Precambrian – wikipedia natural gas in spanish

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Relatively little is known about the Precambrian, despite it making up roughly seven-eighths power outage houston reliant of the Earth’s history, and what is known has largely been discovered from the 1960s onwards. The Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from the Precambrian (e.g. stromatolites) are of limited biostratigraphic use. [2] This is because many Precambrian rocks have been heavily metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain deeply buried beneath Phanerozoic strata. [2] [3] [4]

It is thought that the Earth coalesced from material in orbit around the Sun at roughly 4,543 Ma, and may have been struck by a very large ( Mars-sized) planetesimal shortly after it formed, splitting off material that formed the Moon (see Giant impact gas bloating diarrhea hypothesis). A stable crust was apparently in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma. [5]

The term Precambrian is recognized d cypha electricity futures by the International Commission on Stratigraphy as the only supereon in geologic time; [ citation needed] it is so called because it includes the Hadean (~4.6—4 billion), Archean (4—2.5 billion), and Proterozoic (2.5 billion—541 million) eons. (There is only one other eon: the Phanerozoic, 541 million-present.) [6] Precambrian is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010 [update], the United States Geological Survey considers the term informal, lacking a stratigraphic rank. [7] Life forms [ edit ]

A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks (Archean eon) from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. [8] Probable fossils 100 million years older have been found in the same gas vs electric oven area. However, there is evidence that life could have evolved over 4.280 billion years ago. [9] [10] [11] [12] There is a fairly solid record of bacterial life throughout the remainder (Proterozoic eon) of the Precambrian.

Excluding a few contested reports gas constant for helium of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at roughly 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. [ citation needed] Fossil evidence from the later Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the gas and water middle of the following Cambrian period, a very diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa. The increase in diversity of lifeforms gas definition state of matter during the early Cambrian is called the Cambrian explosion of life. [13] [14]

Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, and that most of the Earth’s landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back gasket t 1995 as the Huronian epoch, roughly 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth.

At present, it is still believed that molecular oxygen was not a significant fraction of Earth’s atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism. This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis electricity in the body symptoms, sometimes called the oxygen catastrophe. At first, oxygen would have quickly combined with other elements in Earth’s crust, primarily iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere electricity units of measurement, and the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides.

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. The Precambrian could be divided into five natural eons, characterized as follows: [20]

The movement of Earth’s plates has caused the formation and break-up of continents over time, including occasional formation of a supercontinent containing most or all of the landmass. The earliest known electricity of the heart supercontinent was Vaalbara. It formed from proto-continents and was a supercontinent 3.636 billion years ago. Vaalbara broke up c. 2.845–2.803 Ga ago. The supercontinent Kenorland was formed c. 2.72 Ga ago and then broke sometime after 2.45–2.1 Ga into the proto-continent cratons called Laurentia, Baltica, Yilgarn craton, and Kalahari. The supercontinent Columbia or Nuna formed 2.06–1.82 billion years ago and broke up about 1.5–1.35 billion years ago. [21] [22] [ not in citation given] The supercontinent Rodinia is thought to have formed about 1.13–1.071 billion years ago, to have embodied most or all of Earth’s continents and to have broken up into eight continents around gas x directions 750–600 million years ago.