the time of the physical formation and development of the earth (especially prior to human history)

last 2 million years

from 63 million to 2 million years ago

from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants

from 190 million to 135 million years ago; dinosaurs; conifers

from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity

a major division of geological time; an era is usually divided into two or more periods

a unit of geological time that is a subdivision of a period and is itself divided into ages

any period of time during which glaciers covered a large part of the earth's surface

a period of lower temperatures during an interglacial separating the glacial periods of an ice age.

the first geologic period in the Paleoproterozoic Era that lasted from 2500 to 2300 million years ago.

The Rhyacian is the second geologic period in the Paleoproterozoic Era and lasted from 2300 to 2050 million years ago.

The Orosirian is the third geologic period in the Paleoproterozoic Era and lasted from 2050 to 1800 million years ago.

last 2 million years

from 63 million to 2 million years ago

from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants

from 190 million to 135 million years ago; dinosaurs; conifers

from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity

a major division of geological time; an era is usually divided into two or more periods

a unit of geological time that is a subdivision of a period and is itself divided into ages