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prelim Flashcards

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1
Q

How did the geosphere form

A

Formed through accretion, where dust and gas particles came together under gravity. Over time, these materials collided, forming Earth’s solid layers, including the crust, mantle, and core.

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2
Q

How did the atmosphere form

A

Through outgassing, gases like carbon dioxide, water vapor, and nitrogen were released from molten Earth during volcanic activity. Gravity retained these gases, forming the early atmosphere, while some dissolved in rain.

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3
Q

How did the hydrosphere form

A

from water vapor released during outgassing and water delivered by meteorites. As Earth cooled, water condensed to form oceans and other bodies of water. It’s a key part of Earth’s water cycle.

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4
Q

How do seismic waves help scientists understand Earth’s structure?

A

Seismic waves provide evidence for the Earth’s internal layers, revealing concentric shells: a thin outer crust, mantle, liquid outer core, and solid inner core.

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5
Q

What are the characteristics of L Waves (Rayleigh waves)?

A

Type: Surface waves.
Speed: Slowest, most destructive.
Medium: Travel only along the Earth’s surface.

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6
Q

How do meteorites provide evidence for Earth’s structure?

A

Meteorites contain early solar system particles, helping reveal the age, composition, and density of Earth from its accretion.

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7
Q

What do meteorites show about Earth’s composition?

A

What do meteorites show about Earth’s composition?

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8
Q

What do meteorites reveal about Earth’s density?

A

Meteorites help confirm that Earth’s core is denser than its mantle and crust, demonstrating layer differences.

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9
Q

Why are meteorites important to Earth’s formation?

A

They provide evidence of the accretion process and early material that formed Earth.

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10
Q

What is the composition and thickness of the crust?

A

Oceanic crust:
Composed of mafic rocks like basalt and gabbro; 6-7 km thick, denser than continental crust.

Continental crust:
Composed of felsic rocks like granite and andesite; 20-70 km thick, less dense.

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11
Q

What is the lithosphere and its characteristics?

A

Composed of minerals rich in iron, aluminum, silica, and magnesium. It’s solid and dense, ranging from 40-280 km thick.

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12
Q

What is the composition and thickness of the asthenosphere?

A

Made of peridotite (rich in olivine and pyroxene), it’s semi-molten due to high temperature and pressure. Thickness: 440 km.

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13
Q

at is the composition and thickness of the mantle?

A

Composed of silicates like olivine and pyroxene. It’s mostly solid but moves plastically over time. Thickness: 2900 km.

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14
Q

What are the characteristics of the core?

A

Outer core: Liquid, composed of iron and nickel, thickness: 2200 km.
Inner core: Solid, composed of iron and nickel, creates Earth’s magnetic field. Thickness: 1220 km.

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15
Q

What do zircon crystals reveal about Earth’s age?

A

Zircon crystals, composed of silicate are the oldest known minerals on Earth, with ages up to 4.40 billion years. This dating indicates that Earth must be at least this old.

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16
Q

How do radiometric techniques determine Earth’s age?

A

Uranium-lead dating measures the decay of uranium isotopes into lead isotopes, providing an age estimate for Earth of 4.45-4.55 billion years. This is based on the known half-life of uranium isotopes.

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17
Q

How did Aboriginal and Torres Strait Islander peoples classify rocks and minerals?

A

They classified rocks and minerals based on their use for tools, ceremonial purposes, and their role in defining a sense of place.

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18
Q

What are felsic minerals and their characteristics?

A

Composition: Rich in silicon and aluminium, may include potassium.
Color: Light-colored.
Density: Lower than mafic minerals.
Examples: Quartz, plagioclase, orthoclase, muscovite mica.

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19
Q

What are mafic minerals and their characteristics?

A

Composition: Rich in iron and magnesium.
Color: Dark-colored, ranging from green to black.
Density: Higher than felsic minerals.
Examples: Olivine, pyroxene, amphibole, biotite mica.

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20
Q

How is hardness used to classify minerals?

A

Hardness measures a mineral’s resistance to scratching, assessed using Mohs hardness scale, which ranks minerals from 1 (talc) to 10 (diamond).

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21
Q

What is the difference between cleavage and fracture in minerals?

A

Cleavage: Breaks along smooth, flat surfaces due to weak bonds in the crystal structure.
Fracture: Breaks along irregular, rough surfaces.

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22
Q

What does luster tell us about a mineral?

A

describes how light reflects off a mineral’s surface, categorized as vitreous, metallic, dull, or earthy.

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23
Q

How are color and streak used to identify minerals?

A

Color: General appearance; less reliable for identification.
Streak: The color of the powder left when a mineral is rubbed on a streak plate; more diagnostic.

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24
Q

How are igneous rocks formed?

A

From magma crystallizing. Intrusive (coarse-grained) cools slowly inside Earth; extrusive (fine-grained) cools quickly on the surface.

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25
How do sedimentary rocks
From weathered materials like particles and clay. Clastic rocks come from rock fragments, while chemical rocks form from mineral precipitation.
26
How are metamorphic rocks formed?
From existing rocks subjected to high temperature and pressure. Foliated rocks show layers from pressure, while non-foliated rocks form with high temperature but low pressure.
27
What is soil and how is it formed?
Soil is weathered material at Earth's surface, derived from parent rock. It forms through the interaction of atmospheric, geologic, hydrologic, and biotic processes.
28
What are the components of soil?
Mineral matter: From weathered parent rock. Organic matter: Litter and decomposed materials. Water: Fills pores between soil grains. Air: Found in the soil's pore spaces.
29
What are soil horizons and their characteristics?
O horizon: Surface layer of decomposed plant material. A horizon: Topsoil, dark and loamy, with leaching. B horizon: Subsoil, finer, denser, and more colorful. C horizon: Weathered parent material. D horizon: Below soil profile, differing from parent material.
30
What factors affect soil formation?
Climate Topography Organisms Time
31
What is relative dating?
Order: Arranges geological events. Method: Uses stratigraphy. Result: Provides a relative age (older or younger).
32
What is absolute dating?
Exact Age: Calculates precise age. Method: Measures physical properties. Example: Radiocarbon dating using carbon isotopes and half-life.
33
What did Wegener contribute to the theory of plate tectonics?
Year of Work: Early 1900s Answer: Proposed the idea of Pangea and continental drift. Provided evidence through the matching of fossils across continents and the jigsaw fit of coastlines. Initiated discussions about plate movement but lacked an explanation for how plates moved.
34
What was Holmes’ contribution to plate tectonics?
Year of Work: 1910-1965 Answer: Introduced the concept of convection currents in the mantle as the mechanism for plate movement. First used radiometric dating to measure rock ages, providing a mechanism that supported Wegener’s theory.
35
What did Hess propose regarding seafloor spreading?
Year of Work: 1962-1969 Answer: Developed the theory of seafloor spreading, which linked it to plate tectonics and unified geological understanding. His ideas were confirmed by later studies showing older rocks farther from mid-ocean ridges.
36
How did Vine and Matthews contribute to plate tectonics?
Year of Work: 1960s Answer: Mapped seafloor magnetic anomalies and demonstrated symmetrical magnetic reversals on either side of mid-ocean ridges, confirming seafloor spreading and providing evidence for plate movement.
37
What was the role of the Glomar Challenger in plate tectonics research?
Year of Work: 1968-1983 Answer: Conducted deep-sea drilling that provided evidence for the age of oceanic crust, confirming the theory of seafloor spreading by showing that the ocean floor’s age increases with distance from mid-ocean ridges.
38
What occurs at divergent boundaries with oceanic plates?
: Oceanic-Oceanic Answer: Two oceanic plates move apart, allowing magma to rise and form new oceanic crust. This leads to the creation of mid-ocean ridges, with high volcanic activity and shallow-focus earthquakes.
39
What happens at convergent boundaries between oceanic and oceanic plates?
One oceanic plate subducts beneath another, forming a trench and volcanic island arc. This process is associated with deep and shallow-focus earthquakes and volcanic activity.
40
How do convergent boundaries between oceanic and continental plates behave?
Question: Oceanic-Continental Answer: The oceanic plate subducts beneath the continental plate, creating a trench and volcanic mountain range. This boundary is characterized by explosive volcanic activity, deep and shallow-focus earthquakes, and formation of accretionary wedges.
41
What is observed at convergent boundaries between continental plates?
Question: Continental-Continental Answer: Two continental plates collide, causing crustal folding and uplift to form mountain ranges. This boundary generally shows minimal volcanic activity and shallow-focus earthquakes.
42
What occurs at transform boundaries?
Two plates slide past each other horizontally, causing faults. This type of boundary is known for high earthquake activity along transform faults but lacks volcanic activity.
43
What is a Rift Valley and how does it form?
A Rift Valley forms where divergent plates extend, causing the land between them to thin and sink, creating a valley. Example: The Great Rift Valley, Kenya.
44
What is a Mid-Ocean Ridge and how does it form?
A Mid-Ocean Ridge forms along divergent plate boundaries where new ocean floor is created as tectonic plates spread apart. Example: Mid-Atlantic Ridge, Atlantic Ocean
45
What is a Normal Fault and how does it form?
Answer: A Normal Fault forms when rock above an inclined fracture plane moves downward along the fracture. Example: Wasatch Fault, USA.
46
What is a Transform Fault and how does it form?
A Transform Fault is a strike-slip fault where horizontal slip accommodates movement between tectonic boundaries. Example: San Andreas Fault, USA.
47
What is a Mountain Range and how does it form?
A Mountain Range forms when colliding continental plates crumple and fold, creating mountains. Example: Himalayas, China,
48
What is a Trench and how does it form?
A Trench forms through subduction, where an older, denser plate is pushed beneath a lighter plate, creating a steep depression. Example: Mariana Trench, South Pacific Ocean.
49
What is a Reverse Fault and how does it form?
A Reverse Fault forms due to compression, causing one side of the fault to move above the other. Example: Himalayan Mountains.
50
What are Folds and how do they form?
Folds are created by the compression of existing rock layers, causing them to shorten and fold. Example: Scottish Highlands, Scotland.
51
What is the boiling point of water at different altitudes?
Boiling point is 100°C at sea level. It decreases by ~1°C per 300 meters. At 5,380 m (Mount Everest base camp), it’s ~81°C.
52
Why is water's ability to act as a solvent important?
Water dissolves many substances due to its polarity, essential for biological processes.
53
How does ice’s density compare to water and why does it matter?
Ice is less dense (0.9 g/cm³) than water (1 g/cm³) and floats. This prevents ice from sinking, protecting marine life.
54
What is water's thermal capacity and why is it important?
Water’s thermal capacity is 4.18 J/g/K, helping regulate temperatures in organisms and environments.
55
How does water’s polarity affect its properties?
Water’s polarity makes it sticky, influencing its solvent capabilities and surface tension.
56
What causes surface tension in water?
Polarity creates stronger forces at the surface, allowing insects to walk on water and aiding plant water transport.
57
How do surface currents form and their role?
formed by water mass movements, they create gyres and connect with deep currents in global circulation.
58
How does salinity affect ocean water density?
Higher salinity increases density, causing water to sink and drive deep ocean currents.
59
How are deep water currents formed at the poles?
Cold, saline water sinks at the poles, forming deep currents that spread globally.
60
What is needed for continuous thermohaline circulation?
Deep currents from the poles merge and rise at the surface, linking global water circulation.
61
How do El Niño and La Niña occur?
Changes in heat transfer and Walker circulation can shift warm water in the Pacific Ocean, causing El Niño (warm conditions) or La Niña (cooler conditions). These events affect global climate patterns.
62
What is the effect of the Indian Ocean Dipole?
it disrupts regional climate, affecting conditions like droughts and bushfires in Australia.
63
how is global warming affecting glaciers and permafrost?
Melting glaciers raise sea levels; melting permafrost releases methane and alters ecosystems.
64
What are the effects of cryosphere changes on biomes?
Changes alter water systems and habitats, impacting ecosystems and climate patterns.
65
How is water distributed on Earth and what is available to plants and animals?
Oceans: ~97% Freshwater: ~3% Freshwater distribution: Glaciers/ice caps: ~68% Groundwater: ~30% Surface water (rivers, lakes): ~1% Available to plants/animals: Mainly surface water and groundwater.
66
What factors affect water distribution?
Topography: Influences flow patterns of rivers and rain clouds. Latitude: Deserts near tropics; rainforests near the equator. Climate: Affected by ocean currents, trade winds, and other factors.
67
What is industrial wastewater and how is it treated?
Waste from industrial processes with organic/inorganic chemicals. Treatment: Multi-stage process, including physical, chemical, and biological methods.
68
How is sewage treated and what are its effects?
Definition: Pollutant from body waste. Treatment: Aeration, chemical treatment, filtration, and settling of solids. Effects: Can cause environmental harm if untreated.
69
What is stormwater and how is it managed?
Rainwater running off surfaces, carrying pollutants. Management: Use of pollution traps, retention of porous surfaces.
70
What causes water scarcity?
Physical shortage, inadequate infrastructure, or institutional failure.
71
How do dams affect water flow?
Alters flow, causing upstream swelling and reduced downstream flow.
72
How does irrigation impact water quality?
Causes erosion, nutrient runoff, and heavy metal transport, affecting water levels and aquatic life.
73
What causes algal blooms and their impact?
Eutrophication from excess nutrients. Impact: Blocks sunlight, releases toxins, and depletes oxygen, making water anaerobic.
74
What are pathogens, and how do they affect water quality?
Pathogens are disease-causing organisms like Giardia and Cryptosporidium contaminate. water supplies,
75
How do nutrients affect water quality?
Nutrients (e.g., nitrogen, phosphorus) from fertilizers promote excessive plant growth, leading to algal blooms that can degrade water quality and harm aquatic life.
76
What impact do sediments have on water quality?
Sediments from erosion and land clearing make water murky, reduce light penetration for aquatic plants, and can affect overall water clarity.
77
How do synthetic organic compounds affect water quality
Synthetic organics, such as petroleum products, can float on water, blocking sunlight and harming aquatic organisms.
78
What are the effects of inorganic chemicals on water quality?
Inorganic chemicals, like pesticides and industrial waste, can disrupt ecosystems and cause health issues in humans, including cancer and neurological disorders.
79
What are the effects of radioactive substances on water quality?
Radioactive substances damage DNA, causing diseases and mutations. They are problematic in areas affected by nuclear accidents
80
How do thermal discharges impact water quality?
Thermal discharges from industrial cooling decrease oxygen levels in water, which can affect plant and animal life.
81
What are oxygen-demanding substances, and how do they impact water quality?
Oxygen-demanding substances, such as untreated sewage, decompose in water, using up oxygen and reducing availability for aquatic life.
82
How does land clearing contribute to salinisation?
Land clearing removes vegetation that absorbs water, causing water tables to rise and bringing salts to the surface, increasing soil salinity.
83
How does irrigation lead to salinisation?
Irrigation can raise water tables, bringing dissolved salts to the surface, which increases soil salinity and can lead to environmental issues.
84
What is the role of weathering and erosion in salinization
Weathering and erosion can expose salts in the soil, which, when combined with rising water tables, contribute to increased soil salinity.
85
How does Australia’s soil fertility relate to salinization?
Australian soils, especially in the west, are naturally low in fertility. Increased salinity from rising water tables exacerbates soil fertility issues.
86
How do rivers contribute to soil salinity
Rivers can become more saline by drawing in water from oceans or dissolving salts from surrounding rocks and soils.
87
What are the biotic effects of introduced terrestrial plants?
Introduced plants can outcompete native species for resources, alter soil chemistry, and reduce biodiversity.
88
How do introduced terrestrial animals impact the environment?
Introduced animals can reduce native species, disrupt agriculture, and contribute to soil erosion and compaction.
89
What are the abiotic effects of introduced aquatic plants and animals?
Introduced aquatic species can reduce biodiversity and affect water oxygen levels.
90
Why were cane toads introduced, and what are their effects?
Cane toads were introduced to control sugar cane pests. They are highly toxic to predators and contaminate water systems.
91
How do human activities support the spread of cane toads?
Irrigation and water sources created new habitats for cane toads, aiding their spread.
92
What control methods are used for cane toads?
Cane toads are controlled by hand collection, traps, and barrier fencing.
93
What is the economic impact of cane toads?
Cane toads impact agriculture by consuming beneficial insects and pose economic threats, leading to significant expenditure on control measures.
94
What was the reason for introducing prickly pear, and what are its effects?
Prickly pear was introduced for a cochineal industry. It outcompetes native species and absorbs nutrients, affecting soil health.
95
What control methods were used for prickly pear?
The Cactoblastis cactorum moth was introduced as a biological control, effectively reducing prickly pear populations.
96
What is the economic impact of prickly pear?
Prickly pear caused significant economic damage to farmland and required costly eradication efforts, though biological control eventually succeeded.

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