Geologic Time Scale: Precambrian

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Neoproterozoic Era (1,000 to 538.8 million years ago), was the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods.

The Ediacaran Period is named after the Ediacara Hill of South Australia and marks the end of the Proterozoic Eon. The Ediacaran was ratified in 2004 by the International Union of Geological Sciences (IUGS) and is followed by the Cambrian Period of the Phanerozoic Eron. The Ediacaran is known for the first appearance of widespread multicellular fauna (Ediacaran biota) following the of Snowball Earth glaciation events.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Neoproterozoic Era (1,000 to 538.8 million years ago), was the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods.

The Cryogenian (from Ancient Greek meaning “cold” and “genesis”) Period was a time of drastic biosphere changes and was ratified in 1990 by the International Commission on Stratigraphy. Characteristic glacial deposits indicate that Earth suffered the most severe ice ages in its history during this period (Sturtian and Marinoan); a phenomenon which led to the hypothesis of deeply frozen planetary oceans called “Snowball Earth”

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Neoproterozoic Era (1,000 to 538.8 million years ago), was the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods.

The Totian ( from the Ancient Greek meaning “stretch”) is the first geologic period of the Neoproterozoic Era. Rifting leading to the breakup of supercontinent Rodinia, which had formed in the mid-Stenian, occurred during this period, starting 900 to 850 million years ago.

The first putative metazoan (animal) fossils are dated to the middle to late Tonian. The fossils of Otavia antiqua (discribed as a sponge by discoverers and numerous other scholars), dating back to 800 million years ago. Even earlier sponge-like fossils have been reported in reefs dating back to 890 million years ago.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Mesoproterozoic Era (1,600 to 1,000 million years ago), was the first era of Earth’s history for which a faily denitive geological recrd survives. Continents existed during the preceding Paleoproterozoic era, but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, althoug their arrangement on the Earth’s surface was different.

The Stenian Period (from Ancient Greek meaning “narrow”) is the final geologic period in the Mesoproterozoic Era. The supercontinent Rodinia assembled during the Stenian. It would lasr into the Tonian Period.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Mesoproterozoic Era (1,600 to 1,000 million years ago), was the first era of Earth’s history for which a faily denitive geological recrd survives. Continents existed during the preceding Paleoproterozoic era, but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, althoug their arrangement on the Earth’s surface was different.

The Ectasian Period (from Ancient Greek meaning “extension”) is the second geologic period in the Mesoproterozoic Era. This period is interesting for the first evidence of sexual reproduction. Microfossils of the multicellular filaments of Bangiomorpha pubescens (type of red algae-the first taxonomically resolved eukaryote) was the first organism that exhibited sexual reproduction, which is an essential feature for complex multicellularity.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Mesoproterozoic Era (1,600 to 1,000 million years ago), was the first era of Earth’s history for which a faily denitive geological recrd survives. Continents existed during the preceding Paleoproterozoic era, but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, althoug their arrangement on the Earth’s surface was different.

The Calymmian Period (from Ancient Greek meaning “cover”) is the first geologic period in the Mesoproterozoi Era. The period is characterised by exspansion of existing platforems (continental areas/masses). or by new platforms on recently cratonized basements. The supercontinent Columbia started to break during the Calymminan some 1,500 million years ago.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Paleoproterozoic Era (2,500 to 1,600 million years ago), (also spelled Paleoproterozoic) is the first of three subdivisions (eras) of the Proterozoic Eon. The Paleoproterozoic also the longest era of the Earth’s geological history.

The Satatherian Period (meaning “stable, firm”) is the final geologic period in the Paleoproterozoic Era. The period was characterized on most continents by either new platforms or final cratonization of folded mountain belts. Oxygen levels were 10% to 20% current values.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Paleoproterozoic Era (2,500 to 1,600 million years ago), (also spelled Paleoproterozoic) is the first of three subdivisions (eras) of the Proterozoic Eon. The Paleoproterozoic also the longest era of the Earth’s geological history.

The Orosirian Period (meaning “mountain range”) is the third geologic period in the Paleoproterozoic Era. Two of the largest known impact events on Earth occurred during the Orosirian at 2023 million years ago and later 1850 million years ago. The supercontinent Columbia formes at the end of this period.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Paleoproterozoic Era (2,500 to 1,600 million years ago), (also spelled Paleoproterozoic) is the first of three subdivisions (eras) of the Proterozoic Eon. The Paleoproterozoic also the longest era of the Earth’s geological history.

The Rhyacian Period (meaning “stream of lava”) is the second geologic period in the Paleoproterozoi Era. This is when the eukaryotes arethought to have originated from the symbiosis between asgardarchaea and alphaproteobacteria.

The Proterozoic (2,500 to 538.8 million years ago) is the most recent part of the Precambrian “super eon”. It is also the longest eon of the Earth’s geologic time scale.

Paleoproterozoic Era (2,500 to 1,600 million years ago), (also spelled Paleoproterozoic) is the first of three subdivisions (eras) of the Proterozoic Eon. The Paleoproterozoic also the longest era of the Earth’s geological history.

The Siderian Period (meaning “iron”) is the first geologic period in the Paleoproterozoic Era. The deposition of banded iron formations peaked early in this period. These iron, formations were formed as anerobic cyanobacteria produced waste oxygen that combined with iron, forming magnetite (Fe3O4 an iron oxide). This process removed iron from the Earth’s oceans, presumably turning greenish seas clear.

The Archean (or Archaean) Eon is the second of four Geologic Eons in Earth’s history. The Neoarchean (also spelled Neoarchaean) is the last geologic era in the Archean eon.

The era is marked by major developments in complex life and continental formation. The era saw the rise of oxygen in the atmosphere after oxygenic photosynthesis evolved as early as Mesoarchean era. 

The Archean (or Archaean) Eon is the second of four Geologic Eons in Earth’s history. The Mesarchean contains the first evidence of modern style plate subduction and expansion of microbial life.

Microbial life with diverse metabolisms expanded during the Mesoarchean era and produced gases that influenced early Earth’s atmospheric composition. Cyanobacteria produced oxygen gas, but oxygen did not begin to accumulate in the atmosphere until later in the Archean.

The Archean (or Archaean) Eon is the second of four Geologic Eons in Earth’s history. The Palaeoarchaean (formerly known as early Archean). The name derives from Greek “Palaios” meaning ancient.

Due to deformation and metamorphism, most rocks from the Paleoarchean Era cannot provide any useful information. The first photosynthetic organisms appeared.

The Archean (or Archaean) Eon is the second of four Geologic Eons in Earth’s history. The Eoarchean Era (Eoarchaean) is the first era of the Archeam Eon of the geologic record.

The Eoarchaean Era’s lower boundary or starting point of 4 Gya (4 billion years ago) is officially recognized by the international Commissin on Stratigraphy.

The beggining of the Eoarchean is characterized by heavy asteroid bombardment within the inner Solar System: the Late Heavy Bombartment.

The Hadean Eon is the begining of Earth’s history. The named derives from Hades, the Greek god of the underworld, and the underworld itself. The term was coined by American geologist Preston Cloud

Pre-Nectarian

(4,533 to 3,920 million years ago)

Formation of the Moon’s crust.