List of time periods

From Free net encyclopedia

Template:Cleanup-date This is a list of named time periods defined in various fields of study.

Contents

Cosmological time periods

The cosmological timescale covers the entire lifetime of the universe - many billions of years - from it's formation (often called "the big bang") until it's termination (sometimes called "the big crunch"). The initial phases of the big bang are measured in tiny fractions of seconds but after these, cosmological events happen on a scale of billions of years; for example: our own sun is estimated to have a lifespan of 10 billion years. Cosmological time periods are used to think about events that occur on a universal scale such as: the formation stars, galaxies and the final fate of the universe.

Geologic time periods

Template:Mergeto

The geologic timescale covers the extent of the existence of Earth, from about 4600 million years ago to the present day. It is used to consider the formation and change of the Earth itself, and large-scale changes in the planet's inhabitants.

Dates are given as Millions of Years Ago (MYA).

Eon Era Period Epoch
Precambrian

(4600-544 MYA)

Hadean

(4600-3800 MYA)

Archaean

(3800-2500 MYA)

Proterozoic

(2500-544 MYA)

Phanerozoic

(544 MYA - now)

Paleozoic

(544-245 MYA)

Cambrian (544-505 MYA)
Ordovician (505-440 MYA)
Silurian (440-410 MYA)
Devonian (410-360 MYA)
Carboniferous

(360-286 MYA)

Mississippian (360-325 MYA)
Pennsylvanian (325-286 MYA)
Permian (286-245 MYA)
Mesozoic

(245-65 MYA)

Triassic (245-208 MYA)
Jurassic (208-146 MYA)
Cretaceous (146-65 MYA)
Cenozoic

(65 MYA - now)

Tertiary (65-1.8 MYA) Paleocene (65-54 MYA)
Eocene (54-38 MYA)
Oligocene (38-23 MYA)
Miocene (23-5 MYA)
Pliocene (5-1.8 MYA)
Quaternary (1.8 MYA - now) Pleistocene (1.8-0.01 MYA)
Holocene (0.01 MYA - now)


The Paleocene, the Eocene, and the Oligocene are also collectively known as the Paleogene. The Miocene, Pliocene, Pleistocene, and Holocene are also collectively known as the Neogene.

These names differ across different countries; in particular, the division of the Carboniferous period into Mississippian and Pennsylvanian is purely a North American distinction.

Human time periods

The "human" timescale covers the time that humans have existed, usually taken to be from about 250,000 years ago - when Homo Sapiens began to develop. It is broadly divided into prehistorical (before history began to be recorded) and historical periods (when written records began to be kept).

Calendar systems

Human historical periods

*: This date is somewhat subjective. Some sources cite 1937 as the start of World War II.

Mythological and astrological time periods


Specialist human periods

See also