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For the album by German band The Ocean, see Precambrian (album). The Ocean Collective (usually referred to as "The Ocean" is an experimental rock band from Berlin, Germany. Precambrian is the fifth studio album by the German Post-metal band The Ocean Collective, released on November 5 2007 through Metal Blade Records
Precambrian
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The Precambrian (Pre-Cambrian) is an informal name for the supereon comprising the eons of the geologic timescale that came before the current Phanerozoic eon. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Devonian is a geologic period and system of the Paleozoic era spanning from to  million years ago. The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 The Permian is a geologic period and system that extends from 299 The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago The Jurassic is a geologic period and system that extends from about Ma (million years ago to  Ma that is from the end of the Triassic to the beginning The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of The Paleogene (alternatively Palaeogene) is a geologic period and system that began 65 The Neogene is a geologic period and system starting 2303 ± 0 The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed It spans from the formation of Earth around 4500 Ma (million years ago) to the evolution of abundant macroscopic hard-shelled animals, which marked the beginning of the Cambrian, the first period of the first era of the Phanerozoic eon, some 542 Ma. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed It is named after the Roman name for Cymru/Wales - Cambria - where rocks from this age were first studied. Cambria is the classical name for Wales, being the Latinised form of the Welsh name Cymru (Wales

It is not an "era" - it is known simply as "Precambrian" [1]

Contents

Overview

Remarkably little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what little is known has largely been discovered in the past four or five decades. The history of Earth covers approximately 46 billion years (4567000000 years from Earth ’s formation out of the Solar nebula to the present The Precambrian fossil record is poor, and what fossils are present (such as those of stromatolites) are of limited use for biostratigraphic work. Stromatolites (from Greek στρώμα strōma, mattress bed stratum and λιθος lithos, rock are layered accretionary Structures formed in Biostratigraphy is the branch of Stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the Fossil assemblages contained [2] Many Precambrian rocks are heavily metamorphosed, obscuring their origins, while others have either been destroyed by erosion, or remain deeply buried beneath Phanerozoic strata. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed [3][4]

It is thought that the Earth itself coalesced from material in orbit around the sun roughly 4500 Ma and may have been struck by a very large (Mars-sized) planetesimal shortly after it formed, splitting off material that came together to form the Moon (see Giant impact theory). To help compare Orders of magnitude of different times this page lists times between 1017 seconds and 1018 seconds (3 Planetesimals are solid objects thought to exist in Protoplanetary disks and in Debris disks A widely accepted theory of planet formation the so-called planetesimal A stable crust was apparently in place by 4400 Ma, since zircon crystals from Western Australia have been dated at 4404 Ma. Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is Radiometric dating (often called radioactive dating) is a technique used to date materials usually based on a comparison between the observed abundance of a naturally occurring

The term Precambrian is somewhat dated, but is still in common use among geologists and paleontologists. A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. It was briefly also called the Cryptozoic eon. It seems likely that it will eventually be replaced by the preferred terms Proterozoic, Archaean, and Hadean, and become a deprecated term. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Hadean (ˈheɪdiən is the geologic eon before the Archean. (See geologic time scale. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other )

Life before the Cambrian

For more details on this topic, see Origin of life. In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic

It is not known when life originated, but carbon in 3800 million year old rocks from islands off western Greenland may be of organic origin. Well-preserved bacteria older than 3460 million years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area. There is a fairly solid record of bacterial life throughout the remainder of the Precambrian.

Excepting a few contested reports of much older forms from Texas and India, the first complex multicelled life forms seem to have appeared roughly 600 Ma. A quite diverse collection of soft-bodied forms is known from a variety of locations worldwide between 542 and 600 Ma. These are referred to as Ediacaran or Vendian biota. The Ediacara (ˌiːdɪˈækərə formerly Vendian) biota are ancient lifeforms of the Ediacaran Period which represent the earliest known complex Hard-shelled creatures appeared toward the end of that timespan.

A very diverse collection of forms appeared around 544 Ma, starting in the latest Precambrian with a poorly understood small shelly fauna and ending in the very early Cambrian with a very diverse, and quite modern Burgess fauna, the rapid radiation of forms called the Cambrian explosion of life. The small shelly fauna or small shelly fossils, abbreviated to SSF, are mineralized Fossils many only a few millimetres long with a nearly See also Burgess shale type fauna The Burgess Shale is famous for the exceptional preservation of the fossils found within it in which the soft parts are preserved The Cambrian explosion or Cambrian radiation was the seemingly rapid appearance of most major groups of complex Animals around, as evidenced by the

Planetary environment and the oxygen catastrophe

Details of plate motions and such are only hazily known in the Precambrian. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere It is generally believed that small proto-continents existed prior to 3000 Ma, and that most of the Earth's landmasses collected into a single supercontinent around 1000 Ma. In Geology, a supercontinent is a Landmass comprising more than one Continental core or Craton. The supercontinent, known as Rodinia, broke up around 600 Ma. For the Genus of Metalmark butterflies, see Rodinia (butterfly. A number of glacial periods have been identified going as far back as the Huronian epoch, roughly 2200 Ma. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. The Huronian Glaciation extended from 2400 mya to 2100 mya during the Siderian and Rhyacian periods of the Paleoproterozoic era The best studied is the Sturtian-Varangian glaciation, around 600 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth". The Cryogenian (from Greek cryos "cold" and genesis "birth" is a Geologic period that lasted from. The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of

The atmosphere of the early Earth is poorly known, but it is thought to have been smothered in reducing gases, containing very little free oxygen. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The young planet had a reddish tint, and its seas were thought to be olive green. Many materials with insoluble oxides appear to have been present in the oceans for hundreds of millions of years after the Earth's formation.

When evolving life forms developed photosynthesis, oxygen began to be produced in large quantities, causing an ecological crisis sometimes called the Oxygen Catastrophe. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. The Oxygen Catastrophe was a massive environmental change believed to have happened during the Siderian period at the beginning of the Paleoproterozoic The oxygen was immediately tied up in chemical reactions, primarily with iron, until the supply of oxidizable surfaces ran out. After that the modern high-oxygen atmosphere developed. Older rocks contain massive banded iron formations that were apparently laid down as iron and oxygen first combined. Banded iron formations (also known as banded ironstone formations or BIF s are a distinctive type of rock often found in primordial ( Precambrian) Sedimentary

Subdivisions

A diverse terminology has evolved covering the early years of the Earth's existence, but it is tending to settle out and come into greater use as radiometric dating allows plausible real dates to be assigned to specific formations and features. Radiometric dating (often called radioactive dating) is a technique used to date materials usually based on a comparison between the observed abundance of a naturally occurring The terms Archean (older than about 2500 Ma), Proterozoic (2500-600 Ma), and Neoproterozoic (600-542 Ma) appear to have general currency. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Neoproterozoic Era is the unit of geologic time from 1000 to 542 +/- 0 Some additional terms are included in the geological time line. See Timetable of the Precambrian. This is a timeline of geological and relevant astronomical events on Earth before the Cambrian period started

It has been proposed that the Precambrian should be divided into eons and eras that reflect stages of planetary evolution, rather than the current scheme based upon numerical ages. Such a system could rely on events in the stratigraphic record and be demarcated by GSSPs. A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for The Precambrian could be divided into five "natural" eons, characterized as follows. [5]

  1. Accretion and differentiation: a period of planetary formation until giant Moon-forming impact event.
  2. Hadean: the Late Heavy Bombardment period. The Late Heavy Bombardment (commonly referred to as the lunar cataclysm, or LHB) is a period of time approximately 3800 to 4100 million years ago ( mya
  3. Archean: a period defined by the first crustal formations (the Isua greenstone belt) until the deposition of banded iron formations due to increasing atmospheric oxygen content. The Isua greenstone belt is an Archean Greenstone belt in southwestern Greenland dated at 3 Banded iron formations (also known as banded ironstone formations or BIF s are a distinctive type of rock often found in primordial ( Precambrian) Sedimentary
  4. Transition: a period of continued iron banded formation until the first continental red beds. The term red beds usually refers to strata of reddish -colored sedimentary rocks such as Sandstone, Siltstone or Shale that
  5. Proterozoic: a period of modern plate tectonics until the first animals. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere

References

  1. ^ 5th-Grader Finds Mistake at Smithsonian
  2. ^ James Monroe and Reed Wicander, The Changing Earth, 2nd ed, (Belmont: Wadsworth Publishing Company, 1997), p. 492.
  3. ^ Monroe and Wicander, p. 492.
  4. ^ Pamela J.W. Gore, "The Precambrian". Retrieved on 12/6/06.
  5. ^ Bleeker, W. [2004]. "Toward a "natural" Precambrian time scale", in Felix M. Gradstein, James G. Ogg, and Alan G. Smith: A Geologic Time Scale 2004. Cambridge University Press. ISBN 0-521-78673-8.  

External links

Precambrian Phanerozoic  
(Hadean) Archean Proterozoic
The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed The Hadean (ˈheɪdiən is the geologic eon before the Archean. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth.

Dictionary

Precambrian

-adjective

  1. (informal) (geology) Relating to the eons before the Phanerozoic
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