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Era
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Period or System
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Epoch or Series
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Cenozoic
(65 million years ago - Present)
"Age of Recent Life"
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An era of
geologic time from the beginning of the Tertiary period to the present. Its
name is from Greek and means "new life."
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Quaternary
(1.8 million years ago - Present)
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The second
period of the Cenozoic era. It contains two epochs: the Pleistocene and the
Holocene. It is named after the Latin word "quatern" (four at a
time).
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The several
geologic eras were originally named Primary, Secondary, Tertiary, and
Quaternary. The first two names are no longer used. Tertiary and Quaternary
have been retained but used as period designations.
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Holocene
(8,000 years ago - Present)
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An epoch
of the Quaternary period. It is named after the Greek words
"holos" (entire) and "ceno" (new).
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Pleistocene
(1.8 million - 8,000 years ago)
"The Great Ice Age"
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An epoch of
the Quaternary period. It is named after the Greek words "pleistos"
(most) and "ceno" (new).
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Tertiary
(65 - 1.8 million years ago)
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The first
period of the Cenozoic era (after the Mesozoic era and before the
Quaternary period).
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Pliocene
(5.3 - 1.8 million years ago)
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Final epoch of the
Tertiary period. It is named after the Greek words "pleion"
(more) and "ceno" (new).
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Miocene
(23.8 - 5.3 million years ago)
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A epoch
of the upper Tertiary period. It is named after the Greek words
"meion" (less) and "ceno" (new).
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Oligocene
(33.7 - 23.8 million years ago)
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An epoch of
the early Tertiary period. It is named after the Greek words
"oligos" (little, few) and "ceno" (new).
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Eocene
(55.5 - 33.7 million years ago)
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An epoch of the
lower Tertiary period. Its name is from the Greek words "eos"
(dawn) and "ceno" (new).
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Paleocene
(65 - 55.5 million years ago)
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Earliest
epoch of the Tertiary period. It is named after the Greek words
"palaois" (old) and "ceno" (new).
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Mesozoic
(248 - 65 million years ago)
"Age of Medieval Life"
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An era of
geologic time between the Paleozoic and the Cenozoic. The word Mesozoic is
from Greek and means "middle life."
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Cretaceous
(145 - 65 million years ago)
"The Age of Dinosaurs"
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The final
period of the Mesozoic era. The name is derived from the Latin word for
chalk ("creta") and was first applied to extensive deposits of
this age that form white cliffs along the English Channel between Great
Britain and France.
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Late or Upper
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Early or Lower
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Jurassic
(213 - 145 million years ago)
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The middle
period of the Mesozoic era. It is named after the Jura Mountains between
France and Switzerland, where rocks of this age were first studied.
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Late or Upper
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Middle
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Early or Lower
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Triassic
(248 - 213 million years ago)
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The earliest
period of the Mesozoic era. The name Triassic refers to the threefold
division of rocks of this age in Germany.
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Late or Upper
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Middle
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Early or Lower
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Paleozoic
(544 - 248 million years ago)
"Age of Ancient Life"
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An era of
geologic time, from the end of the Precambrian to the beginning of the
Mesozoic. The word Paleozoic is from Greek and means "old life."
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Permian
(286 - 248 million years ago)
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The final
period of the Paleozoic era. It is named after the province of Perm,
Russia, where rocks of this age were first studied.
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Late or Upper
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Middle
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Carboniferous
(360 - 286 million years ago)
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A period of
time in the Paleozoic era that includes the Pennsylvanian and Mississippian
periods.
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Pennsylvanian*
(325 - 286 million years ago)
"The Coal Age"
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A period of
the Paleozoic era. It is named after the state of Pennsylvania where rocks
of this age are widespread.
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Late or Upper
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Middle
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Early or Lower
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Mississippian*
(360 - 325 million years ago)
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A period
of the Paleozoic era. It is named after the Mississippi River valley, which
contains good exposures of rocks of this age.
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Late or Upper
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Early or Lower
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Devonian
(410 - 360 million years ago)
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A period of
the Paleozoic era. It is named after Devonshire, England, where rocks of
this age were first studied.
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Late or Upper
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Middle
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Early or Lower
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Silurian
(440 - 410 million years ago)
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A
period of the Paleozoic. It is named after a Celtic tribe called the
Silures.
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Late or Upper
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Middle
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Early or Lower
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Ordovician
(505 - 440 million years ago)
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The second
earliest period of the Paleozoic era. It is named after a Celtic tribe
called the Ordovices.
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Late or Upper
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Middle
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Early or Lower
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Cambrian
(544 - 505 million years ago)
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The
earliest period of the Paleozoic era. It is named after Cambria, the Roman
name for Wales, where rocks of this age were first studied.
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Late or Upper
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Middle
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Early or Lower
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Precambrian
(Beginning of earth - 544 million years ago)
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All
geologic time before the beginning of the Paleozoic era. This includes
about 90% of all geologic time and spans the time from the beginning of the
earth, about 4.5 billion years ago, to 544 million years ago. Its name
means "before Cambrian."
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