geological period

1. is a type of: geologic time, geological time - the time of the physical formation and development of the earth (especially prior to human history)
   subtypes: glacial epoch, glacial period, ice age - any period of time during which glaciers covered a large part of the earth's surface
   specific instances:

   • 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
   has: epoch - a unit of geological time that is a subdivision of a period and is itself divided into ages
   is a part of: era, geological era - a major division of geological time; an era is usually divided into two or more periods
   same as: period

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