Geologic Time Scale Terms – Flashcards
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Geologic Time Scale
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A record of the geologic events in Earth's history. Divided into Era's, Period's, and Epoch's.
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Precambrian
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The time in the earths early geological history before life started to evolve. It accounts for ninety percent of earth's geological history.
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Eras
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The 3 major eras of geologic time between the Precambrian period and the present. Paleozoic Era Mesozoic Era Cenozoic Era Mass extinctions mark boundaries between eras.
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Periods
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On the Geologic Time Scale, "Era" are subdivided into Periods; example: Mesozoic Era is subdivided into the Triassic, Jurassic and Cretaceous Periods.
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Epoch
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A distinct period of geological time. In the present time we live in the Holocene epoch, of the Quaternary period, of the Cenozoic era.
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Paleozoic Era
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Abundant life first appears in ocean The earliest of the 3 geological eras, it 540 - 245 million years ago.
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Mesozoic Era
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Age of reptiles 250 million to 65 million years ago. Also known as the Greatest Killing as the era ended with the extinction of the dinosaurs.
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Permian period
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Greatest extinction in history Paleozoic era from 251 million years
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Pennsylvanian period
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Paleozoic Era 318 million years ago a period of massive glacier activity.
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Mississippian period
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Paleozoic era 359 million years ago in North America, period known primarily for formation of marine limestones
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Devonian period
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Paleozoic era 416 million years ago Free-sporing vascular plants began to spread across dry land, forming extensive forests
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Silurian period
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First life on land Paleozoic Era 444 million years ago.
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Ordovician period
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First vertebrates develop Paleozoic era 488 million years ago.
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Cambrian period
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Paleozoic era 542 million years marked with great increase in diversity of multicellular life.
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Cretaceous period
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Mesozoic era 145 million years ago
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Jurassic period
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Mesozoic era 200 million years ago also known as the age of dinosaurs.
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Triassic period
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Mesozoic era 251 million years ago Both the start and end of the period are marked by major extinction events.
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Cenozoic Era
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Age of mammals The present period of geologic time, beginning 65 million years ago.
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Earth history
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4.5 billion years ago
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First life on earth
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3.5 billion years ago
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Ice age
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Pleistocene epoch
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Correlation
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Establishing equivalence Time equivalences Material equivalences
