Investigate evidence for the origin of organic molecules on the earth including: Urey and Miller experiment

o Demonstrated that complex organic molecules can form naturally under conditions such as those on earth o This showed that under the right conditions, organic molecules can form spontaneously from inorganic ingredients, illustrating one way from which life may have originated from

Communities around black smokers

o Life began on the ocean floor near hydrothermal vents. These hydrothermal vents heated the water which may carry sulphides that react with chemicals in the sea water to create ‘black smokers’ o Large amounts of methane and ammonia produce amino acids, which react with the clay particles o This is most likely where the earliest living cells evolved o Exotic ecosystems based on chemosynthesis are thriving in deep oceans along tectonic plate boundaries, where volcanic vents are common

Meteorites and panspermia

o The theory that amino acids come from elsewhere in the universe, brought via collisions on earth from comets and meteors, then evolved on earth o Main evidence is that organic chemicals have been detected in comets and interstellar dust clouds

Investigate the evidence for the development of photosynthetic life, including: o Cyanobacteria: photosynthetic bacteria that creates oxygen as a by-product. It grows in high-saline conditions, shallow, warm water. It is one of the oldest known fossils and is linked to carbon dating. o Stromatolites: dome shaped structures built overtime from cyanobacteria and sediments Evaluate the evidence for the origin of multicellular life and resulting changes to ecosystems for example: o Ediacaran: these organisms lived in a shallow marine environment. All these early creatures lack the rigid, supporting skeletons and protective shells o Cambrian: from the Cambrian explosion, where suddenly the fossil record is dominated by animals with hard parts • Preserved animal burrows mark the Cambrian o These trace fossils allow radiometric dating to occur (also known as absolute dating) Investigate the conquest of land by both plants and animals o Animals lived in the sea due to the U.V. rays o The ozone layer formed when there was enough oxygen being produced by photosynthesis o Footprints, trace fossils show animals may have grown legs. Arthropods (centipede-like creatures) were the first evidence of animals on land

Module 5: Changes in the Geosphere, Atmosphere and Hydrosphere Analyse the changes in the geosphere, atmosphere and hydrosphere that resulted in the development and evolution of the biosphere, for example: o Effect of photosynthesising cyanobacteria on each of the spheres Geosphere o Lack of oxygen allowed iron to stay is soluble form in the water and when oxygen was created (cyanobacteria photosynthesising); it reacted with the soluble iron and precipitated, forming thin layers on the ocean floor. Very little of this oxygen would have entered the atmosphere due to amount of dissolved iron in the ocean. Formation of BIFs stopped around 1.7 b.y.a., which suggests all sediment may have been removed. Once removed, oxygen could enter the atmosphere. Atmosphere

o Early atmosphere contained substantial amounts of carbon dioxide, which dissolved and reacted with water, this caused ‘carbon sinks’, where carbon is ‘locked up’ in oceans, decreasing the carbon dioxide level in the atmosphere. Some carbon sinks are animals (carbon locked in cells, tissue, fats and proteins, which, when the animals die and decay, will be released back into the atmosphere), fossil fuels (coal and petroleum deposits, which, when burnt, release carbon back into the atmosphere), skeletons and shells (often formed from calcium carbonate extracted from the ocean. These do not decompose easily, adding to the limestone deposits in the ocean) and the oceans (which contain more carbon than present in the atmosphere) o Ozone layer could have been formed 500 m.y.a. from left-over oxygen from the cyanobacteria, which blocked U.V. rays which made it possible for animals to inhabit the land

Hydrosphere

o Oxygen entering the atmosphere caused the temperature of the globe to drop, causing global cooling, leading to glaciation (scientists believe the earth has frozen over several times since the introduction of oxygen into the atmosphere)

Role of oxygen in the production of banded iron formations • Oxygen oxides the dissolved iron from the weathering of Proterozoic rocks. This oxidised iron is insoluble and forms a sediment, which creates another layer in the lithosphere • However, as the oxygen increased and the dissolved iron increased, cyanobacteria died off, due to the toxic environment of too much oxygen. This dying resulted in less oxygen, thus less iron-rich layers in the lithosphere

Module 5: Plate Tectonic Supercycle Outline the effect of the plate tectonic supercycle on large scale phenomena, including: Climate o If there is one single continent, the climate is colder and drier with low sea levels, along with minimal volcanic activity and low carbon dioxide levels. Reduced greenhouse effect = reduced average temperatures = less evaporation = lower rainfall and permanent ice caps which lower sea level, with desert environments (cold and warm) being the most common o Many little continents = more rifting and subduction = more volcanic activity = increased carbon levels. The greenhouse effect increases global temperatures = more rainfall and more evaporation, less ice caps which means higher sea level. Desert ecosystems are less common, rainforests more common, coral reefs thriving due to higher sea level Evolution o One continent: less diversity and evolutionary divergence in animal species due to less isolation and the need to adapt o Multiple continents: split continents lead to more diversity as the species needs to adapt to survive to their new environment and isolated habitats, increased evolution and higher rates of biological diversity

Module 5: Fossil Formation and Stratigraphy Investigate processes of fossil formation by examining a variety of methods in rock, including: o Occur when the organism has been buried in sediment. After some time, the sediment becomes compressed around the organism, Mould formations forming an internal or external mould o Start as moulds, which then are filled with new sediments or groundwater that percolates and later crystallises minerals inside. They are Cast formations normally 3D in appearance. o Excellent environment indicators due to the behaviour of animals often being influenced by environmental factors Trace fossils o They provide important clues to the original conditions of ancient environments. These include salinity and oxygen levels, food and energy supplies, as well as organismal interactions o Tracks (footprints): These can indicate animal activity formed on land, in swamps or beach environments. The distance between each footprint is often used to find the speed of the animal as well as leg length. The depth of the print can give an estimate of the mass of the animal o Trails (feeding trails): Includes the burrow of sediment feeders. These burrows may be multi branched or dendritic and may consist of large vertical and horizontal branching tubes o Burrows: soft bodied organisms often burrow in sediment, may be single burrows and can be u-shaped (can indicate way up) or 3D Discuss the significance of index fossils in generating a geological time scale o Index fossils are organisms that existed for short periods of geological time o They are distinctive and easy to tell from other rocks o They give us relative dates that gauge how old other rocks are Extrapolate how the principles of uniformitarianism and superposition as well as fossils and absolute dating can be used to date events of geological significance, for example: The evolution of the Cambrian fauna

Mass extinction events o Large number of species extinct over a large global area. Often caused by natural catastrophes or dramatic environmental change

o “Cambrian Explosion”: when animals started to appear on land o Previously only soft-bodied, aquatic creatures o Produced the first representatives of today’s phyla • Cretaceous: mass extinction with large amounts of volcanic materials. Estimated 60-70% of all marine species and nearly 15% of all land species went extinct. This is the dinosaur extinction. Clay boundaries – use radiometric dating • Permian: also called the great dying. Around 96% of marine species and 70% of terrestrial species went extinct. Permian strata has many fossils. Eruptions and changes to climate evident. • Cambrian: this extinction event eliminated many brachiopods and conodonts and severely reduced trilobite species, however fossils of planktonic graptolites, conodonts and trilobite species appeared

• Uniformitarianism: the theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform processes and that all the natural processes and scientific laws we observe here and now are the same throughout time and throughout the universe • Superposition: older layers of the earth are always lower down (see picture, but don’t write that)

Module 6: Geological Natural Disasters Using data, predict the zones along which earthquakes and both effusive and explosive volcanic eruptions are likely to occur and relate these to plate boundaries o Oceanic – continental convergence: oceanic crust subducted under continental crust. The magma at this boundary is rich in silica, which makes it more viscous. This makes eruptions near the boundaries explosive, due to the high amount of pressure being built up (same as oceanic – oceanic) o Divergent boundaries: two plates separate, forming new crust between them. The magma at this boundary is low in silica, meaning it flows easily and does not allow pressure to build up. This makes the eruption effusive. Using secondary sources, investigate and model the changing depth of the focus of earthquakes at: o Convergent: boundaries are prone to shallow/deep focus earthquakes • Deep: (up to 700km) arise from the friction of the descending plate with the overriding plate and mantle • Shallow: result of either the movement along fault lines within the folded mountains or the displacement of rocks when magma rises and falls o Divergent: boundaries with shallow focus earthquakes only Using secondary sources, investigate and explain the hazards associated with earthquakes, including: o Ground motion • The earth shake as the seismic waves “energy” (which has been stored up) is released • Large enough waves can sometimes damage buildings and infrastructure, cliffs and sloping ground • Ground shaking will often vary due to: o Location, orientation of the fault rupture o Topography (the way the ground is shaped) o Bedrock type o Tsunami • Series of seismic waves that cause the displacement of water (usually a large volume) Using secondary sources, investigate and explain the hazards associated with volcanoes, for example: Ash eruptions and lava flows:

Lahars and poisonous gas emissions

o Ash eruptions are prominent features of explosive volcanoes. It does not reflect on the aircraft radar, making it a hazard for aircraft flying at night. It can cause the collapse of buildings due to the build-up of ash on rooftops, and if mixed with rain it can increase the weight. It can contaminate water supplies and smother crops and pastures o Pyroclastic flows carry rock particles and often spew them in the air, causing rocks and pieces of debris to tumble down and often cause damage. This also includes hot gases in the flow o Lahars are a type of flooding: when fast flowing water mixes with ash from the explosion (kind of like wet cement). It erodes gullies and grows as it moves along, taking anything and everything with it and gaining speed (up to 60km/h or more) o Sulphur dioxide is released into the air during an eruption. These gases can block out the sun, and even carry to other parts of the world if it gets high enough (troposphere level). These gases can also cause temperature to drop (often globally)

Account for the types of magma in each of the above types of volcanoes, and analyse how this affects the explosivity of their eruptions o Convergent: magma rich in silica, more viscous, therefore more explosive o Divergent: magma low in silica, flows easily, therefore effusive o Effusive: generally at hotspots, mantle comes directly to surface, hot lava, low viscosity, very mafic, flows easily, forms shield and flood basalt volcanoes o Explosive: found at subduction zones, low temperature magma, high viscosity, felsic, hard to predict eruptions, forms composite volcanoes and very destructive Investigate the point at which a geological hazard becomes a disaster o Hazard: a threat (natural or human) that has the POTENTIAL to cause loss of life, injury, socio-economic disruption or environmental degradation o Disaster: a major hazard, that causes widespread disruption with significant demographic, economic and environmental loss (the affected community needs outside help)

Module 6: Impact of Natural Disasters on the Biosphere Using data from secondary sources, compare the eruptions that occur at explosive and effusive volcanoes in terms of the impact on the biosphere and atmosphere o Biosphere: not affected much, however 800 people died from ash on roofs Mt Pinatubo – explosive causing them to collapse o Atmosphere: nearly 20 million tonnes of sulphur dioxide spread across the globe, dropping temperatures by 0.5ºC Mt Kilauea – effusive o Biosphere: villages were lost to the lava flow in 1986 and a few roads were cut off o Atmosphere: not much, due to being effusive, sulphur dioxide emissions are common, however they are gradual Analyse the effects of a major volcanic eruption on the atmosphere in terms of changing the climate (both warming and cooling) o Warming: • Very little record of any warmer temperatures after explosions o Cooling: • Often, eruptions will cause a decrease in temperature by up to 1ºC, due to the amount of sulphur expelled into the atmosphere, reflecting the rays from the sun In a case study, investigate one eruption that has had a significant effect on the biosphere and atmosphere and assess its impact, including but not limited to: o Mt Pinatubo: • Biosphere: o 800 people dying to collapsing roofs from heavy ash that fell from the volcano • Atmosphere: o 20 million tonnes of sulphur dioxide spread across the globe, dropping temperatures by up 0.5ºC

Evaluate the causes and physical impact of climatic phenomena on a local ecosystem, including: Hailstorms

East coast lows

Droughts

Floods

o Form of solid precipitation o Balls or irregular lumps of ice are called hail stones o Impacts: • Injury to wild life • Destroying trees and vegetation o Causes: • Form within unstable air masses • Temperature has to be right to keep the developing hailstones forming o Intense low pressure systems that occur off the east coast of Australia o Impacts: • Can cause coastal erosion and flooding • HOWEVER • Important for water security bringing the heavy soaking rainfall that fills dams along the coast and the tablelands as well as replenishes rivers, creeks and wetlands o Causes: • Form in a variety of weather situations • Warm eddies also contribute to their development o A natural disaster of below average precipitation o Results in prolonged shortages in the water supply, whether atmospheric, surface water or ground water o Impacts: • Everything is affected and some abiotic and biotic factors recover, some never do: o droughts lower the quality of soils, as there is less organic activity, more wind erosion and soil insects and organisms perish o water bodies dry out, water animals die, food chains and ecosystems are affected o desertification o animals migrate long distances and end up in habitats, making them vulnerable o a natural event or occurrence where an area is covered with water o some can occur suddenly and recede quickly or takes months to build and discharge • impacts:

Investigate how human activities can contribute to the frequency and magnitude of some natural disasters, including:

o Increased water usage from industrialisation, significant growth in population, agriculture and industry o Human water use has exceeded available renewable water supply in many part of the world o Development and growth also increased greenhouse emissions which alter precipitation patterns

o deforestation • lack of vegetation encourages water to flow off the surface o poor land use

o habitats destroyed o chemicals and hazardous substances contaminate water o insects are introduced (potentially with diseases) upsetting natural balance

Bushfires

Landslides

o Physical part of combustion o Needs heat, oxygen and fuel (wood, leaf litter etc) o Impacts: • Loss of plant and animal life o Vegetation is destroyed, animals are killed due to lack of habitat, high temperatures and suffocation from the smoke • Reproduction: o Fire generates regrowth and new life ▪ Some eucalypt species and plants need it to be able to reproduce

• slash and burn agriculture, over cultivation and overgrazing eventually cause soil to become infertile o urbanisation • leads to replacement of permeable soil with pitch and concrete, which water cannot penetrate o improper waste disposal • garbage is not properly disposed of and enters into drainage systems and clogs them, which leads to a build-up of water • can also obstruct natural flow of rivers o quarrying • clearing of land results in more runoff o Arson (deliberately lit) o Discarding of cigarettes improperly o Not adhering to fire bans or fire safety

o Deforestation o Changes to the flow of groundwater o Destruction of vegetation by caused landslides o Droughts, fire and logging

Module 6: Prediction and Prevention of Natural Disasters Evaluate the effectiveness of technologies in predicting natural disasters, for example: o Volcanoes Three-dimensional imaging Seismic data

Early-warning systems

Ground-movement data

Analysis of historical data

o New technology along with the use of GPS to measure the change in shape of a volcano, as well as radar to measure movements of volcanos o Judgement: effective. New technology is always evolving, meaning better detection. Also, learning opportunities may arise o Helps with the prevention of loss of life, as small and increasing tremors and movements often result in a bigger earthquake happening o Judgement: effective. Although there are multiple tremors that can possibly happen, scientists have figured the types out: • Short period quakes: when ground moves along a fault. Related to fracturing of brittle rock, usually as the magma moves up • Long period earthquakes: indicate increased gas pressure • Harmonic tremors: occur when there is sustained movement of magma, usually below the surface. o (mentioned above) The magma moving into the volcano usually causes swelling of the volcano, indicating a possible eruption o Gas measurement is also an indicator, as an increase in gas usually indicates an increase in magma near the surface of a volcano. o Judgement: effective, however could lead to false alarm. o Along with gas emissions and harmonic tremors, ground movement data can be used to predict an earthquake. Tilt meters can be used to measure the ground tilt (or rotation) of the land, especially near known fault lines. These meters can be used to measure the uplift of a volcano or the fault slip o Judgement: effective. The meters are put in places where the accuracy cannot be tampered with e.g. the swelling of ground after rain. o Look at the historical eruptions and charts from the earthquakes, and identify trends, biggest rest periods = bigger eruptions o Judgement: not effective. Multiple volcanoes are overdue, such as Yellowstone, as well as past eruptions such a...