February 2018

New Clue for Fast Motion of the Hawaiian Hotspot

Earth History, Hawaii, Tectonic 10:00 PM

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<span style="font-family: "georgia" , "times new roman" , serif;">Geoscientists used to think volcanic hotspots were stationary. It helped us understand how tectonic plates - and continents - moved and where earthquakes lay. Now, evidence says they aren't stationary. Time to reassess?</span><br />
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The island chain of Hawaii consists of several volcanoes, which are fed by a "hotspot." In geosciences a "hotspot" refers to a phenomenon of columnar shaped streams, which transport hot material from the deep mantle to the surface.<br />
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Like a blow torch, the material burns through the Earth's crust and forms volcanoes. For a long time, it was assumed that these hotspots are stationary. If the tectonic plate moves across it, a chain of volcanoes evolves, with the youngest volcano at one end, the oldest at the other.<br />
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This concept was initially proposed for the Hawaiian Islands. They are the youngest end of the Hawaiian-Emperor chain that lies beneath the Northwest Pacific. But soon there was doubt over whether hotspots are truly stationary. The biggest contradiction was a striking bend of about 60 degrees in this volcanic chain, which originated 47 million years ago. <br />
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"If you try to explain this bend with just a sudden change in the movement of the Pacific Plate, you would expect a significantly different direction of motion at that time relative to adjacent tectonic plates," says Bernhard Steinberger of the GFZ German Research Center for Geosciences. <br />
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"But we have not found any evidence for that." Recent studies have suggested that apparently two processes were effective: On the one hand, the Pacific Plate has changed its direction of motion.<br />
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On the other hand, the Hawaiian hotspot moved relatively quickly southward in the period from 60 to about 50 million years ago -- and then stopped. If this hotspot motion is considered, only a smaller change of Pacific plate motions is needed to explain the volcano chain.<br />
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This hypothesis is now supported by work in which Steinberger is also involved. First author Kevin Konrad, Oregon State University in Corvallis, Oregon, and his team have evaluated new rock dating of volcanoes in the Rurutu volcanic chain, including, for example, the Tuvalu volcanic islands in the Western Pacific. <br />
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Furthermore, they added similar data from the Hawaiian-Emperor chain and the Louisville chain in the Southern Pacific. Based on the geography and the age of volcanoes in these three chains, researchers can look into the geological past and see how the three hotspots have moved relative to each other over millions of years.<br />
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The new data published in the journal Nature Communications shows that the relative motion of hotspots under the Rurutu and Louisville is small while the Hawaiian-Emperor hotspot displays strong motion between 60 and 48 million years ago relative to the other two hotspots.<br />
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"This makes it very likely that mainly the Hawaii hotspot has moved," says Steinberger. According to his geodynamic modelling the Hawaiian hotspot moved at a rate of several tens of kilometers per million years. Paleomagnetic data support this interpretation, says Steinberger. <br />
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"Our models for the motion of the Pacific Plate and the hotspots therein still have some inaccuracies. With more field data and information about the processes deep in the mantle, we hope to explain in more detail how the bend in the Hawaiian-Emperor chain has evolved."<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.gfz-potsdam.de/en/media-and-communication/news/details/article/another-clue-for-fast-motion-of-the-hawaiian-hotspot/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.gfz-potsdam.de/" rel="nofollow" target="_blank">GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre</a>.</span></i></u></div>

New Clue for Fast Motion of the Hawaiian Hotspot

Geoscientists used to think volcanic hotspots were stationary. It helped us understand how tectonic plates - and continents - moved ...

Scientists Found Evidence That Earth's Magnetic Poles May Be Getting Ready to Flip

earth, Earth's magnetic field, Tectonic 9:38 PM

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<tr><td class="tr-caption" style="text-align: center;">Earth’s geomagnetic field surrounds and protects our planet from harmful space radiation.</td></tr>
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<span style="font-family: Georgia, "Times New Roman", serif;">Using new data gathered from sites in southern Africa, University of Rochester researchers have extended their record of Earth's magnetic field back thousands of years to the first millennium.</span><br />
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The record provides historical context to help explain recent, ongoing changes in the magnetic field, most prominently in an area in the Southern Hemisphere known as the South Atlantic Anomaly.<br />
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"We've known for quite some time that the magnetic field has been changing, but we didn't really know if this was unusual for this region on a longer timescale, or whether it was normal," says Vincent Hare, who recently completed a postdoctoral associate appointment in the Department of Earth and Environmental Sciences (EES) at the University of Rochester, and is lead author of a paper published in Geophysical Research Letters.<br />
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<span style="font-family: "georgia" , "times new roman" , serif;">Weakening magnetic field a recurrent anomaly</span></h3>
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The new data also provides more evidence that a region in southern Africa may play a unique role in magnetic pole reversals.<br />
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The magnetic field that surrounds Earth not only dictates whether a compass needle points north or south, but also protects the planet from harmful radiation from space. Nearly 800,000 years ago, the poles were switched: north pointed south and vice versa.<br />
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The poles have never completely reversed since, but for the past 160 years, the strength of the magnetic field has been decreasing at an alarming rate. The region where it is weakest, and continuing to weaken, is a large area stretching from Chile to Zimbabwe called the South Atlantic Anomaly.<br />
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In order to put these relatively recent changes into historical perspective, Rochester researchers—led by John Tarduno, a professor and chair of EES—gathered data from sites in southern Africa, which is within the South Atlantic Anomaly, to compile a record of Earth's magnetic field strength over many centuries.<br />
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Data previously collected by Tarduno and Rory Cottrell, an EES research scientist, together with theoretical models developed by Eric Blackman, a professor of physics and astronomy at Rochester, suggest the core region beneath southern Africa may be the birthplace of recent and future pole reversals.<br />
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"We were looking for recurrent behavior of anomalies because we think that's what is happening today and causing the South Atlantic Anomaly," Tarduno says. "We found evidence that these anomalies have happened in the past, and this helps us contextualize the current changes in the magnetic field."<br />
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The researchers discovered that the magnetic field in the region fluctuated from 400-450 AD, from 700-750 AD, and again from 1225-1550 AD. This South Atlantic Anomaly, therefore, is the most recent display of a recurring phenomenon in Earth's core beneath Africa that then affects the entire globe.<br />
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"We're getting stronger evidence that there's something unusual about the core-mantel boundary under Africa that could be having an important impact on the global magnetic field," Tarduno says.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">A pole reversal? Not yet, say researchers</span></h3>
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The magnetic field is generated by swirling, liquid iron in Earth's outer core. It is here, roughly 1800 miles beneath the African continent, that a special feature exists. Seismological data has revealed a denser region deep beneath southern Africa called the African Large Low Shear Velocity Province. </div>
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The region is located right above the boundary between the hot liquid outer core and the stiffer, cooler mantle. Sitting on top of the liquid outer core, it may sink slightly, disturbing the flow of iron and ultimately affecting Earth's magnetic field.<br />
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A major change in the magnetic field would have wide-reaching ramifications; the magnetic field stimulates currents in anything with long wires, including the electrical grid. Changes in the magnetic field could therefore cause electrical grid failures, navigation system malfunctions, and satellite breakdowns.<br />
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A weakening of the magnetic field might also mean more harmful radiation reaches Earth—and trigger an increase in the incidence of skin cancer. Hare and Tarduno warn, however, that their data does not necessarily portend a complete pole reversal.<br />
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"We now know this unusual behavior has occurred at least a couple of times before the past 160 years, and is part of a bigger long-term pattern," Hare says. "However, it's simply too early to say for certain whether this behavior will lead to a full pole reversal."<br />
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Even if a complete pole reversal is not in the near future, however, the weakening of the magnetic field strength is intriguing to scientists, Tarduno says. "The possibility of a continued decay in the strength of the magnetic field is a societal concern that merits continued study and monitoring."<br />
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<span style="font-family: "georgia" , "times new roman" , serif;">In the Field: "Archaeomagnetism" at work</span></h3>
The researchers gathered data for this project from an unlikely source: ancient clay remnants from southern Africa dating back to the early and late Iron Ages. As part of a field called "archaeomagnetism," geophysicists team up with archaeologists to study the past magnetic field.<br />
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The Rochester team, which included several undergraduate students, collaborated with archaeologist Thomas Huffman of the University of Witwatersrand in South Africa, a leading expert on Iron Age southern Africa. The group excavated clay samples from a site in the Limpopo River Valley, which borders Zimbabwe, South Africa, and Botswana.<br />
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During the Iron Age in southern Africa, around the time of the first millennium, there was a group of Bantu-speaking people who cultivated grain and lived in villages composed of grain bins, huts, and cattle enclosures. <br />
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Draughts were devastating to their agriculturally based culture. During periods of draught, they would perform elaborate ritual cleansings of the villages by burning down the huts and grain bins.<br />
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"When you burn clay at very high temperatures, you actually stabilize the magnetic minerals, and when they cool from these very high temperatures, they lock in a record of the earth's magnetic field," Tarduno says.<br />
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Researchers excavate the samples, orient them in the field, and bring them back to the lab to conduct measurements using magnetometers. In this way, they are able to use the samples to compile a record of Earth's magnetic field in the past.<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://dx.doi.org/10.1002/2017GL076007" rel="nofollow" target="_blank">materials </a>provided by<span style="background-color: white; color: black; display: inline; float: none; font-size: 14.336px; font-weight: 400; letter-spacing: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"> </span><a href="https://www.rochester.edu/" rel="nofollow" target="_blank">University of Rochester.</a></span></i></u></div>
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Scientists Found Evidence That Earth's Magnetic Poles May Be Getting Ready to Flip

Earth’s geomagnetic field surrounds and protects our planet from harmful space radiation. Using new data gathered from sites in south...

Facts About Pangaea the Most Recent Supercontinent

Earth History, Tectonic 9:01 PM

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<b>Pangaea </b>was a supercontinent that existed during the late Paleozoic and early Mesozoic eras.<br />
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It assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 million years ago. In contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the<b> southern hemisphere</b> and surrounded by a superocean, <b>Panthalassa</b>. <br />
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Pangaea formed through a gradual process spanning a few hundred million years. Beginning about 480 million years ago, a continent called <b>Laurentia</b>, which includes parts of North America, merged with several other micro-continents to form Euramerica. <b>Euramerica</b> eventually collided with Gondwana, another supercontinent that included Africa, Australia, South America and the Indian subcontinent.<br />
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Pangaea was<b> the most recent</b> supercontinent to have existed and the first to be reconstructed by geologists.<br />
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The name "Pangaea/Pangea" is derived from Ancient Greek pan (πᾶν, "all, entire, whole") and <b>Gaia </b>(Γαῖα, "Mother Earth, land")<br />
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<tr><td class="tr-caption" style="text-align: center;">The distribution of fossils across the continents is one line of evidence pointing to the existence of Pangaea.</td></tr>
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Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart. For example, fossils of the <b>therapsid</b> <b>Lystrosaurus </b>have been found in South Africa, India and Antarctica, alongside members of the Glossopteris flora, whose distribution would have ranged from the polar circle to the equator if the continents had been in their present position; similarly, the freshwater reptile Mesosaurus has been found in only localized regions of the coasts of Brazil and West Africa.<br />
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<b>Paleomagnetic </b>study of apparent polar wandering paths also support the theory of a supercontinent. Geologists can determine the movement of continental plates by examining the orientation of magnetic minerals in rocks; when rocks are formed, they take on the magnetic properties of the Earth and indicate in which direction the poles lie relative to the rock.<br />
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The continuity of <b>mountain chains</b> provides further evidence for Pangaea. One example of this is the Appalachian Mountains chain, which extends from the southeastern United States to the Caledonides of Ireland, Britain, Greenland, and Scandinavia.<br />
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There were<b> three major phases</b> in the break-up of Pangaea. The <b>first phase</b> began in the Early-Middle Jurassic (about 175 Ma), when Pangaea began to rift from the Tethys Ocean in the east to the Pacific in the west.<br />
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The <b>second major phase</b> in the break-up of Pangaea began in the Early Cretaceous (150–140 Ma), when the minor supercontinent of Gondwana separated into multiple continents (Africa, South America, India, Antarctica, and Australia).<br />
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The <b>third major and final phase</b> of the break-up of Pangaea occurred in the early Cenozoic (Paleocene to Oligocene). Laurasia split when North America/Greenland (also called Laurentia) broke free from Eurasia, opening the Norwegian Sea about 60–55 Ma.<br />
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What can also be observed in relation to tectonic plates and Pangaea, is the formations to such plates. <b>Mountains and valleys</b> form due to tectonic collisions as well as earthquakes and chasms. Consequentially, this shaped Pangaea and animal adaptations.<br />
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When Pangaea separated, the reorganization of the continents changed the function of the oceans and seaways. The restructuring of the continents, changed and altered the distribution of warmth and <b>coolness </b>of the oceans. When North America and South America connected, it stopped equatorial currents from passing from the Atlantic Ocean to the Pacific Ocean.<br />
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The creation of the <b>new ocean</b> that caused a circumpolar current eventually led to atmospheric currents that rotated from west to east. Atmospheric and oceanic currents stopped the transfer of warm, tropical air and water to the higher latitudes.<br />
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There is evidence to suggest that the deterioration of northern Pangaea contributed to the <b>Permian Extinction</b>, one of Earth’s five major mass extinction events, which resulted in the loss of over 90% of marine and 70% of terrestrial species.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">See also: </span></b><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2017/05/what-pangea-would-look-like-with-our.html" target="_blank">What Pangea Would Look Like With Our Current International Border</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2018/01/the-largest-insect-ever-existed-was.html" target="_blank">The Largest Insect Ever Existed Was a Giant "Dragonfly"</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2016/12/10-interesting-facts-about-geological.html" target="_blank">10 Interesting Facts About the Geological Time Scale</a></span></div>

Facts About Pangaea the Most Recent Supercontinent

Pangaea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental un...

Extinct Lakes of the American Desert West

climate, USA 6:00 PM

Extinct Lakes of the American Desert West

Superior dry lake bed near Black Canyon California Identification of ancient lake shoreline features began with early explorers of the...

Conch Pearl: The Only Natural Pink Pearl

gemstones 5:13 PM

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<tr><td class="tr-caption" style="text-align: center;">Collection of fine quality pink conch pearls. photo: MONILI </td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">What are conch pearls?</span></h3>
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Pretty and pastel-hued, a conch pearl is a calcareous concretion produced by the Queen conch (pronounced “conk”) mollusc, which is a large, edible sea snail. Most often pink in colour and normally oval shaped, the finest examples display a wave-like “flame” structure on their surface and have a creamy, porcelain-like appearance and unique shimmer.<br />
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Unlike pearls harvested from oysters, conch pearls – like other naturally occurring pearls, including the Melo and Giant Clam – are non-nacreous, which means they are not made of nacre, the substance that gives traditional pearls their iridescent lustre.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">How are conch pearls formed?</span></h3>
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It is believed that a conch pearl is formed when an irritant, often a broken bit of shell, enters the Queen conch, around which a calcareous concentration forms. These concentric layers of fibrous crystals build up around the irritant, in the same way as kidney stones grow in humans.<br />
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Unlike oysters, which can be prized open to reveal the exact location of a pearl, no-one knows precisely where conch pearls are formed because of the elaborate whorled structure of a conch shell. Grown inside a pearl sac in the orange mantle of the Queen conch, they are normally found at the same time as the meat is cut out of the shell.<br />
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<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-Aut00hnzVx8/WmYBsS3W-eI/AAAAAAAAOqA/SBWzb6Fyw24ulmNO8luejHEhQT_QqVIQgCLcBGAs/s1600/Queen%2Bconches%2Bare%2Bharvested%2Bby%2Bteams%2Bof%2Bfishermen%2Bin%2Bthe%2Bwarm%2Btropical%2Bwaters%2Bof%2Bthe%2BCaribbean%252C%2Bfrom%2Bthe%2BYucat%25C3%25A1n%2Ball%2Bthe%2Bway%2Bup%2Bto%2BBermuda%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Conch Pearl: The Only Natural Pink Pearl " border="0" data-original-height="760" data-original-width="760" height="640" src="https://2.bp.blogspot.com/-Aut00hnzVx8/WmYBsS3W-eI/AAAAAAAAOqA/SBWzb6Fyw24ulmNO8luejHEhQT_QqVIQgCLcBGAs/s640/Queen%2Bconches%2Bare%2Bharvested%2Bby%2Bteams%2Bof%2Bfishermen%2Bin%2Bthe%2Bwarm%2Btropical%2Bwaters%2Bof%2Bthe%2BCaribbean%252C%2Bfrom%2Bthe%2BYucat%25C3%25A1n%2Ball%2Bthe%2Bway%2Bup%2Bto%2BBermuda%2B%25281%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Queen conches are harvested by teams of fishermen in the warm tropical waters of the Caribbean, from the Yucatán all the way up to Bermuda (Image featured in The Pink Pearl, courtesy of Susan Hendrickson).</td></tr>
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</div>
<h3 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Where are conch pearls found?</span></h3>
<div style="text-align: left;">
Found in large groups of up to 200, Queen conches live among beds of sea grass in the warm tropical waters of the Caribbean, from the Yucatán all the way up to Bermuda.<br />
<br />
Conch pearls are a beautiful by-product of the fishing industry in this region. Caught primarily for its meat, the Queen conch is eaten throughout the Caribbean and the US, raw in salads or cooked in local delicacies such as chowders and fritters.<br />
<br />
Overfishing in many of the locations in which the Queen conch is found has forced all but three conch-producing countries to ban fishing to protect populations, which it is predicted will not recover for decades. This means fewer conch pearls are coming to market.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-3zgTOFcjWf0/Wn8R5wfS_tI/AAAAAAAAO0c/1Kb-XbHuJSIExvOF9-Hu_NLbyMD-cUtDQCLcBGAs/s1600/Conch%2BPearl%2BThe%2BOnly%2BNatural%2BPink%2BPearl.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Conch Pearl: The Only Natural Pink Pearl " border="0" data-original-height="759" data-original-width="760" height="638" src="https://4.bp.blogspot.com/-3zgTOFcjWf0/Wn8R5wfS_tI/AAAAAAAAO0c/1Kb-XbHuJSIExvOF9-Hu_NLbyMD-cUtDQCLcBGAs/s640/Conch%2BPearl%2BThe%2BOnly%2BNatural%2BPink%2BPearl.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pink conch pearls pictured alongside Melo and Giant Clam pearls, all of which are created naturally, making them exceptionally rare. (Image featured in The Pink Pearl, courtesy of Susan Hendrickson).</td></tr>
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At one time, Queen conches were also found off the coast of Florida, where it is now illegal to fish them. </div>
<h3 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Why are conch pearls so rare?</span></h3>
<div style="text-align: left;">
In a world dominated by cultured pearls, natural pearls, formed without human intervention, come with the “rare” tag that makes them infinitely more desirable. Just like gemstones, which are more valuable if they are sold in their natural, untreated state, the exclusivity of conch pearls is partly down to the fact that they are 100% as nature intended. However, there are other factors that contribute to their rarity.  </div>
<h3 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Size, Shape & Care</span></h3>
<div style="text-align: left;">
Most conch pearls have an elongated, oval, or baroque shape, and near-round specimens are very rare. Conch pearls weigh significantly more than oyster pearls, with a specific gravity of 2.85; and unlike other pearls, are sized by carat weight. Conch pearls are rated harder than nacreous pearls resulting in more resistance to erosion and corrosion than nacreous pearls.<br />
<br />
Although conch pearls can be found over 100 carats, larger sizes (above 5 carats) of conch pearls are uncommon, with the average size being less than 3 carats. Due to the high value of conch pearls, drilling and/or gluing should be avoided in the mounting, as this will devalue the pearl. Known as the night gem, prolonged exposure to sunlight (ultraviolet light) can have a dulling and fading effect.<br />
<br />
Indoor lighting does not seem to have effects on the pearls. It is an organic gem, therefore, jewelry should be used with care-no gardening, rock climbing, safaris and washing dishes is also out of the question!<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-NxNYQQik5Hc/Wn8WXc5wqxI/AAAAAAAAO0o/my-z8BGobP4N3x14mABL0MNXOct2tyshACLcBGAs/s1600/Conch%2BPearl%2BThe%2BOnly%2BNatural%2BPink%2BPearl%2B1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Conch Pearl: The Only Natural Pink Pearl " border="0" data-original-height="540" data-original-width="795" height="434" src="https://4.bp.blogspot.com/-NxNYQQik5Hc/Wn8WXc5wqxI/AAAAAAAAO0o/my-z8BGobP4N3x14mABL0MNXOct2tyshACLcBGAs/s640/Conch%2BPearl%2BThe%2BOnly%2BNatural%2BPink%2BPearl%2B1.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pink conch pearls</td></tr>
</tbody></table>
<h3 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Conch pearl value</span></h3>
A combination of size, shape, colour and flame effect determines the value of a conch pearl. “Prices vary wildly and have increased rapidly for the rarest pearls,” says Sue Hendrickson. “Therefore, people are reluctant to quote them. Excellent pearls today can cost as much as $15,000 per carat and more, but those are the exceptionally rare ones. Top-grade conch pearls are more typically around $4,000-$7,000 per carat and nice, but not necessarily perfect, pearls around $2,000-$3,000.”<br />
<br />
<br />
<b><span style="font-family: "georgia" , "times new roman" , serif;">See also: </span></b><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2018/07/different-types-and-colours-of-moonstone.html" target="_blank">Different Types and Colours of Moonstone</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2018/08/what-are-organic-gemstones.html" target="_blank">What Are Organic Gemstones?</a></span></div>
</div>

Conch Pearl: The Only Natural Pink Pearl

Collection of fine quality pink conch pearls. photo: MONILI What are conch pearls? Pretty and pastel-hued, a conch pearl is a ca...

Gallium Is A Metal That Melts In Your Hands

Geochemistry, Researches 7:21 PM

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<br />
<br />
<b>Gallium </b>is a soft, silvery metal used primarily in electronic circuits, semiconductors and light-emitting diodes (LEDs). It is also useful in high-temperature thermometers, barometers, pharmaceuticals and nuclear medicine tests. The element has no known biological value.<br />
<br />
In nature, gallium is never found as a <b>free element</b> and cannot be found in a substantial amount in any minerals. Rather, it exists in trace amounts in various compounds, including zinc ores and bauxite.<br />
<br />
Very pure gallium metal has a silvery color and its solid metal fractures conchoidally like glass. Gallium liquid <b>expands </b>by 3.1% when it solidifies; therefore, it should not be stored in glass or metal containers because the container may rupture when the gallium changes state.<br />
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Gallium shares the <b>higher-density liquid</b> state with a short list of other materials that includes water, silicon, germanium, antimony, bismuth, and plutonium.<br />
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The <b>melting point</b> of gallium, at 302.9146 K (29.7646 °C, 85.5763 °F), is just above room temperature, and is approximately the same as the average summer daytime temperatures in Earth's mid-latitudes. <br />
<br />
The melting point of gallium allows it to melt in the human hand, and then refreeze if removed. The liquid metal has a strong tendency to <b>supercool </b>below its melting point/freezing point.<br />
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Gallium is one of the four <b>non-radioactive</b> metals (with caesium, rubidium, and mercury) that are known to be liquid at, or near, normal room temperature. <br />
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Of the four, gallium is the only one that is neither highly <b>reactive </b>(rubidium and caesium) nor highly <b>toxic </b>(mercury) and can therefore be used in metal-in-glass high-temperature thermometers.<br />
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<a href="https://2.bp.blogspot.com/-uieX1VkVWGY/WpQzS6MfRkI/AAAAAAAAPBM/pQlGJhyZC-YX7Qa3_YjyjwOjf0hVAF5oACLcBGAs/s1600/Gallium%2Bmetal%2Bmelting%2Ba%2Bsoda%2Bcan%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Gallium Is A Metal That Melts In Your Hands" border="0" data-original-height="720" data-original-width="1280" height="360" src="https://2.bp.blogspot.com/-uieX1VkVWGY/WpQzS6MfRkI/AAAAAAAAPBM/pQlGJhyZC-YX7Qa3_YjyjwOjf0hVAF5oACLcBGAs/s640/Gallium%2Bmetal%2Bmelting%2Ba%2Bsoda%2Bcan%2B%25281%2529.jpg" title="" width="640" /></a></div>
<b><span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.youtube.com/watch?v=FaMWxLCGY0U" rel="nofollow" target="_blank">See video </a></span></b><br />
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Gallium does <b>not crystallize</b> in any of the simple crystal structures. The stable phase under normal conditions is orthorhombic with 8 atoms in the conventional unit cell. Within a unit cell, each atom has only one nearest neighbor (at a distance of 244 pm).<br />
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Gallium does not exist as a free element in the Earth's crust, and the few high-content minerals, such as <b>gallite </b>(CuGaS<sub>2</sub>), are too rare to serve as a primary source. <br />
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Points To Keep in Mind</span></h4>
<ul style="text-align: left;">
<li>Gallium may temporarily discolor your skin. This is because it wets skin. </li>
<li>Gallium is not toxic. It is used in pharmaceuticals, so you could probably swallow it and be okay, but it's not recommended, plus it would be an expensive snack.</li>
<li>Gallium attacks other metals, so do not let it come into contact with jewelry or store it in metal containers.</li>
<li>Gallium expands as it cools, so it usually kept in a plastic bag or flexible container.</li>
</ul>
<div style="text-align: left;">
</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">How To Melt Gallium</span></h4>
<div style="text-align: left;">
What could be easier? Simply place the piece of gallium in the palm of your hand and let the warmth of your body heat do the work!<br />
<h3>
<span style="color: white;"><span style="background-color: white;"><span style="font-size: xx-small;"><span style="font-family: "times" , "times new roman" , serif;">How To Melt Gallium</span></span></span></span></h3>
</div>
<div style="text-align: left;">
<b><span style="font-family: "georgia" , "times new roman" , serif;">See also:</span></b><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2017/12/how-does-trapiche-emerald-form.html" target="_blank">How Does a Trapiche Emerald Form?</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2017/06/pleochroism-in-tanzanite.html" target="_blank">Pleochroism in Tanzanite</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2016/12/how-do-asterism-minerals-form.html" target="_blank">How Do Asterism Minerals Form?</a></span></div>
</div>

Gallium Is A Metal That Melts In Your Hands

Gallium is a soft, silvery metal used primarily in electronic circuits, semiconductors and light-emitting diodes (LEDs). It is also use...

How Magma Feeds Volcanic Eruptions

Magma, volcano 5:41 PM

How Magma Feeds Volcanic Eruptions

Mount Agung A novel research study by scientists at the University of Liverpool has provided new insights into how molten rock (magma...

Download the International Chronostratigraphic Chart 2018

Chronostratigraphic 6:55 PM

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<br />
The International Commission on Stratigraphy (ICS), sometimes referred to by the unofficial name "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global scale.<br />
<h3 style="text-align: left;">
   <span style="font-family: Georgia, "Times New Roman", serif;">Chart</span>  </h3>
<div style="text-align: left;">
<span style="font-family: Arial; font-size: x-small;">C</span>lick here (<a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02.pdf">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02.jpg">JPG</a>) to download the latest version (v2018/02) of the International Chronostratigraphic Chart. </div>
<h4 style="text-align: left;">
<span style="font-family: Georgia, "Times New Roman", serif;">Translations of the chart: </span></h4>
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Chinese  (v2017/02: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02Chinese.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02Chinese.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Finnish  (v2017/02: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02Finnish.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02Finnish.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Netherlands Dutch (v2017/02: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02NLDutch.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02NLDutch.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Belgium Dutch (v2017/02: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02BEDutch.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2017-02BEDutch.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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American Spanish (v2016/04: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2016-04SpanishAmerDraft.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2016-04SpanishAmerDraft.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Spanish (v2015/01: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Spanish.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Spanish.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Basque (v2015/01: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Basque.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Basque.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Catalan (v2015/01: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Catalan.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Catalan.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Norwegian (v2015/01: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Norwegian.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Norwegian.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Lithuanian (v2015/01: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Lithuanian.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01Lithuanian.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Japanese (v2014/02: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2014-02Japanese.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2014-02Japanese.jpg" rel="nofollow" target="_blank">JPG</a>), </div>
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Portuguese (v2013/01: <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2013-01Portuguese_PT.pdf" rel="nofollow" target="_blank">PDF</a> or <a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2013-01Portuguese_PT.jpg" rel="nofollow" target="_blank">JPG</a>)</div>
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French (<a href="http://www.stratigraphy.org/ICSchart/ChronostratChart2012French.pdf" rel="nofollow" target="_blank">v2012</a>).</div>
</div>

Download the International Chronostratigraphic Chart 2018

The International Commission on Stratigraphy (ICS), sometimes referred to by the unofficial name "International Stratigraphic Com...

Continental Interiors May Not Be as Tectonically Stable as Geologists Think

earth, Tectonic 8:46 PM

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<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-xyMfzO1s7aE/WoxeNmzIGDI/AAAAAAAAO7Q/yW1usdCTXMEerS3xayuPRkDi1XRlIZxXgCLcBGAs/s1600/Continental%2BInteriors%2BMay%2BNot%2BBe%2Bas%2BTectonically%2BStable%2Bas%2BGeologists%2BThink.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Continental Interiors May Not Be as Tectonically Stable as Geologists Think" border="0" data-original-height="955" data-original-width="1232" height="496" src="https://4.bp.blogspot.com/-xyMfzO1s7aE/WoxeNmzIGDI/AAAAAAAAO7Q/yW1usdCTXMEerS3xayuPRkDi1XRlIZxXgCLcBGAs/s640/Continental%2BInteriors%2BMay%2BNot%2BBe%2Bas%2BTectonically%2BStable%2Bas%2BGeologists%2BThink.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cratonic lithosphere with a high-density root undergoes delamination when perturbed by mantle plumes from beneath. The removed cratonic root then thermally grows back, with its rock fabrics preserving recent mantle deformation. Credit: Lijun Liu</td></tr>
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A University of Illinois-led team has identified unexpected geophysical signals underneath tectonically stable interiors of South America and Africa. The data suggest that geologic activity within stable portions of Earth's uppermost layer may have occurred more recently than previously believed. The findings, published in Nature Geoscience, challenge some of today's leading theories regarding plate tectonics.<br />
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The most ancient rocks on Earth are located within continental interiors, far from active tectonic boundaries where rocks recycle back into the planet's interior. These strong, buoyant and deeply rooted blocks of Earth, called cratons, have been drifting on the surface for billions of years, seemingly undisturbed. They occasionally join and break apart along their edges in a dance called the supercontinent cycle.<br />
<br />
"We usually think of cratons as being cold, stable and low-elevation," said professor of geology and study co-author Lijun Liu. "Cold because the rocks are far above the hot mantle layers, stable because their crusts have not been disturbed significantly by faulting or deformation, and their low elevation is because they have been sitting there, eroding down for billions of years." <br />
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<h3 style="text-align: left;">
<span style="font-size: small;"><span style="font-family: "georgia" , "times new roman" , serif;">However, there are places where cratons don't follow these rules.</span></span></h3>
"For example, there are regions of high topography within the cratons of South America and Africa," said graduate student and lead author Jiashun Hu. The researchers processed geophysical data with the Blue Waters supercomputer at the National Center for Supercomputing Applications at Illinois hoping to better understand these high-elevation regions.<br />
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The thick roots of cratons have been thought to be buoyant due to their low-density mineral content, allowing them to float on top of the hot underlying mantle. However, the new data indicate that the cold mantle that lies below these regions in South America and Africa - once joined as part of the supercontinent Pangea - has a layered structure and that the lower layer was more dense in the past than it is today, Liu said.<br />
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This density difference could be the result of a process called mantle delamination. During delamination, the denser lower mantle layer peels away from the buoyant upper layer under the crust of the craton after interacting with hot magma from mantle plumes, the researchers said.<br />
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"From several types of seismic imaging data, we can see what we think are delaminated mantle slabs sinking into the hot, viscous deep mantle," Liu said.<br />
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"The material that subsequently grows back at the roots of the cratons after delamination, due to cooling from above, is probably compositionally much less dense than what was there before," said geology professor Craig Lundstrom. "That adds buoyancy, and that force from buoyancy could be what forms the anomalously high topography."<br />
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This multidisciplinary study is beginning to give the team a very logical - albeit complicated - update on the story of Earth's tectonic history, the researchers said.<br />
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"The high topography of Africa and South America is only part of the story," Hu said. "There are many geologic phenomena such as the location of hotspot trajectories, continental volcanism, surface uplift and erosion, as well as seismically imaged deformation within the craton roots that all seem to correlate well with the proposed delamination event, implying a potential causal relationship."<br />
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There is also evidence to support other locations of craton-plume interaction during other times in Earth's history.<br />
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"The rock record shows that uplift and erosion events have taken place during previous supercontinent cycles," said geology professor and School of Earth, Society and Environment director Stephen Marshak.<br />
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"A related study discusses what might be a similar event, namely continental uplift possibly related to delamination of cratonic lithosphere that caused the period of global erosion resulting in the Great Unconformity, which is the contact between Precambrian basement rock and Paleozoic sedimentary strata."<br />
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For now, it is not clear if and how craton-plume interaction may affect modern-day earthquake activity and volcanism in areas thought of as geologically inactive. However, the study marks new thinking in how geologists may understand the so-called stable cratons.<br />
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<br />
<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://news.illinois.edu/view/6367/614015" rel="nofollow" target="_blank">materials </a>provided by <a href="http://www.illinois.edu/" rel="nofollow" target="_blank">University of Illinois</a>.</span></u></i></div>

Continental Interiors May Not Be as Tectonically Stable as Geologists Think

Cratonic lithosphere with a high-density root undergoes delamination when perturbed by mantle plumes from beneath. The removed cratonic r...

Land Plants Appeared on Land 100 Million Years Earlier Than Scientists Thought

Earth History, evolution 7:32 PM

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<span style="font-family: "georgia" , "times new roman" , serif;">For the first four billion years of Earth's history, our planet's continents would have been devoid of all life except microbes.</span><br />
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All of this changed with the origin of land plants from their pond scum relatives, greening the continents and creating habitats that animals would later invade.<br />
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The timing of this episode has previously relied on the oldest fossil plants which are about 420 million years old.<br />
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New research, published today in the journal Proceedings of the National Academy of Sciences, indicates that these events actually occurred a hundred million years earlier, changing perceptions of the evolution of the Earth's biosphere.<br />
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Plants are major contributors to the chemical weathering of continental rocks, a key process in the carbon cycle that regulates Earth's atmosphere and climate over millions of years.<br />
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The team used 'molecular clock' methodology, which combined evidence on the genetic differences between living species and fossil constraints on the age of their shared ancestors, to establish an evolutionary timescale that sees through the gaps in the fossil record.<br />
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Dr Jennifer Morris, from the University of Bristol's School of Earth Sciences and co-lead author on the study, explained: "The global spread of plants and their adaptations to life on land, led to an increase in continental weathering rates that ultimately resulted in a dramatic decrease the levels of the 'greenhouse gas' carbon dioxide in the atmosphere and global cooling.<br />
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"Previous attempts to model these changes in the atmosphere have accepted the plant fossil record at face value -- our research shows that these fossil ages underestimate the origins of land plants, and so these models need to be revised."<br />
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Co-lead author Mark Puttick described the team's approach to produce the timescale. He said: "The fossil record is too sparse and incomplete to be a reliable guide to date the origin of land plants. Instead of relying on the fossil record alone, we used a 'molecular clock' approach to compare differences in the make-up of genes of living species -- these relative genetic differences were then converted into ages by using the fossil ages as a loose framework.<br />
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"Our results show the ancestor of land plants was alive in the middle Cambrian Period, which was similar to the age for the first known terrestrial animals."<br />
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One difficulty in the study is that the relationships between the earliest land plants are not known. Therefore the team, which also includes members from Cardiff University and the Natural History Museum, London, explored if different relationships changed the estimated origin time for land plants.<br />
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Leaders of the overall study, Professor Philip Donoghue and Harald Schneider added: "We used different assumptions on the relationships between land plants and found this did not impact the age of the earliest land plants.<br />
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"Any future attempts to model atmospheric changes in deep-time must incorporate the full range of uncertainties we have used here."<br />
<a href="http://www.geologyin.com/2017/10/fossils-of-ancient-trees-show-they.html" target="_blank"> see also: Fossils of Ancient Trees Show They Bizarrely Ripped Themselves Apart</a><br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://www.bristol.ac.uk/news/2018/february/plant-evolution.html" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.bristol.ac.uk/" rel="nofollow" target="_blank">University of Bristol</a>.</span></i></u></div>

Land Plants Appeared on Land 100 Million Years Earlier Than Scientists Thought

For the first four billion years of Earth's history, our planet's continents would have been devoid of all life except microbes...

Swarm of 200 Earthquakes Hits Yellowstone Supervolcano

Earthquakes, USA, Yellowstone 4:43 PM

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Regular earthquakes are bad enough. Volcanoes too. But an earthquake swarm at a supervolcano? That really sounds like it could be scary, and scientists say they've just detected such a phenomenon at the site of Yellowstone caldera.<br />
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According to geophysicists with the United States Geological Survey (USGS), the past fortnight has seen Yellowstone supervolcano shaken by a swarm of over 200 earthquakes since February 8, accompanied by innumerable smaller tremors too faint to accurately record.<br />
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Small earthquake swarm at <a href="https://twitter.com/YellowstoneNPS?ref_src=twsrc%5Etfw">@YellowstoneNPS</a>, Feb 8-present, 180 events located thus far by <a href="https://twitter.com/UUSS_Quake_Info?ref_src=twsrc%5Etfw">@UUSS_Quake_Info</a>. Location similar to last summer’s swarm. This is a common area of swarm seismicity. No other changes noted in Yellowstone activity. <a href="https://t.co/n1ZfCjtdrx">pic.twitter.com/n1ZfCjtdrx</a></div>
— USGS Volcanoes🌋 (@USGSVolcanoes) <a href="https://twitter.com/USGSVolcanoes/status/965318586322518017?ref_src=twsrc%5Etfw">February 18, 2018</a></blockquote>
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Despite how alarming this cavalcade of seismic activity might seem – considering its unnerving proximity to one of nature's most potentially devastating powder kegs – scientists say we shouldn't be panicked.<br />
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Researchers Mike Poland and Jamie Farrell from Yellowstone Volcano Observatory explain in a USGS update that swarms like this account for more than half of the seismic activity at Yellowstone, and they've never actually been known to contribute to volcanic activity at the caldera.<br />
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"This is what Yellowstone does; this is Yellowstone being Yellowstone," Poland told Live Science.<br />
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"It experiences swarms all the time."<br />
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Case in point: last June, the region experienced an epic earthquake swarm that was 10 times more turbulent, breaking Yellowstone records on its way to ultimately producing some 2,400 quakes by September.<br />
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Ordinarily, the caldera sees around 1,500–2,000 earthquakes per year, with about half taking place during swarms. In the current swarm, the largest earthquake reached a magnitude of 2.9 on the Richter scale, whereas last year's quakes topped out at a magnitude of 4.4.<br />
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These events might not produce fiery eruptions from Yellowstone's expansive magma chambers, but they're still a valuable opportunity for scientists to study the behaviour of the caldera system.<br />
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The latest outbreak took place in an area around 13 kilometres (8 miles) north-east of West Yellowstone, Montana, close to last year's 2,400-strong swarm. The researchers say it's possible the new flare-up is actually a continuation of the 2017 incident.<br />
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That might seem like a long stretch, but on the vast timescale over which seismic activity plays out, it's actually just a blip – and the researchers even say both the 2017 and 2018 swarms may actually hark back to a quake from the previous century.<br />
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"One of the potential explanations for why this area is so swarmy is that the whole crust in the area is still adjusting to the big earthquake in 1959," Poland told Live Science.<br />
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That episode, which induced the surrounding landscape to plummet by several metres and provoked seiches (standing waves) on Hebgen Lake for 12 hours, was the largest historic earthquake in the region, killing dozens of people in a landslide.<br />
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The 7.3-7.5 magnitude earthquake was due to stresses along faults under the region, but Yellowstone is also susceptible to pressure changes beneath the surface due to the buildup and withdrawal of fluids like magma and hydrothermal water, plus gases too.<br />
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For now, there's no indication that these suspected after-effects are actually a sign of any impending greater seismic activity to come – nor a prelude to an eruption, but if (or when) a volcanic outburst is next unleashed at Yellowstone, it likely won't be the cataclysm many fear, the researchers say.<br />
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"If Yellowstone erupts, it's most likely to be a lava flow, as occurred in nearly all the 80 eruptions since the last 'supereruption' 640,000 years ago," Farrell told Newsweek last June.<br />
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"A lava flow would be a big deal at Yellowstone, but would have very little regional or continental effect."<br />
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Of course, that's just likelihood being talked about there. One year or another – although it could be countless millennia away – the supervolcano will inevitably undergo another of its incredibly rare, but unimaginably catastrophic super-eruptions.<br />
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To give you an idea of how bad that (hopefully very far-off) explosion could be, NASA estimates the global consequences could be graver than a planet-devastating asteroid strike, with ash clouds likely to starve Earth of sunlight in a choking, years-long volcanic winter.<br />
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The good news is, that's probably not what this earthquake swarm is all about.<br />
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Right now, we can be thankful that Yellowstone is being sleepy – especially since, even while it's napping, it remains a bizarre and unpredictable place, at turns deadly, surprising, and confounding.<br />
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As long as it's not super-erupting, we'll take what we can get – and in any case, the latest swarm looks like it could be over for now.<br />
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"It's slowly petering out, although these things wax and wane, so it's a bit difficult to say that it's ending," Poland told Newsweek.<br />
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"Yellowstone is just a very swarmy place."<br />
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<b><span style="font-family: Georgia, "Times New Roman", serif;"><a href="http://www.geologyin.com/2014/11/study-yellowstone-magma-much-bigger.html" target="_blank">Study: Yellowstone Magma Much Bigger Than Thought </a></span></b></div>