Earth Science Lecture Weeks 1 – 5 Review

These flashcards cover key theories, planetary facts, Earth systems, rocks and minerals, energy, soils, water resources, and environmental considerations discussed in Weeks 1–5 of the Earth Science course.

Cosmic Inflation Theory (1981)

It began with a singular explosion followed by a rapid inflationary expansion of a vacuum-energy bubble that cooled to form matter, radiation, stars and galaxies.

Who proposed the Steady State Theory

Fred Hoyle

Georges Lemaître’s Big Bang Theory

That all distant galaxies are receding from us, implying they were once concentrated in a single ‘primordial atom’ that exploded.

In the Accretion Theory of solar-system formation, what causes dust grains in the nebula to stick together?

Collisions combined with gravity, gradually forming larger bodies that become planets and stars.

Protoplanet Theory?

A dense interstellar cloud fragments into blobs; the largest blob forms the star while smaller blobs become planets and satellites.

How does the Capture Theory explain the formation of giant planets and their satellites?

Material drawn from a nearby protostar condensed into the filament, forming giant planets and their moons.

According to the Modern Nebular Theory, where did the planets originate?

In a dense disk of gas and dust that collapsed around the young Sun; density had to allow planet formation yet be thin enough for excess matter to be blown away.

Approximately how old is the Solar System?

About 4.6 billion years.

List three general traits of terrestrial planets.

Small size/mass, high density rocky composition, few or no moons and no rings.

List three general traits of Jovian planets.

Large size/mass, low density gaseous composition (H, He), many moons and rings, no solid surface.

Which planet is nicknamed “The Shrinking Planet” and why?

Mercury; cooling and contraction produced faults that criss-cross its surface.

Why is Venus the hottest planet in the Solar System?

Its thick CO₂ atmosphere creates an extreme greenhouse effect.

What makes Earth unique among planets?

Presence of abundant liquid water, oxygen-rich atmosphere, moderate climate, and known life.

Which planet is called “The Red Planet” and what causes its color?

Mars; iron-oxide (rust) dust on its surface.

State two reasons Jupiter has a massive magnetic field.

Its rapid rotation (≈9.8 h) and a deep layer of liquid metallic hydrogen that conducts electricity.

What feature makes Saturn instantly recognizable?

An extensive, highly reflective ring system composed mostly of water-ice particles and rocky debris.

Why is Uranus nicknamed the “Sideways Planet”?

Its spin axis is tilted about 98°, causing it to rotate on its side (retrograde rotation).

How long is one Neptune year?

Approximately 164.8 Earth years.

State the three IAU criteria (2006) that define a planet.

(1) Orbits the Sun. (2) Has sufficient mass to be nearly round. (3) Has cleared its orbital neighborhood.

Which IAU criterion disqualifies Pluto as a major planet?

It has not cleared the neighborhood of its orbit.

Where is Ceres located and why is it a dwarf planet?

In the asteroid belt; it is nearly round but shares its orbit with many asteroids.

Which dwarf planet is the farthest known from the Sun?

Eris (≈560‐year orbit).

Name two key conditions that make Earth habitable.

Location in the circumstellar habitable zone (liquid-water range) and a protective magnetic field.

What are the four major Earth systems studied in Earth science?

Atmosphere, Hydrosphere, Geosphere, Biosphere.

Give the approximate composition of Earth’s atmosphere.

78 % nitrogen, 21 % oxygen, 0.9 % argon, traces of CO₂, methane and other gases.

Which atmospheric layer contains the ozone layer?

The Stratosphere.

In which layer of the atmosphere do auroras occur?

Thermosphere (Ionosphere region).

What is the coldest atmospheric layer?

Mesosphere.

Which boundary separates the crust from the mantle?

The Mohorovičić discontinuity (Moho).

What discovery is attributed to Inge Lehmann?

The Lehmann discontinuity marking the boundary between outer and inner core.

What is the primary driver of plate tectonics?

Mantle convection powered by Earth’s internal heat.

Define the Hydrologic Cycle.

The continuous movement of water through evaporation, transpiration, condensation, precipitation, percolation and runoff, driven by solar energy.

Name two processes by which water vapor enters the atmosphere.

Evaporation and transpiration.

What percentage of Earth’s water is fresh?

Only about 3 % (two-thirds of which is in ice).

During photosynthesis, what happens to CO₂ and O₂?

CO₂ is absorbed (sequestered) and O₂ is released.

Which biome has the greatest biodiversity on Earth?

Tropical Rainforest biome.

What climatic conditions characterize the Desert biome?

Very low precipitation (<12 in/yr) and extreme temperature ranges.

Define a mineral (five key characteristics).

Naturally occurring, inorganic, solid, definite chemical composition, ordered internal (crystalline) structure.

Why is volcanic glass (obsidian) not a true mineral?

It lacks an ordered internal crystalline structure; thus it is a mineraloid.

Differentiate intrusive and extrusive igneous rocks by texture.

Intrusive rocks cool slowly, forming coarse (phaneritic/pegmatitic) crystals; extrusive rocks cool quickly, yielding fine (aphanitic or glassy) textures.

What causes a vesicular texture in volcanic rocks?

Gas bubbles escaping as lava solidifies rapidly.

How are clastic sedimentary rocks formed?

By compaction and cementation (lithification) of rock and mineral fragments.

Give two examples of non-clastic (chemical/biologic) sedimentary rocks.

Limestone and rock salt (halite).

What is foliation in metamorphic rocks?

Alignment of platy or elongated minerals under directed pressure, creating layered textures.

Outline the general steps of the rock cycle beginning with magma.

Magma cools to igneous rock → uplift/weathering produces sediments → lithification forms sedimentary rock → heat/pressure forms metamorphic rock → melting yields magma.

Name the seven major groups of rock-forming minerals.

Silicates, Oxides, Sulfides, Sulfates, Halides, Carbonates, Native metals.

Which common mineral has Mohs hardness 10?

Diamond.

What property measures the density ratio of a mineral to water?

Specific gravity.

Define an ore deposit.

A mineral deposit economically profitable to mine for its valuable minerals.

What is a magmatic ore deposit?

An ore concentrated within an igneous body by processes such as crystal settling or partial melting (e.g., chromite layers).

Describe a placer deposit and give an example.

Heavy, resistant minerals concentrated by flowing water; e.g., gold in stream gravels.

Differentiate metallic and non-metallic mineral resources.

Metallic resources contain extractable metals and exhibit metallic luster; non-metallic resources do not yield metals and have non-metallic appearance (e.g., gypsum, sand).

List five renewable energy sources.

Solar, Wind, Hydroelectric, Geothermal, Biomass.

Name the three main fossil fuels.

Coal, Petroleum (oil), Natural gas.

Explain how solar photovoltaic cells generate electricity.

Light excites electrons across a semiconductor junction, creating an electric current.

What drives wind on Earth?

Uneven heating of Earth’s surface causing air to move from high to low pressure areas.

Define geothermal gradient.

Rate of temperature increase with depth inside Earth.

Why is nuclear energy considered non-renewable in practice?

Although fission releases large energy, the uranium fuel is finite and not replenished on a human time scale.

State two environmental benefits of renewable energy use.

Reduces greenhouse-gas emissions and diversifies energy supply, lowering dependence on fossil fuels.

What is the pedosphere?

The ‘living skin’ of Earth, consisting of soil formed by interactions of atmosphere, biosphere, geosphere and hydrosphere.

List the four major components of good healthy soil and their typical percentages.

Mineral particles 45 %, Water 25 %, Air 25 %, Organic matter 5 %.

Name the five factors of soil formation.

Parent material, Climate, Topography, Organisms, Time.

Which soil horizon is rich in organic humus and called topsoil?

The A horizon (surface horizon).

What soil texture is ideal for agriculture and why?

Loam; it balances drainage/aeration of sand with nutrient and water retention of clay.

Describe Entisols.

Young, newly formed soils with little horizon development, found on steep rocky lands or floodplains.

Define municipal solid waste.

Discarded materials from households, businesses and institutions that are broken, spoiled or no longer useful.

Give two common methods of solid-waste disposal.

Sanitary landfilling and incineration.

What is source reduction in waste management?

Designing, manufacturing and using products to minimize the amount or toxicity of waste generated.

What fraction of Earth’s total water is freshwater?

About 2.5 %.

Which reservoir holds most of Earth’s liquid freshwater?

Groundwater (≈96 % of liquid fresh water).

Define residence time of water.

Average time a water molecule spends in a reservoir before moving to another part of the cycle.

What is thermohaline circulation in the oceans driven by?

Density differences caused by temperature (thermal) and salinity (haline) variations.

Differentiate marsh, swamp and estuary wetlands.

Marsh: shallow grassy wetland; Swamp: wooded wetland with low-oxygen water; Estuary: partly enclosed body where fresh river water meets seawater.

What causes a fluvial (riverine) flood?

Stream discharge exceeding channel capacity, causing overflow onto adjacent land.

Define an unconfined aquifer.

A permeable, water-bearing layer open to the surface; its water table rises and falls freely.

What is a flowing artesian well?

A well drilled into a confined aquifer where hydrostatic pressure makes water rise above ground level without pumping.

Explain losing vs. gaining streams.

Losing (influent) streams seep water into the ground, recharging aquifers; gaining (effluent) streams are fed by groundwater discharge.

State two human activities that degrade water quality.

Industrial pollution (acid mine drainage) and excessive agricultural fertilizer leading to eutrophication.

How does rainwater harvesting conserve water?

Collecting and storing rooftop rainwater in tanks for later domestic or agricultural use, reducing demand on groundwater.

What is the primary purpose of constructing dams?

To store and regulate river water for irrigation, hydropower, flood control and water supply.

Name the three oceanic layers based on temperature and density.

Surface layer (warm, mixed), Thermocline/transition zone, Deep zone (cold, dense).

What is salinity and its average value in open oceans?

Total dissolved salts in seawater; typically 33–37 ‰ (parts per thousand).

Describe permafrost.

Ground (soil or rock) that remains frozen for at least two consecutive years, often containing underground ice.

What is overland flow?

Water moving downslope across land during heavy rain before entering stream channels.

Define drainage basin (watershed).

Land area that collects precipitation and contributes runoff to a particular stream or river.

What marks the boundary between the zone of aeration and zone of saturation?

The water table.

List two key properties that make a rock a good aquifer.

High porosity (space to store water) and high permeability (interconnected pores for flow).

How can excessive dam construction negatively impact rivers?

It traps sediments, alters flow regimes and can reduce aquatic biodiversity.

Why is biomass considered renewable yet potentially problematic?

Plant matter can regrow, but burning it releases CO₂ and may compete with food production or cause deforestation.

Which mineral property is determined using a streak plate?

Streak – the color of the mineral’s powdered form.

What is cleavage in minerals?

Tendency to break along planes of weakness, producing smooth, flat surfaces.

Name two minerals identified by taste or smell.

Halite (salty taste) and sulfur‐bearing minerals (rotten-egg odor).

Explain secondary enrichment ore deposits.

Weathering leaches mobile elements, leaving enriched concentrations of valuable metals (e.g., supergene copper).

Why are lateritic soils rich in aluminum or nickel economically important?

Intense tropical weathering removes silica and concentrates insoluble oxides of aluminum (bauxite) or nickel (nickel laterite), forming economic ores.

What is the main environmental concern of burning fossil fuels?

Emission of CO₂ and other greenhouse gases leading to global warming and climate change.

Define capillary fringe in a groundwater profile.

Zone just above the water table where water rises into soil pores by capillary action.

How does topography influence soil thickness?

Steep slopes experience more erosion, resulting in thinner soils; gentle slopes allow thicker soil accumulation.

What is eutrophication and its primary cause?

Over-enrichment of water with nutrients (usually from fertilizer runoff), leading to algal blooms and oxygen depletion.

Give one advantage and one disadvantage of incineration for waste disposal.

Advantage: volume reduction and energy recovery; Disadvantage: air pollution requiring costly emission controls.

Which soil order is dominated by organic material and commonly water-logged?

Histosols.