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Topic: Precambrian


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In the News (Sun 16 Dec 18)

  
  Precambrian - Wikipedia, the free encyclopedia
The Precambrian is an informal name for the eons of the geologic timescale that came before the current Phanerozoic eon.
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 term Precambrian is somewhat dated, but is still in common use among geologists and paleontologists.
en.wikipedia.org /wiki/Precambrian   (910 words)

  
 Precambrian era. The Columbia Encyclopedia, Sixth Edition. 2001-05   (Site not responding. Last check: 2007-11-07)
Precambrian rocks are mostly covered by rock systems of more recent origin, but where visible they commonly display evidence of having been altered by intense metamorphism.
Precambrian rocks often occur in shields, which are large areas of relatively low elevation that form parts of continental masses.
The rocks of this region, and of the Early Precambrian as a whole, are generally granite, schist, or gneiss.
www.bartleby.com /65/pr/Precambr.html   (564 words)

  
 Precambrian Info - Encyclopedia WikiWhat.com
The Precambrian is the period of the geologic timescale from the appearance of Earth around 4.5 billion years ago (a billion being a thousand millions) to the evolution of abundant fossils, which marked the beginning of the Cambrian, some 540 million years ago.
It is thought that the Earth itself coalesced from material in orbit around the sun roughly 4500 million years before the present and may have been struck by a very large (Mars-sized) object shortly after it formed, splitting off material that came together to form the Moon.
A very diverse collection of forms appeared around 544 million years before the present 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".
www.wikiwhat.com /encyclopedia/p/pr/precambrian.html   (796 words)

  
 GeoFact No. 13, The Geology of Ohio--the Precambrian   (Site not responding. Last check: 2007-11-07)
Precambrian time (all of geologic time before the Cambrian Period) began when the Earth became a solid entity about 4.5 billion years ago and ended when the Cambrian Period began, about 570 million years ago.
Despite the immense span of time it represents, the Precambrian is the most poorly known of the geologic subdivisions in Ohio, in part because Precambrian rocks are nowhere exposed in the state.
Known Precambrian history of Ohio began with the emplacement of a vast, horizontal, 7-mile-thick layered sheet of granite (coarse-grained igneous rock formed at depth) and rhyolite (fine-grained volcanic equivalent of granite formed near the surface) beneath western Ohio and neighboring states to the west.
www.ohiodnr.com /geosurvey/geo_fact/geo_f13.htm   (1170 words)

  
 The Geology of Ohio--The Precambrian   (Site not responding. Last check: 2007-11-07)
Despite the immense span of time represented by these rocks, the Precambrian is the most poorly known of the geologic subdivisions in Ohio, in part because Precambrian rocks are nowhere exposed in the state.
Although wells that reached the Precambrian basement continued to be drilled at a slow but steady rate, little new understanding of the geologic history of the Precambrian geology of Ohio developed during nearly the next two decades.
Known Precambrian history of Ohio began with the emplacement of a vast, horizontal, 7-mile-thick layered sheet of granite and rhyolite beneath western Ohio and neighboring states to the west.
www.dnr.state.oh.us /geosurvey/oh_geol/96_winter/precambr.htm   (2871 words)

  
 Precambrian Era   (Site not responding. Last check: 2007-11-07)
The Precambrian was originally defined as the era that predated the emergence of life in the Cambrian Period.
The two major subdivisions of the last part of the Precambrian are the Archean (oldest) and the Proterozoic.
However, the Precambrian oceans did not settle in the basins we know, but covered much of the continents with shallow seas in which the story of a billion years of earth history was to be recorded.
www.geo.msu.edu /geo333/Precambrian.html   (2441 words)

  
 Search Results for Precambrian -¬†Encyclop√¶dia Britannica
Precambrian rocks were long ago defined to predate the Cambrian and therefore to predate all life, although the term Proterozoic was later coined from the Greek for “early life.” It is now known that...
Precambrian rocks constitute the oldest rocks of the continent and are preserved in the five core cratons.
The recorded history of the Precambrian, which covers more than 80 percent of the Earth's geologic history, is divided into two eons: the Archean, between roughly 3.8 and 2.5 billion years ago, and...
www.britannica.com /search?query=Precambrian&submit=Find&source=MWTEXT   (411 words)

  
 Precambrian HSU NHM
The Precambrian encompasses nearly 90% of the history of the Earth and around a third of the history of the Universe.
The Precambrian begins with the formation of the Solar System 4.57 billion years ago (bya) and extends to the beginning of the Cambrian 540 million years ago (Mya, or 0.54 bya).
Stromatolites are the dominant fossil type for most of the Precambrian, with the oldest identified examples going back at least 3450 million years.
www.humboldt.edu /~natmus/lifeThroughTime/PreCam.web   (3087 words)

  
 Precambrian fossils bibliography
Golovenok, V. K., 1982, On the Precambrian microbial remains in the Kirgitei Formation of the Yenisei Ridge [in Russian]: Doklady Akad.
Obruchev, S. V., 1958, Principles of Precambrian correlation in the Siberian Platform and the framing folded belts [in Russian], in Proceedings of Interdepartmental Conference on Elaboration of Unified Stratigraphic Schemes of Siberia: Leningrad, Izd.
Yankauskas, T. V., 1982, Upper Precambrian and Cambrian plant microfossils of the European USSR and their stratigraphic significance [in Russian] [Ph.D. dissert.]: University of Moscow, Moscow, 52 p.
www.talkorigins.org /origins/biblio/precambrian_fossils.html   (1607 words)

  
 Preliminary Precambrian Basement Map Showing Geologic-Geolphysical Domains-Wyoming.html
The Precambrian basement of Wyoming consists predominantly of the Archean Wyoming craton (province), and includes small parts of two Paleoproterozoic accreted orogens—the Trans-Hudson, on the east, and the Colorado, on the south.
However, the Precambrian basement is brought to the surface by a probable secondary, southwest-vergent thrust along the west face of the main mountainous area of the Bighorn Mountains; this thrust has a vertical displacement at the Precambrian surface of about 1,000 ft.
The basement blocks composed of Precambrian rocks were uplifted locally to high levels in the crust during the deformation, and subsequent erosion has molded the uplifted rocks into the present-day topography.
pubs.usgs.gov /of/2001/ofr-01-0199   (4542 words)

  
 Alibris: Precambrian
The authors explore the late Precambrian and earliest Cambrian fossil record to explain the Cambrian phenomenon and discuss the possibility of a major turnover in marine ecology at the beginning of the Cambrian period or whether a new, improved type of animal appeared at this time.
Precambrian Crustal Evolution of China the integrates theory of plate tectonics, structural geology and petrology to identify the tectonic and metamorphic environment in different stages of development of the Archaean and Proterozoic crust.
Further, the evolution of the Precambrian atmosphere and hydrosphere is approached by using geochemical data...
www.alibris.com /search/books/subject/Precambrian   (653 words)

  
 CVO Website - Precambrian   (Site not responding. Last check: 2007-11-07)
The earliest subdivision of the Precambrian, spanning the time between the formation of the Earth, about 4.5 billion years ago, and the start of the Archaean era, 3.8 billion years ago.
The middle era of Precambrian time, spanning the period between 3.8 and 2.5 billion years ago.
The final era of the Precambrian, spanning the time between 2.5 billion and 544 million years ago.
vulcan.wr.usgs.gov /LivingWith/VolcanicPast/Notes/precambrian.html   (189 words)

  
 Precambrian   (Site not responding. Last check: 2007-11-07)
However, the Precambrian does not contain abundant animal fossils, and cannot be subdivided as finely as the later Phanerozoic Eon.
Despite these limitations, studies of Precambrian geology and paleontology have helped us understand the origins and evolution of the continents, atmosphere, oceans, and life on Earth.
Precambrian and Early Paleozoic land surfaces were covered only by bacteria and algae, and large areas would have been bare rock.
geosrv01.bgsu.edu /Yacobucci/Geol_105/Outlines/Precambrian.htm   (3350 words)

  
 Chadwick, A. V. --- Precambrian Pollen in the Grand Canyon - A Reexamination
Creationists have often cited the presence of Precambrian pollen in the Grand Canyon as evidences against the validity of the geologic column.
The evidence that these Precambrian sediments were already hardened into stone before their uplift and erosion is clear: large angular fragments of indurated and fused quartz sand from the Precambrian Shinumo Formation (which overlies the Hakatai Formation) were incorporated into the Tapeats Sandstone.
Although there may not be evidence for Precambrian pollen in the Grand Canyon, there is one thoroughly documented report of the occurrence of pollen and vascular tissue of higher plants which does support the existence of angiosperms earlier in the fossil record.
www.grisda.org /origins/08007.htm   (2092 words)

  
 Precambrian Plant Fossils and the Hakatai Shale Controversy
Precambrian strata of much greater age than the Hakatai Shale are known to contain plant fossils.
The author proposes that Precambrian plant fossils exist, and reflect the effects of the global Flood on Antediluvian sediment and plant material.
It is age dated at approximately 1.25 Ga. Comparison of this Precambrian section to those of similar age found across other sections of the globe suggests that it is not out of the question to expect or find fossilized plant materials within the Hakatai Shale (Figure 2).
www.creationresearch.org /crsq/articles/36/36_3/plantfossils.html   (3746 words)

  
 Palaeos Timescale: The Precambrian
The Precambrian is sometimes referred to as an "eon." However, it actually has no rank.
The Precambrian is that stretch of geological time from the formation of the Earth itself to the start of the Cambrian period.
It was only at the very end of the Precambrian that there was a sort of "quantum leap" in evolution from simple microbes to complex multicellular organisms.
www.palaeos.com /Timescale/Precambrian.htm   (791 words)

  
 Precambrian Period   (Site not responding. Last check: 2007-11-07)
A lack of Precambrian rocks anywhere in the southern part of Nova Scotia is a significant difference between the southern and northern parts of the province.
The Precambrian Period was a time of great volcanic activity, but it is mostly shrouded in mystery.
The Precambrian rocks of Nova Scotia represent the remnants of volcanic islands adjacent to a deep sea trench.
museum.gov.ns.ca /fossils/geol/precamb.htm   (685 words)

  
 Precambrian Wholesale Limited   (Site not responding. Last check: 2007-11-07)
Precambrian Wholesale has been serving northern communities for over 27 years, specializing in groceries, electronics, hardware, sporting goods and home furnishings.
Precambrian Wholesale's corporate office and warehouse is located in Winnipeg, Manitoba, Canada.
Precambrian owns three subsidiary companies Frontier Foods, PWL Transport and Northern Burntwood.
www.precam.ca   (130 words)

  
 Precambrian Sedimentary Environments (SP 33) - Book Information
The motivation for this volume came from the idea that the Precambrian is the key, both to the present, and to the understanding of the Earth as a whole.
The introductory papers, written by experts on Precambrian environments, treat comprehensively the application of actualism to the Precambrian, the evolution and influence of life on the sedimentary rock record, the genesis of Banded Iron Formations, the Precambrian sulphur cycle and the significance of Precambrian chemical carbonate precipitates.
The contributions demonstrate that Precambrian sedimentary deposits are commonly similar to their Phanerozoic counterparts in terms of composition, sedimentary processes, and depositional setting, but may differ significantly as a result of lack of vegetation, climatic and biological constraints, composition and circulation of seawater, and the secular involvement of continental crust.
www.blackwellpublishing.com /book.asp?ref=0632064153   (806 words)

  
 A Creationist Exposed
There is a diagram there that says, "precambrian: void of fossils." That is a lie.
The precambrian is not void of fossils; the precambrian is extremely rich in fossils.
Because he said, first of all, you would not know, you could not establish whether these rocks were precambrian or cambrian...
www.talkorigins.org /faqs/gish-exposed.html   (1352 words)

  
 Precambrian Rocks in Colorado
With the largest exposure of Precambrian crystalline rocks in the western United States, Colorado is an outstanding place to study the rocks of this time period.
Nevertheless, observations elsewhere indicate that volcanic activity, mountain building, erosion and deposition of sedimentary rocks was widespread at the surface during these intrusive and metamorphic episodes.
For more information on Precambrian geology in Colorado, see the award winning book, Messages in Stone.
geosurvey.state.co.us /Default.aspx?tabid=290   (230 words)

  
 Nearctica - Paleontology - Precambrian and Origins of Life
Some of the topics covered are the three main subdivisions of the Precambrian, the early origins of life on earth, and the fossil record including the earliest known records of multicellular (metazoan) life.
An excellent synoptic introduction to the Precambrian with descriptions of the subdivisions of the early earth, the important events that occurred during this period, and the major fossil localities.
The Ediacaran fauna from the end of the Precambrian represents the first appearance of mulicelluar life in the fossil record.
www.nearctica.com /paleo/periods/precamb.htm   (239 words)

  
 Rock Strata of the Colorado Plateau: Formed by Noah's Flood?
Precambrian Pollen in the Grand Canyon - A Reexamination.
Considering the deep burial, lithification, and oxidized condition of the Hakatai shales, the state of preservation of these grains suggests that they were not a part of these sediments during their diagenesis.
Chadwick notes that "More difficulties are created than are solved by Burdick's report since it would require the explanation of the accumulation of all the Upper Precambrian sediments (10,000 ft.), their lithification and subsequent erosion before the first additional fossil forms were buried.
www.geocities.com /earthhistory/grand.htm   (3283 words)

  
 Precambrian Paleobiology
But it was during this Precambrian period when profound events occurred, leading ultimately to "life" as we know it today.
Stromatolitic structures span the Precambrian and extend to modern time, though they are currently limited to several isolated environments.
They have been attributed at least in part, because of the intense energy density of oxygen-burning aerobic metabolism of Eukaryotes, with the explosion of diversity in the late Precambrian into the Cambrian (the Cambrian Explosion).
www.fossilmuseum.net /Paleobiology/Preambrian_Paleobiology.htm   (1333 words)

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