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Topic: Stromatolite


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  Stromatolite - Wikipedia, the free encyclopedia
Stromatolites are commonly thought to have been formed by the trapping, binding, and cementation of sedimentary grains by microorganisms, especially cyanobacteria.
Stromatolites in the geological record declined sharply in both diversity and number during the Paleozoic, and are uncommon in modern day marine environments.
The domal morphology of biological stromatolites is the result of the vertical growth necessary for the continued infiltration of sunlight to the organisms for photosynthesis.
en.wikipedia.org /wiki/Stromatolite   (458 words)

  
 Stromatolites
In many respects stromatolites are the most intriguing fossils that are our singular visual portal (except for phylogenetic determination of conserved nucleic acid sequences and molecular fossils) into deep time on earth, the emergence of life, and the eventual evolving of the beautiful life forms from Cambrian to modern time.
Stromatolites and their close cousins the thrombolites, are rock-like buildups of microbial mats that form in limestone- or dolostone-forming environments.
By normalizing stromatolite forms with volume of preserved carbonate rock, the authors posit that the steepest decline in stromatolite form diversity occured in the late Neoproterozoic, and culminated in the Lower Cambrian, coincident with the widespread appearance of macroscopic metazoa and significant bioturbation (i.e., activity of bottom-living animals that keeps sediments oxygenated and homogenous).
www.fossilmall.com /Science/About_Stromatolite.htm   (2119 words)

  
 Stromatolites - Fossils - Rocks & minerals: Minnesota DNR
Cross section of a stromatolite from the Peter Mitchell Mine, Minnesota.
Stromatolites, colonial structures created by cyanobacteria (commonly called blue-green algae) are among the oldest fossils on earth, being found in rocks over 3 billion years old.
In Minnesota, stromatolites most commonly occur in the Biwabik Iron formation, the rocks of which have been mined for iron for over 100 years.
www.dnr.state.mn.us /fossils/stromatolites.html   (213 words)

  
 Encyclopedia: Stromatolite   (Site not responding. Last check: 2007-10-08)
Stromatolites are almost unique in that their fossil forms were found before living ones were discovered.
The stromatolites that are living today usually are located in areas where the water is so salty that snails and other predators can't survive.
Stromatolites are thought to have been common from 3.5 billion years ago until multicelled animal predators became common about 600 million years ago.
www.nationmaster.com /encyclopedia/Stromatolite   (1080 words)

  
 Stromatolite   (Site not responding. Last check: 2007-10-08)
Stromatolites are domal structures formed by the fossilized remains of cyanobacteria.
The domal morphology of stromatolites is the result of the vertical growth necessary for thecontinued infiltration of sunlight to the organisms for photosynthesis.
Stromatolite fossils are found mostly inhypersaline lagoons in warm climates such as that of WesternAustralia where excellent examples are found at Shark Bay.
www.therfcc.org /stromatolite-161427.html   (226 words)

  
 Stromatolite Info - Bored Net - Boredom   (Site not responding. Last check: 2007-10-08)
Stromatolites are carbonate rich layered structures built up by bacteria.
Stromatolites are common as fossils and are found in rocks up to several thousand million years old.
The oldest known probable stromatolite fossils are so called "egg carton" structures from western Australia thought to be about 3.5 billion years old.
www.borednet.com /e/n/encyclopedia/s/st/stromatolite.html   (94 words)

  
 Welcome to the Astrobiology Institute   (Site not responding. Last check: 2007-10-08)
Stromatolites, formerly defined as: "laminated organo-sedimentary structures formed by the trapping and binding, and/or precipitation of minerals by microorganisms", can be thought of as microbial mats in which a rock-like layer of either sand or precipitated minerals is also present.
This is a vertical cross section of a stromatolite that was constructed by cyanobacteria and green algae in a continental, alkaline lake.
Stromatolites still grow today in alkaline and saline lakes where the adverse chemistry of the lake waters have suppressed the populations of algae and grazing animals.
nai.arc.nasa.gov /students/this_month/page2.cfm   (446 words)

  
 Stromatolites   (Site not responding. Last check: 2007-10-08)
Stromatolite heads are scattered in carbonate mud in the center of the exposure.
Stromatolite heads up to 2 feet across are juxtaposed to each other on three sides of the exposure.
Stromatolites are forming today in the hyper-saline waters of Hamelin Pool at the base of Shark Bay, Western Australia.
student1www.fullcoll.edu /00029861/stromatolites.html   (105 words)

  
 Untitled Document
The only known examples of stromatolites presently forming in open marine environments of normal seawater salinity are on the margins of Exuma Sound, Bahamas.
Stromatolites form as intertidal and subtidal buildups shoreward of the algal ridge.
Results reported here pertain to the subtidal stromatolites, which grow in depths of less than 1 m at mean low tide and form ridges and columnar heads up to half a meter high.
mgg.rsmas.miami.edu /groups/geomic/STROMATOLITE/nature.HTML   (1147 words)

  
 Spirit Finds Stromatolites
Stromatolites typically are a form of blue-green algae that forms colonies- they grow layers of algae in a form something like cabbage, in thin sheets that are rounded and layered.
Many types of stromatolite lived in hypersaline lakes, and the extremely salty Martian soil is the remnant of such hypersaline brine.
Stromatolites grew in rounded layers, and each layer left a thin shell of limestone behind.
www.xenotechresearch.com /marsstro.htm   (638 words)

  
 Research: Cyanobacteria
We propose to test whether the resident microbial community is a key determinant in stromatolite morphology and our aim therefore is to systematically classify these potentially unique microbial communities, and particularly significant for Shark Bay, characterise their salt tolerance mechanisms.
Furthermore, stromatolite communities and other cyanobacterial populations may be a source of novel biomolecules.
As well as their roles in stromatolite morphogenesis, these organisms are infamous due to their massive proliferation in rivers and lakes and the associated toxicity of these "blue-green algae" blooms.
aca.mq.edu.au /Research/Research_Cyanobacteria.htm   (336 words)

  
 Nambung/Pinnacles (Western Australia) - Lake Thetis
Stromatolites can be defined as the fossilised remains of a colony or mat of "cyanobacteria".
Stromatolites found in Australia are as old as 3.5 billion years.
However, a necessity for stromatolite growth is the absence of any predator which is generally the case due to the high salinity of the water.
www.creativespirits.de /ozwest/pinnacles/lakethetis.html   (392 words)

  
 Microbolites
Stromatolites, for instance have a thinly laminated fabric, thrombolites have a mm to cm scale blotchy, unlayered fabric, and dendrites have a distinct bushy structure formed by calcified microbes (Riding 1991, 2000).
Stromatolitic crusts overgrowing corals and other organisms are present throughout the reef cores, and comprise a "major structural and volumetric constituent of the reef framework" (p.
Stromatolite columns may also be current-aligned (as in the image at the top of the page), and thus paleocurrent indicators.
www.geocities.com /earthhistory/newstrom.htm   (6576 words)

  
 Grand Hikes: Stromatolites in the Hakatai Shale
This mesa is bounded on the north by Phantom Creek Canyon, on the east by Bright Angel Canyon, on the south by the inner gorge of the Colorado River, and on the west by a canyon separating it from Cheops Pyramid, to which it is connected by a saddle on its northwest side.
Stromatolites survive to this day but they are nearly extinct, living a precarious existence in only a few localities worldwide, one at Shark Bay (Hamelin Pool Marine Nature Reserve) in Australia and another at several islands in the Bahamas.
Stromatolites are able to survive in Australia's Hamelin Pool because its water is twice as saline as normal sea water and many other forms of competitive and predatory marine life cannot survive there.
www.rockhounds.com /grand_hikes/hikes/stromatolites_in_the_hakatai   (8183 words)

  
 Kah - Stromastolites in earth History   (Site not responding. Last check: 2007-10-08)
Several of my recent and ongoing studies are aimed at deciphering the growth history of Precambrian stromatolite reefs to help understand environmental controls on stromatolite growth and lithification.
Stromatolite morphology has long been recognized as a potential environmental indicator - stromatolites with high synoptic relief commonly occur in deeper-water settings, and flat-laminated mats are typically restricted to shallow-water environments.
Although demonstration of these trends is still in it's infancy, my colleagues and I hope that we can test this relationship quantifying stromatolite lamina shape in individual bioherms that occur across different environments and using sequence stratigraphy as an independent means of inferring the magnitude and direction of environmental change.
web.eps.utk.edu /Faculty/kah/research2.htm   (724 words)

  
 Panspermia - Encyclopedia, History, Geography and Biography
It is in formations such as this that 3.5 billion year old fossilized algae microbes, the earliest known life on earth, were discovered.
Fossilized stromatolites or bacterial aggregates, the oldest of which are dated at 3.5 billion years old.
The bacteria that form stromatolites, cyanobacteria, are photosynthetic.
www.arikah.com /encyclopedia/Panspermia   (3355 words)

  
 Museum Grade Agatized Stromatolite
Stromatolite is fossilized algae colonies, identified as some of the oldest, and longest continually surviving forms of life on Earth.
There are stromatolites that have been dated to an astonishing 3.2 billion years ago (living while the Earth may have been still under frequent bombardment by asteroids), and there are still living colonies of the same algae today along certain shallow-water coasts.
This beautiful museum cabinet display piece is Wyoming stromatolite, aged about 400 million years, which shows the characteristic botryoidal structure (lumpy - like a bunch of grapes, or a "brain" -like structuring) of the outer surface of the ancient colony.
www.sciencemall-usa.com /brainstromo2.html   (196 words)

  
 Years Were Longer 1.3bln Years ago: Chinese Scientists   (Site not responding. Last check: 2007-10-08)
Stromatolite mainly consists of the fossil of blue algae, which,rich in chlorophyll, was the first procaryote to emerge on the earth.
The stromatolite samples used during the research this time were collected from a section of Yanshan mountain in Jixian county of Tianjin city in north China, where the most complete and informative stromatolite are widely acknowledged to be preserved.
An in-depth study of the microstructure of the stromatolite showed that the daily rhythm is represented by the basic layer, which is made up of a gray layer 0.01 mm to 0.05 mm thick and another transparent layer 0.3 mm to 0.8 mm thick.
www.freerepublic.com /focus/f-news/950911/posts   (1716 words)

  
 Life on Mars: Giant Fossils
Stromatolites, rock structures built by microbial organisms, are the most conspicuous evidence of early life on Earth and, hence, are the most appropriate target for investigation on Mars.
Stromatolites are the oldest known fossils, dating back more than 3 billion years.
Stromatolites are able to survive in the area because Hamelin Pool's water is twice as saline as normal sea water and seagrasses and many other forms of life cannot survive there.
www.resa.net /nasa/mars_life_gifossil.htm   (1134 words)

  
 stromatolite - Hutchinson encyclopedia article about stromatolite   (Site not responding. Last check: 2007-10-08)
Another mat grows on the trapped mud layer and this traps another layer of mud and so on.
The stromatolite grows to heights of a metre or so.
The oldest stromatolites have been dated at 3.46 billion years old.
encyclopedia.farlex.com /stromatolite   (145 words)

  
 Oxford Brookes - 8313 Sedimentology - Reefs through Time   (Site not responding. Last check: 2007-10-08)
Stromatolites show a variety of forms, related to environmental conditions, such as energy level and rate of sedimentation.
Desiccation features are common in stromatolites, particularly those formed in the intertidal or supratidal environment.
Laminations, as in stromatolites, tend to be highly irregular.
www.brookes.ac.uk /geology/8313/reeflect3.html   (953 words)

  
 Fossil Invertebrate Fossils For Sale
Stromatolites are found only in areas where other organisms that would normally keep down the bacterial numbers cannot survive, such as extremely salty bays.
Stromatolites are one of the World's oldest known marine Algae to be fossilized.
Even though stromatolites developed in an environment lacking in oxygen they produced and released vital oxygen which became an abundant gas in the atmosphere for the first time.
www.twoguysfossils.com /inverts_other.htm   (854 words)

  
 Draft 2:Stromatolite Paleoenvironment vs Present Bahamas Environment   (Site not responding. Last check: 2007-10-08)
This paper will look at stromatolites in paleoenvironments and their importance, and the environments for which they are present in the Bahamas.
I will be researching the paleoenvironments of stromatolites, examination of their abundance, and types of environments.
The role of microbes in accretion, lamination and early lithification of modern marine stromatolites.
jrscience.wcp.muohio.edu /fieldcourses01/MarineEcologyArticles/Draft2.StromatolitePaleoe.html   (244 words)

  
 Chesapeake Biological Laboratory - Title   (Site not responding. Last check: 2007-10-08)
Layered deposits of calcium carbonate known as stromatolites are the oldest macroscopic evidence of life on earth.
Modern stromatolites are still forming in the Bahamas, and CBL's Professor Roberta Marinelli has been investigating them with The Research Initiative on Bahamian Stromatolites (RIBS), a multi-investigator project funded under the National Science Foundation's Biocomplexity Program.
Stromatolites are complex interactions of microbes, sediments and the environment.
www.cbl.umces.edu /Research/ecologists/organism.htm   (1272 words)

  
 Untitled Document
Stromatolites formed everything from largely flat pond scum to well-cemented features that rose more than a meter above the surroundings.
The stromatolite is built by successive layers of trapped sediment, the “sticky” organisms allowing the sediment to stay on the steep side slopes.
B. This is a Devonian (the “age of fish”) stromatolite.
www.oberlin.edu /faculty/dhubbard/PersWebPage/Courses/CoralReefs/Reefs03/LabExedrciseKEY.html   (1134 words)

  
 Da Yoopers Guide to Michigan Stromatolites   (Site not responding. Last check: 2007-10-08)
Stromatolites were thought to have been extinct until forty years ago.
However, with the discovery of modern stromatolites in Shark Bay, Australia, and elsewhere, it is now known that some are actually comprised of living cyanobacteria that grow on top of each other at a rate of 1mm a year.
Stromatolite Outcrop in Lindberg's Quarry, Marquette County Michigan
www.dayooper.com /stromato.htm   (416 words)

  
 [No title]   (Site not responding. Last check: 2007-10-08)
Stromatolites form in hypersaline, normal marine, brackish and fresh, carbonate-rich water.
This precipitation can be active as in the case of some algae and cyanobacteria, or more passive as in the case of the stalks of diatoms which provide a substrate for calcite nucleation.
There are lots of diatoms on every stromatolite I have ever examined, which makes sense- they are epiphytic on the bigger filaments and epipelic and epilithic on the carbonate grains- it is hard to separate the habitats since some stroms accumulate carbonate layers daily and the diatoms no doubt do a lot of travelling.
www.indiana.edu /~diatom/traverti.dis   (368 words)

  
 Environmental Health Sciences
Marine Stromatolites are finely-laminated rock structures, consisting of fine layers of calcium carbonate precipitate.
This project is in collaboration with researchers from the Universities of Miami, Connecticut, Maryland, Duquesne, and St. Andrews (Scotland); and scientists at the NASA.
Stromatolites (not visable) occur in shallow subtidal waters.
www.sph.sc.edu /enhs/enhsadongoing.htm   (1098 words)

  
 Lower Proterozoic Stromatolite - Rare Massive Girvanella   (Site not responding. Last check: 2007-10-08)
Stromatolite is the oldest of all fossils, and with much labor (cutting and polishing), it is most beautiful.
The banding that commonly appears in stromatolite is a record of the growth patterns of colonies of microorganisms, principally photosynthetic prokaryotes (e.g, cyanobacteria).
This stromatolitic carbonate has been hand-polished to a mirror finish on one side exhibits a broad spectrum and intricate pattern of colors.
fossilmall.com /Stonerelic/stromatolite/DS519/DS519.htm   (352 words)

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