Geologic History, Climate Change, and Earth Resources

Comprehensive vocabulary flashcards covering geologic time principles, climate dynamics, and the formation and extraction of Earth's energy and mineral resources.

Deep Time

The vastness of Earth's history, involving millions or billions of years, including the evolution of life and slow continuous planetary processes.

Geologic Timescale

The organizational system used by geologists to keep track of rocks, fossils, and environments throughout Earth's history.

Eons

Geologic time divisions representing approximately $\frac{1}{2}$ to $2$ billion years and major changes to Earth systems.

Hadean

The Eon representing Earth's formation.

Archean

The Eon during which microbes first emerged.

Proterozoic

The Eon characterized by an oxygen-rich atmosphere and the development of more complex life.

Phanerozoic

The Eon marked by an explosion in the evolution and diversity of life.

Superposition

The principle that in an undisturbed sequence of sedimentary rock, layers below were created before the layers above.

Lateral Continuity

The principle that layers are deposited over wide areas and are continuous in all directions unless removed by erosion.

Original Horizontality

The principle stating that layers of sediment are generally deposited in a horizontal position and remain flat until disturbed by tectonic forces.

Cross-Cutting Relationships

The principle that rock layers or features that are cut (such as by a fault or intrusion) are older than the feature that cuts them.

Unconformity

A contact between rock layers that represents a gap in time due to periods of no deposition or significant erosion.

Disconformity

A specific type of unconformity that occurs when erosion interrupts a sequence of sedimentary layers.

Nonconformity

The contact between older igneous or metamorphic foundation rock and younger sedimentary layers.

Angular Unconformity

An unconformity where flat-lying sedimentary rocks are deposited on top of older tilted or folded layers.

Half-life

The amount of time required for $\frac{1}{2}$ of the parent radioactive isotopes in a mineral to decay into daughter atoms.

Zircon ($ZrSiO_4$)

A hard igneous mineral used in radiometric dating because Uranium isotopes can substitute for Zirconium in its lattice.

Weather

Daily or weekly conditions for a specific location, such as current temperature or precipitation.

Climate

The average variation of conditions like temperature and humidity across a region over a long period of time.

Milankovitch Cycles

Three types of changes in Earth's orbit (Precession, Tilt, and Eccentricity) that occur over thousands of years and affect the amount of solar energy received.

Ice Age

A period in Earth's history where ice exists at the poles; temperatures are typically $11^{\circ}F$ colder than present.

Glacial Period

A time during an ice age when large glaciers cover significant portions of the continents.

Interglacial Period

A warmer period within an ice age, such as the current era, where glaciers have retreated.

Peat

Organic matter buried in oxygen-poor swamp water that serves as the raw material for coal formation.

Anthracite

The highest purity grade of coal, containing >85\% carbon and the lowest water content.

Kerogen

The organic material produced from buried plankton in oxygen-poor ocean water, which eventually transforms into oil and gas.

Source Rocks

Kerogen-rich layers of rock that produce oil and natural gas when subjected to heat and pressure.

Reservoir Rocks

Permeable rock layers where oil and gas accumulate by filling the gaps between sediment grains.

Caprock

A layer of rock that lacks space between grains, blocking the upward flow of oil and gas.

Hydraulic Fracturing (Fracking)

The process of pumping water, sand, or gas into pipes at high pressure to fracture source rock and release oil and gas.

Ore

A rock that contains a high enough concentration of an economically useful element or mineral to be mined for profit.

Banded Iron Formations

Sedimentary ores composed of $50\%$ iron oxide, formed by slow chemical reactions in cold temperatures.

Placer Mining

A mining method where dense metals like gold are collected from river beds after being eroded from rock layers by nature.

Open Pit Mining

An extraction method used when it is most cost-effective to dig out and process large volumes of rock to retrieve valuable elements.

Geoengineering

Techniques such as Solar Radiation Management that attempt to disrupt climate patterns by reflecting sunlight back into space using aerosols.