| Library / English Dictionary |
GEOLOGICAL PERIOD
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I. (noun)
Sense 1
Meaning:
A unit of geological time during which a system of rocks formed
Example:
ganoid fishes swarmed during the earlier geological periods
Synonyms:
geological period; period
Classified under:
Nouns denoting time and temporal relations
Hypernyms ("geological period" is a kind of...):
geologic time; geological time (the time of the physical formation and development of the earth (especially prior to human history))
Meronyms (parts of "geological period"):
epoch (a unit of geological time that is a subdivision of a period and is itself divided into ages)
Hyponyms (each of the following is a kind of "geological period"):
glacial epoch; glacial period; ice age (any period of time during which glaciers covered a large part of the earth's surface)
Instance hyponyms:
Age of Man; Quaternary; Quaternary period (last 2 million years)
Tertiary; Tertiary period (from 63 million to 2 million years ago)
Cretaceous; Cretaceous period (from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants)
Jurassic; Jurassic period (from 190 million to 135 million years ago; dinosaurs; conifers)
Triassic; Triassic period (from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity)
Permian; Permian period (from 280 million to 230 million years ago; reptiles)
Carboniferous; Carboniferous period (from 345 million to 280 million years ago)
Pennsylvanian; Pennsylvanian period; Upper Carboniferous; Upper Carboniferous period (from 310 million to 280 million years ago; warm climate; swampy land)
Lower Carboniferous; Lower Carboniferous period; Missippian period; Mississippian (from 345 million to 310 million years ago; increase of land areas; primitive ammonites; winged insects)
Age of Fishes; Devonian; Devonian period (from 405 million to 345 million years ago; preponderance of fishes and appearance of amphibians and ammonites)
Silurian; Silurian period (from 425 million to 405 million years ago; first air-breathing animals)
Ordovician; Ordovician period (from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds)
Cambrian; Cambrian period (from 544 million to about 500 million years ago; marine invertebrates)
Holonyms ("geological period" is a part of...):
era; geological era (a major division of geological time; an era is usually divided into two or more periods)
