Earth Systems, Geology, Atmosphere, and Stellar Evolution

Flashcards covering Earth's spheres, crust layers and minerals, the rock cycle, gold mining, atmospheric layers and density, the greenhouse effect, and the life cycle of stars.

What is the lithosphere composed of?

Earth's crust and upper mantle, which includes rock, soil, minerals, mountains, and the seafloor.

How is the hydrosphere described in terms of composition?

It encompasses all water in every form; it is mostly salty ocean, while a small fraction is fresh.

What gases constitute the atmosphere and where is air densest?

It consists mostly of nitrogen and oxygen, with trace gases being the least abundant. Air is densest near the ground.

What defines the biosphere?

All living things and their interactions with rock, soil, air, and water, with nearly all life located in a narrow zone close to Earth's surface.

What are the characteristics of Earth's crust?

It is the thinnest layer, made of solid rock and soil, and includes land and the seafloor.

What state of matter is the mantle in near the core versus in the upper mantle?

Rock near the core melts into slow-flowing magma, while the upper mantle is solid.

What is Earth's core primarily composed of, and what are the states of the outer and inner core?

The core is mostly iron; the outer core is liquid, while the inner core is solid and the hottest layer.

Which eight elements commonly make up minerals in Earth's crust?

Oxygen, silicon, aluminium, iron, calcium, sodium, potassium, and magnesium.

How do igneous rocks form depending on where magma cools?

They form from cooling magma, with slow cooling occurring underground and fast cooling occurring at the surface.

How do sedimentary rocks form?

They form from weathered rock fragments that are deposited in layers and compressed.

How do metamorphic rocks form and what structure does repeated heating produce?

Heat alters the chemical structure of existing rock, and repeated heating creates mineral bands.

How does gold form and deposit within Earth's crust?

Gold forms deep in Earth's crust and molten rock pushes it upward to fill cracks, forming veins or reefs; erosion later carries it away and its high density causes heavy particles to settle into rich sediment deposits.

What physical extraction methods are used to recover dense gold from river sediments?

Panning and sluicing, which use gravity to separate dense gold from sediments.

What are the primary economic benefits and environmental harms of South African mining?

It boosts the economy, builds infrastructure, and creates jobs from rich deposits of gold and platinum, but it destroys habitats, scars land, pollutes water and air, and releases dust and toxic waste.

What percentage of the atmosphere is made up of the two main gases, and what happens to air density with height?

The two main gases make up $99\%$ of the atmosphere in fixed proportions; air density falls with height as gas particles thin out until the atmosphere merges with space.

What occurs in the troposphere?

It is the layer closest to Earth where clouds and the water cycle occur, temperature drops with altitude, and most living things live.

What is the function of the ozone layer in the stratosphere, and what are the effects of excess UV radiation?

The ozone layer absorbs harmful UV radiation to shield life and warm the layer; excess UV causes sunburn, skin cancer, eye damage, and harms plant photosynthesis.

What phenomena occur in the mesosphere?

It has very cold and thin air where meteors burn up (seen as shooting stars), and temperature drops higher up.

What are the key characteristics of the thermosphere?

It absorbs UV rays and X-rays from the Sun to protect life, reflects radio waves, and has gas particles that reach very high temperatures.

How does the greenhouse effect work and what are the main greenhouse gases listed?

Sunlight warms Earth's surface and the ground radiates heat back, which is trapped by gases to keep Earth warm enough for life; the main gases are carbon, water vapour, and methane.

How does a star begin to form inside a nebula?

Gravity pulls part of a large cloud composed mostly of hydrogen and helium inward to form a hot protostar.

What process marks the birth of a star?

The ignition of hydrogen fusion, which turns hydrogen into helium and releases massive amounts of energy.

What occurs during the stable main-sequence phase of a star's life?

Nuclear fusion balances gravity.

How is the Sun classified, and at what stage of life is it currently?

It is a medium yellow dwarf that is halfway through its life.

What sequence of events happens when a star runs out of hydrogen fuel?

Fusion weakens, the star heats up and swells into a giant, and then it blows away its outer gas to form a planetary nebula.

What remains of a star after its outer gas forms a planetary nebula?

A leftover core where fusion stops, which becomes a dense, hot white dwarf that slowly cools over time.

Rock cycle

The natural, continuous process in which rocks form, are broken down and re-form over long periods of time.

Granite

An igneous rock formed from a large mass of magma that cooled slowly deep inside Earth.

Pumice stone

An igneous rock that formed as magma emerged and cooled quickly on the surface of Earth.

Concentric

Having the same centre as something else.

Section drawing

A drawing that shows what something would look like if cut in half.

Magma

Rock that is so hot it has melted.

Element

A material that consists of atoms of only one kind.

Compound

A material that consists of atoms of two or more different elements chemically bonded together.

Minerals

Elements or compounds of elements that occur naturally in Earth's crust.

Extract

Remove or take out of.

Veins (geology)

Thin lines of solidified lava that have formed in cracks in other rock.

Ore

Rock with a high concentration of a valuable mineral.

Mining

The process by which the ore is removed from the crust.

Physical extraction process

Using physical methods to extract minerals from ore or sediment.

Alluvial

Material deposited by a river.

Sediment

Small particles like sand, mud, stones or pebbles that have been deposited somewhere.

Chemical extraction process

The use of chemicals to extract minerals from ore.

Refining

Making a natural product pure by removing unwanted substances.

Spheres of Earth

One of four interacting parts of Earth.

Density

The amount of mass in a given volume of a material.

Altitude

Height above sea level.

Temperature gradient

How much temperature changes with altitude.

Greenhouse gases

Gases that absorb Earth's outgoing energy, trapping it in the atmosphere.

Global warming

An increase in the average temperature of the atmosphere.

Climate change

Long term changes in Earth's temperature and precipitation patterns.

Mass extinction

The extinction of one or more species in a short period of time.

Extinct

When a species dies out completely and there are no living members left.

Stellar evolution

The birth, life and death of stars.

Gravitational contraction

Process whereby a nebula's gravity overcomes its internal pressure, causing a collapse.

Kelvin

Temperature scale used in science where the unit is kelvin ($\text{K}$), and a $1\,\text{K}$ difference in temperature is the same as a $1\,^\circ\text{C}$ difference.

Solar mass

Standard unit of mass in astronomy, equal to the mass of the Sun.

Magnetic field

Region around magnetic material, or a moving electric charge, where the force of magnetism acts.

Igneous rocks

Rocks that form when magma cools down.

Metamorphic rocks

Rocks that form when the chemical structure of existing rocks is changed by heat.

Sedimentary rocks

Rocks that form from particles of rock deposited in layers.

Crust

The outermost layer of Earth.

Mantle

The layer of Earth between the outer core and the crust.

Outer core

The liquid layer of Earth surrounding the inner core.

Inner core

The innermost solid layer of Earth.

Lithosphere

The part of Earth made up of soil and solid rock; the crust and outer layer of the mantle.

Atmosphere

The mixture of gases held round Earth by gravity.

Hydrosphere

The sphere of Earth that consists of water in all its forms.

Biosphere

The sphere of Earth that consists of all living things and their interactions with the rocks, soil, air and water of Earth.

Troposphere

The lowest layer of the atmosphere, closest to the surface of Earth.

Stratosphere

The second layer of the atmosphere from Earth's surface.

Mesosphere

The third layer of the atmosphere from Earth's surface.

Thermosphere

The fourth layer of the atmosphere from Earth's surface and the one furthest from it.

Greenhouse effect

A warming effect caused by the trapping of energy in the atmosphere.

Nuclear fusion

Process in which atoms combine to create larger atoms and massive amounts of energy.