Geologic Time Scale and Earth Systems - Video Flashcards

A set of vocabulary-style flashcards covering key terms from geologic time, rock formation, metamorphism, Earth subsystems, and basic planetary concepts described in the video notes.

Geologic Time Scale

The calendar of Earth's history that divides its history into units (eons, eras, periods) to organize fossils, events, and changes over time.

Relative Time

Subdivision of Earth's history based on relative age relationships; rocks are arranged oldest at the bottom and youngest at the top.

Absolute Time

Measuring the actual age of rocks or events using physical attributes and radiometric dating for numerical ages.

Relative Dating

Determining the sequence of events by comparing rock layers and fossils using principles like Superposition, Original Horizontality, and Cross-Cutting Relationships.

Absolute Dating

Determining a specific age in years using methods such as Carbon-14 dating and Potassium-Argon dating.

Eon

The largest unit of geologic time; examples include Hadean, Archean, Proterozoic, and Phanerozoic.

Era

Second-largest time interval in the geologic scale; examples include Paleozoic, Mesozoic, and Cenozoic.

Hadean

Earliest geologic eon, preceding the formation of most rocks.

Archean

Geologic eon characterized by early crust formation and the beginnings of plate tectonics.

Proterozoic

Geologic eon between Archean and Phanerozoic; notable for continental growth and more complex life before the Phanerozoic.

Phanerozoic

Geologic eon marked by abundant fossil life and diverse organisms; contains the Paleozoic, Mesozoic, and Cenozoic.

Paleozoic

Era in the Phanerozoic dividing early animal life and major fossil records; ends with the Permian extinction.

Mesozoic

Era in the Phanerozoic known as the age of reptiles; ends with the Cretaceous-Paleogene extinction.

Cenozoic

Era in the Phanerozoic following the Mesozoic; age of mammals and birds.

Cambrian

First period of the Paleozoic; major diversification of life in the oceans.

Ordovician

Paleozoic period following the Cambrian with rich marine life; ends with a mass extinction.

Silurian

Paleozoic period following the Ordovician; early terrestrial plants appear.

Devonian

Paleozoic period known as the age of fishes; plants and terrestrial ecosystems expand.

Carboniferous

Paleozoic period known for coal-forming swamps and diverse life.

Permian

Late Paleozoic period ending with a major mass extinction.

Triassic

Early Mesozoic period; first dinosaurs appear and reefs develop.

Jurassic

Middle Mesozoic period known for large dinosaurs and diverse plant life.

Cretaceous

Late Mesozoic period; flowering plants arise and dinosaurs become extinct at the end.

Detrital sedimentary rocks

Sedimentary rocks derived from weathered preexisting rocks; examples include sandstone and shale.

Chemical sedimentary rocks

Sedimentary rocks formed from precipitation of soluble minerals; examples include flint and gypsum.

Lithification

Process of turning loose sediments into solid rock via compaction and cementation.

Compaction

Sediment layers are compressed by overlying materials, squeezing out fluids.

Cementation

Minerals precipitate from pore waters and bind sediment grains together.

Weathering

Breaking down or dissolving rocks and minerals by water, wind, ice, and biological activity.

Erosion

Removal and transport of weathered material by agents such as water, wind, and ice.

Deposition

Process by which sediment is laid down in a new location.

Delta

Triangular landform at a river mouth formed by sediment deposition.

Lithosphere

Rigid outer shell of Earth, including the crust and the upper mantle.

Atmosphere

Gaseous envelope surrounding Earth; major components include nitrogen and oxygen.

Troposphere

Lowest atmospheric layer where weather occurs.

Stratosphere

Layer containing the ozone layer; jet aircraft and weather balloons operate here.

Mesosphere

Layer that helps shield Earth from meteoroids; thick gases offer some protection.

Thermosphere

Hottest atmospheric layer; contains the ionosphere and is where the space shuttle orbits.

Exosphere

Outermost atmospheric layer; space environment and satellites reside here.

Hydrosphere

All of Earth's water, covering about 71% of the surface; most is salt water.

Biosphere

All living organisms and their interactions; the 'ozone of life' on Earth.

Goldilocks Zone

Star’s habitable zone where conditions allow liquid water to exist (not too hot, not too cold).

Terrestrial planets

Rocky planets with solid surfaces and cores (Mercury, Venus, Earth, Mars).

Jovian planets

Gas giants with thick atmospheres and no solid surfaces (Jupiter, Saturn, Uranus, Neptune).

Dwarf planets

Small planetary bodies that orbit the Sun but are not giant planets (e.g., Pluto, Ceres, Makemake, Haumea, Eris).

Habitable

Capable of supporting life given suitable environmental conditions.

Temperature range

Earthly life supports temperatures roughly between -15°C and 155°C.

Pressure

Atmospheric/planetary pressure and gravity needed to retain an atmosphere.

Sedimentary rocks

Rocks formed by deposition, compaction, and cementation of sediments.

Stratigraphy

Study of rock layers (strata) and their order of formation.

Superposition

In undisturbed strata, oldest rocks lie at the bottom and younger rocks above.

Original Horizontality

Sedimentary layers are originally deposited horizontally.

Cross-Cutting Relationships

Any feature that cuts through rocks is younger than the rocks it cuts.

Carbon-14 dating

Radiometric dating method for organic materials up to about 60,000 years old.

Potassium-Argon dating

Radiometric dating method for inorganic rocks, useful for older materials.

Igneous rocks

Rocks formed from cooling and solidification of molten magma or lava.

Extrusive (volcanic)

Igneous rocks that crystallize on or near the surface; typically fine-grained.

Intrusive (plutonic)

Igneous rocks that crystallize below the surface; typically coarse-grained.

Phaneritic

Coarse-grained igneous texture with visible crystals.

Aphanitic

Fine-grained igneous texture with crystals too small to see unaided.

Porphyritic

Igneous texture with larger crystals (phenocrysts) embedded in a fine-grained groundmass.

Obsidian

Glassy, non-crystalline volcanic rock formed by rapid cooling.

Felsic

Igneous rocks rich in silica and light-colored minerals like feldspar and quartz.

Mafic

Igneous rocks rich in magnesium and iron; typically dark-colored.

Andesitic

Igneous rocks with intermediate silica content and mixed light/dark minerals.

Ultramafic

Igneous rocks dominated by dark minerals rich in magnesium and iron (e.g., olivine).

Metamorphic rocks

Rocks changed by heat and pressure in solid state, without melting.

Contact metamorphism

Metamorphism due to heat from intruding magma, often producing non-foliated rocks.

Regional metamorphism

Widespread metamorphism due to high pressure and temperature during tectonic events, often foliated.

Foliated metamorphic rocks

Rocks with layered/banded texture from directed pressure (e.g., slate, phyllite, schist, gneiss).

Non-foliated metamorphic rocks

Rocks lacking layering; formed under uniform pressure (e.g., marble, quartzite, hornfels).

Slate

Fine-grained foliated metamorphic rock formed from shale.

Schist

Medium to coarse foliated metamorphic rock with visible mica.

Gneiss

Metamorphic rock with distinct light/dark mineral banding.

Migmatite

Partially melted metamorphic rock, transitional toward igneous.

Prograde metamorphism

Metamorphism with increasing temperature and pressure.

Retrograde metamorphism

Metamorphism with decreasing temperature and pressure.

Heat

A primary agent driving metamorphism by raising temperature.

Pressure

Confining or differential pressure driving mineral rearrangement during metamorphism.

Fluid phase

Intergranular spaces that may contain fluids; transport ions that facilitate metamorphic reactions.

Metasomatism

Chemical alteration of rocks due to fluid transport during metamorphism.