geologic time: Quick Facts

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Also Known As	geological time scale

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A detailed geologic time scale chart displaying Earth's history from the Hadean Eon over 4.5 billion years ago to the present, organized by eons, eras, periods, epochs, and ages with color-coded columns and corresponding dates in millions of years.

Vertical timeline illustration showing major events in Earth's history, from the planet's fiery formation and moon creation, through ancient rocks and early life such as blue-green algae, to the rise of atmospheric oxygen, ice ages, and the evolution of hard-shelled animals, dinosaurs, mammals, and humans, with labeled graphics and a geologic time scale on the right.

Cutaway diagram of a Grand Canyon wall showing layered sedimentary rocks-limestone, shale, sandstone, and composite rocks-with labels indicating Paleozoic rocks (about 252-541 million years old) above older Precambrian rocks, which include Proterozoic (541 million to 2.5 billion years old) and Archean (over 2.5 billion years old) layers. The Colorado River is shown at the base.

Line graph showing the number of marine animal families from the Precambrian era to the present, with illustrations of key groups such as trilobites, ammonoids, marine reptiles, and diatoms. The graph highlights major extinction events and a rise to 1,900 living families today.

A vertical geologic time scale chart spanning from 650 million years ago to the present, with colored bands for each era and period. Illustrations and labels highlight key evolutionary events such as the appearance of skeletal elements, first fishes, land plants, amphibians, reptiles, dinosaurs, mammals, and humans.

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Topics

period Precambrian geochronology A Journey Through Time Since the Precambrian Phanerozoic Eon Lipalian interval era How Old Is Earth?epoch eon Equator Climate geomagnetic field hydrosphere Atmosphere earthquake population gravity Biosphere continental landform

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