geological timescale
Eons, eras, periods
The geological timescale is the system scientists use to divide Earth's 4.5-billion-year history into named intervals based on rock layers and fossil records.
Major divisions include eons, eras, periods, and epochs—terms like Jurassic, Cretaceous, and Holocene.
On a geological timescale, human civilization is barely a blip.
Large-scale species elimination
- Cambrian explosionSudden appearance of complex life
- oxygenationAdding breathable gas
- glaciationIce sheet spreading process
- PangaeaPrehistoric unified landmass
continental drift · plate tectonics · volcanism · asteroid impact · K-Pg boundary · Permian extinction · rifting · orogeny
Study of geological ages
- stratigraphyStudy of rock layers
- radiometricMeasuring by radiation
- isotopeElemental variant by mass
- carbon-14Radioactive isotope for dating
uranium-lead · potassium-argon · relative · absolute · half-life · decay · correlation · superposition
Immense time division
- eraDistinct historical period
- periodPunctuation ending sentences
- epochDistinct historical period
- ageDuration of existence
Precambrian · Paleozoic · Mesozoic · Cenozoic · Archean · Proterozoic · Cambrian · Ordovician
Thousand million revolutions around sun
- million yearsOne thousand millennia
- MaMillion years ago
- antiquityGreat age, ancient era
- prehistoryEra before writing
planetary formation · abiogenesis · Anthropocene · uniformitarianism · catastrophism · immensity · vastness
Preserved ancient organism
- trilobiteExtinct segmented marine arthropod
- dinosaurExtinct Mesozoic reptile
- ammoniteExtinct spiral-shelled cephalopod
- archaeopteryxEarly feathered dinosaur genus
brachiopod · petrification · paleobotany · megafauna · extinction · biodiversity · fauna · flora
Formed from deposited material
- layersStacked levels or coatings
- formationCreation or arrangement
- bedrockSolid stone underground
- outcropSurfacing native stone
deposition · sedimentation · facies · sequence · unconformity · limestone · shale · sandstone
mass extinction
Large-scale species elimination
- Cambrian explosionSudden appearance of complex life
- oxygenationAdding breathable gas
- glaciationIce sheet spreading process
Pangaea · continental drift · plate tectonics · volcanism · asteroid impact · K-Pg boundary · Permian extinction · rifting · orogeny
geochronology
Study of geological ages
- stratigraphyStudy of rock layers
- radiometricMeasuring by radiation
- isotopeElemental variant by mass
carbon-14 · uranium-lead · potassium-argon · relative · absolute · half-life · decay · correlation · superposition · cross-cutting
eon
Immense time division
age · Precambrian · Paleozoic · Mesozoic · Cenozoic · Archean · Proterozoic · Cambrian · Ordovician · Silurian
billion years
Thousand million revolutions around sun
- million yearsOne thousand millennia
- MaMillion years ago
- antiquityGreat age, ancient era
prehistory · planetary formation · abiogenesis · Anthropocene · uniformitarianism · catastrophism · immensity · vastness
fossil
Preserved ancient organism
- trilobiteExtinct segmented marine arthropod
- dinosaurExtinct Mesozoic reptile
- ammoniteExtinct spiral-shelled cephalopod
archaeopteryx · brachiopod · petrification · paleobotany · megafauna · extinction · biodiversity · fauna · flora · coprolite
sedimentary
Formed from deposited material
outcrop · deposition · sedimentation · facies · sequence · unconformity · limestone · shale · sandstone · mudstone
geological, timescale, geology, geologic, geologist, geologists, geologically, geo, time