More Than 99 Carats of Arkansas Diamonds Found at Park in 2019

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-6tFjWmgqkso/Xklb3D5kLRI/AAAAAAAAR7o/toIFyrkowio9OU-DKAiWq2Ej8mEZqEaqACLcBGAsYHQ/s1600/Woman%2BFinds%2B3.29%2BCarat%2BDiamond%2Bat%2BArkansas%2BState%2BPark.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="More Than 99 Carats of Arkansas Diamonds Found at Park in 2019" border="0" data-original-height="771" data-original-width="1600" height="308" src="https://1.bp.blogspot.com/-6tFjWmgqkso/Xklb3D5kLRI/AAAAAAAAR7o/toIFyrkowio9OU-DKAiWq2Ej8mEZqEaqACLcBGAsYHQ/s640/Woman%2BFinds%2B3.29%2BCarat%2BDiamond%2Bat%2BArkansas%2BState%2BPark.jpg" title="" width="640" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">Pat Choate, of Jacksonville, found a 3.29-carat brown diamond she named "Illusive Dream," calling it a dream come true after many years of hard work searching for diamonds </td></tr> </tbody></table> <br /> Visitors from Arkansas, 36 other states, and one foreign country found 491 diamonds during the year at Crater of Diamonds State Park in Murfreesboro, including 336 white gems, 73 brown, and 82 yellow, a news release said.<br /> <br /> The total weight for all diamonds registered last year was 99.14 carats -- 22 carats heavier than all diamonds found in 2018, it said.<br /> <br /> The average weight of diamond found last year was around 20 points, or one-fifth of a carat. Though most were found by wet sifting, a method that involves sorting large quantities of gravel by size and weight, about one in every 10 diamonds were found on top of the ground at the park, including many of the year's largest finds, the release said.<br /> <br /> Visitors found about one diamond per day in January and February 2019. As visitation picked up in March, so did the number of finds. One hundred and one diamonds had been registered by the first day of spring last year, but only one of these weighed more than a carat. March was the busiest month for park visitation, as well as diamond finds, with 71 diamonds registered during the month, it said.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> The rate of diamond finds remained fairly steady through spring and early summer, and heavy summer rains also brought heavier diamonds. By the end of July, park visitors had found 297 diamonds, including 10 weighing at least a carat. On July 24, Josh Lanik, of Hebron, Neb., found the first 2-carat-plus diamond of the year. Lanik found his 2.12-carat brandy-colored gem while surface searching near the West Drain of the park's diamond search area. He named it the "Lanik Family Diamond" in honor of an "unforgettable experience at Arkansas' diamond site," the release said.<br /> <br /> Three weeks later, Miranda Hollingshead, of Bogata, Texas, brought her family to the Crater of Diamonds after learning that the park is only a couple hours from her home. Hollingshead was sitting on the northeast side of the diamond search area on Aug. 16, watching a YouTube video about how to find diamonds, when she looked down and saw a 3.72-carat yellow diamond on top of the ground.<br /> <br /> "Hollingshead, a fan of superheroes, named her gem the 'Caro Avenger,'" the release said.<br /> <br /> To expose unsearched diamond-bearing material and create new opportunities for finds, in early fall the park conducted a trenching project along the south end of the search area. Shortly after the project wrapped up, longtime park visitors John and Pat Choate, of Jacksonville, registered their largest diamond find to date. While searching on Canary Hill in the search area on Oct. 22, Pat Choate found a 3.29-carat brown diamond on the surface of the plowed field. She named her gem the "Illusive Dream," calling it a "dream come true after many years of hard work searching for diamonds."<br /> <br /> By the end of last year, visitors had registered 18 diamonds weighing more than a carat at the park.<br /> <br /> "While most visitors don't find diamonds their first time here, experiences like these are bound to happen once in a while. It's the anticipation of the next diamond find that makes Crater of Diamonds State Park an exciting place to work at, and an even more exciting place to visit," the release said.<br /> <br /> <a href="https://www.geologyin.com/2016/08/the-only-diamond-mine-in-world-where.html" target="_blank">See:  The Only Diamond Mine In the World Where You Can Be the Miner</a><br /> <br /> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above post is reprinted from  <a href="https://www.hotsr.com/news/2020/jan/25/more-than-99-carats-of-arkansas-diamond/" rel="nofollow" target="_blank">The Sentinel-Record.</a></span></i></u></div>

More Than 99 Carats of Arkansas Diamonds Found at Park in 2019

Pat Choate, of Jacksonville, found a 3.29-carat brown diamond she named "Illusive Dream," calling it a dream come true after ma...

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Is Black Quartz Natural?

<div dir="ltr" style="text-align: left;" trbidi="on"> <div class="separator" style="clear: both; text-align: center;"> <a href="https://1.bp.blogspot.com/-_TOeKUOy2H0/XkgH6sfS5cI/AAAAAAAAR7E/jK5ycjhg1WIr0zAp193WIgMy1X6qILyewCLcBGAsYHQ/s1600/Is%2BBlack%2BQuartz%2BNatural%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="576" data-original-width="1073" height="342" src="https://1.bp.blogspot.com/-_TOeKUOy2H0/XkgH6sfS5cI/AAAAAAAAR7E/jK5ycjhg1WIr0zAp193WIgMy1X6qILyewCLcBGAsYHQ/s640/Is%2BBlack%2BQuartz%2BNatural%2B%25281%2529.jpg" width="640" /></a></div> <br /> Quartz may be the<b> second most common mineral</b> on our planet’s crust, but everyone from the ancient Egyptians and Australian Aborigines to modern-day New Age practitioners believe that this crystal holds mystical or healing properties.<br /> <br /> <b>Black quartz</b> is a <a href="https://www.geologyin.com/2016/04/major-varieties-of-quartz.html" target="_blank">variety of quartz </a>that ranges in clarity from almost complete transparency to an almost-opaque black crystal.<br /> <br /> Like other quartz gems, it is a <b>silicon dioxide</b> crystal. The smoky colour results from free silicon formed from the silicon dioxide by natural irradiation.<br /> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Color</span></h4> <div style="text-align: left;"> The color of smoky quartz is caused by irradiation and traces of aluminum built into its crystal lattice. Aluminum replaces silicon to form a [AlO₄]^- group instead of [SiO₄]. To compensate for the imbalance of charge in the lattice, small monovalent cations (H⁺, Li⁺ or Na⁺) are built into the lattice, as well. High energy radiation transfers the extra electron from [AlO₄]^- to the cation, and a color center is formed. Interestingly, H+ seems to interfere with this process, and higher concentrations of built-in hydrogen inhibit the formation of color-centers. In normal geological environments this process can only take place at temperatures below 50°C, otherwise the rate of color center destruction surpasses that of color center formation. So the color of the crystals appeared long after the crystals have grown. It is estimated that it takes several million years for a crystal to assume a deep color in a granite of average composition.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> True smoky quartz will lose its color when heated to about 200°C, and the color will occur again when the crystal is irradiated with x^- or gamma-rays.<br /> <br /> It's still common practice to <b>artificially </b>irradiate colorless quartz and sell it as smoky quartz.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Occurrence</span></h4> Smoky quartz is usually found in <b>intrusive igneous</b> and certain high grade metamorphic rocks, like granite and orthogneiss, as these contain traces of radioactive elements whose radiation cause the coloration.<br /> Smoky quartz from volcanic rocks is more <b>uncommon</b>, here amethyst and colorless quartz dominate.<br /> <br /> Smoky quartz from sedimentary rocks is very <b>unusual</b>. Their content of radioactive elements is usually very low. Much of the "smoky" quartz reported from sedimentary rocks is actually not true smoky quartz, but quartz containing black or brown <a href="https://www.geologyin.com/2017/01/types-of-mineral-inclusions-with-photos.html" target="_blank"><b>inclusions</b></a>.<br /> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Varieties</span></h4> <div style="text-align: left;"> <b>Cairngorm:</b> Synonym if Smoky Quartz. This term is used mostly in Scotland, specifically for the deposit in the Cairngorm Mountains where it is found.<br /> <b>Morion:</b>  Morion is a very dark brown to black opaque variety. Morion is the German, Danish, Spanish and Polish synonym for smoky quartz.<br /> <br /> <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://1.bp.blogspot.com/-0eYdUfmkDKc/XkgJqYJwPhI/AAAAAAAAR7Q/HjTXzF5aXhIbnFGsibbG_Hh18o02zm8XACLcBGAsYHQ/s1600/Morion%2Bvariety%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1080" data-original-width="1080" height="320" src="https://1.bp.blogspot.com/-0eYdUfmkDKc/XkgJqYJwPhI/AAAAAAAAR7Q/HjTXzF5aXhIbnFGsibbG_Hh18o02zm8XACLcBGAsYHQ/s320/Morion%2Bvariety%2B%25281%2529.jpg" width="320" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">Morion, a variety of smoky quartz<br /> Photo: Dario Crespi </td></tr> </tbody></table> <br /> <b>See also:</b><br /> <a href="https://www.geologyin.com/2017/06/how-is-aura-rainbow-quartz-made.html" target="_blank">How Is Aura Rainbow Quartz Made?</a><br /> <a href="https://www.geologyin.com/2018/07/what-causes-pink-color-of-rose-quartz.html" target="_blank">What Causes the Pink Color of Rose Quartz?</a><br /> <br /></div> </div>

Is Black Quartz Natural?

Quartz may be the second most common mineral on our planet’s crust, but everyone from the ancient Egyptians and Australian Aborigines ...

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New Research Reveals Violent Birth of Continent Zealandia

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-Xd4zN5fIn5c/XkVjhVqQFYI/AAAAAAAAR6U/q-UPkc7oGC40KO7_rWnkB03FrdBUf-u3QCLcBGAsYHQ/s1600/New%2BResearch%2BReveals%2BViolent%2BBirth%2Bof%2BContinent%2BZealandia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="828" data-original-width="1255" height="422" src="https://1.bp.blogspot.com/-Xd4zN5fIn5c/XkVjhVqQFYI/AAAAAAAAR6U/q-UPkc7oGC40KO7_rWnkB03FrdBUf-u3QCLcBGAsYHQ/s640/New%2BResearch%2BReveals%2BViolent%2BBirth%2Bof%2BContinent%2BZealandia.jpg" width="640" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">Continent Zealandia</td></tr> </tbody></table> <br /> <br /> <br /> Recent seafloor drilling has revealed that the "hidden continent " of Zealandia -- a region of continental crust twice the size of India submerged beneath the southwest Pacific Ocean -- experienced dramatic elevation changes between about 50 million and 35 million years ago. New findings from this expedition, published today in Geology, propose this topographic upheaval may have been due to a widespread reactivation of ancient faults linked to formation of the western Pacific's infamous Ring of Fire.<br /> <br /> Since the 1970s the prevailing scientific wisdom has been that Zealandia's unusually low profile is due to the thinning of its crust as it separated from Gondwana, the ancient supercontinent that included Antarctica and Australia, around 85 million years ago.<br /> <br /> After these tectonic fireworks, says Rupert Sutherland, a geophysicist at New Zealand's Victoria University of Wellington and the paper's lead author, this model has Zealandia "doing nothing but gently cooling and subsiding."<br /> <br /> But fossils in the drillcores collected in 2017 by International Ocean Discovery Program Expedition 371 indicate that during the early Cenozoic, portions of northern Zealandia rose 1-2 kilometers while other sections subsided about the same amount before the entire continent sank another kilometer deep underwater.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> The timing of these topographic transformations, say Sutherland and his co-authors, coincides with a global reorganization of tectonic plates evidenced by the bend in the Emperor-Hawaii seamount chain, the reorientation of numerous mid-ocean ridges, and the onset of subduction -- and the related volcanism and seismicity -- in a belt that still encircles much of the western Pacific.<br /> <br /> Although subduction drives Earth's plate tectonic cycle, says Sutherland, scientists don't yet understand how it starts. The drilling expedition to Zealandia may offer new insights into this fundamental process.<br /> <br /> "One of the amazing things about our observations," says Sutherland, "is that they reveal the early signs of the Ring of Fire were almost simultaneous throughout the western Pacific." Because this timing predates the global tectonic plate reorganization, he says, scientists need to find an explanation for how subduction began across such a broad area in such a short time.<br /> <br /> Sutherland and his co-authors propose a new mechanism: a 'subduction rupture event,' which they argue is similar to a massive, super-slow earthquake. The researchers believe the event resurrected ancient subduction faults that had lain dormant for many millions of years.<br /> <br /> "We don't know where or why," says Sutherland, "but something happened that locally induced movement, and when the fault started to slip, like in an earthquake the motion rapidly spread sideways onto adjacent parts of the fault system and then around the western Pacific."<br /> <br /> But unlike an earthquake, Sutherland says, the subduction rupture event may have taken more than a million years to unfold. "Ultimately," he says, "Zealandia's sedimentary record should help us determine how and why this event happened and what the consequences were for animals, plants, and global climate."<br /> <br /> The process has no modern analogue, according to Sutherland, and because the subduction rupture event is linked to a time of rapid, global plate tectonic change, other instances of such change in the geologic record may imply that comparable events have occurred in the past. "Geologists generally assume that understanding the present is the key to understanding the past," he says. "But at least in this instance, this may not hold."<br /> <br /> <br /> <br /> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.geosociety.org/GSA/News/pr/2020/20-03.aspx" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.geosociety.org/" rel="nofollow" target="_blank">Geological Society of America</a>.</span></i></u></div>

New Research Reveals Violent Birth of Continent Zealandia

Continent Zealandia Recent seafloor drilling has revealed that the "hidden continent " of Zealandia -- a region of contine...

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Oldest Record Of Primitive Bee With Pollen Dates Back 100 Million Years

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-UiMIarxqiC4/XkVzlAyCyhI/AAAAAAAAR6s/F_QwZUXQcuAjpurZ91axn1aeVCXb9YE4wCLcBGAsYHQ/s1600/100-million-year-old%2BDiscoscapa%2Bapicula.%2BThe%2Bbee%2Bis%2Bcarrying%2Bfour%2Bbeetle%2Btriungulins..jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt=" Oldest Record Of Primitive Bee With Pollen Dates Back 100 Million Years" border="0" data-original-height="724" data-original-width="1206" height="384" src="https://1.bp.blogspot.com/-UiMIarxqiC4/XkVzlAyCyhI/AAAAAAAAR6s/F_QwZUXQcuAjpurZ91axn1aeVCXb9YE4wCLcBGAsYHQ/s640/100-million-year-old%2BDiscoscapa%2Bapicula.%2BThe%2Bbee%2Bis%2Bcarrying%2Bfour%2Bbeetle%2Btriungulins..jpg" title="" width="640" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">100-million-year-old Discoscapa apicula. The bee is carrying four beetle triungulins. Credit: George Poinar Jr., OSU College of Science.</td></tr> </tbody></table> <span style="font-family: "georgia" , "times new roman" , serif;"><br /> </span> <span style="font-family: "georgia" , "times new roman" , serif;">Fossilised insect from 100 million years ago is oldest record of primitive bee with pollen</span><br /> <br /> <span style="font-family: "georgia" , "times new roman" , serif;">Beetle parasites clinging to a primitive bee 100 million years ago may have caused the flight error that, while deadly for the insect, is a boon for science today.</span><br /> In a paper published online in the journal Palaeodiversity, Oregon State University’s Professor George Poinar Jr. described a new family, genus and species of pollen-collecting bee found in a piece of 99-million-year-old amber (mid-Cretaceous period) excavated from a mine in Myanmar.<br /> The female bee, which became stuck in tree resin and thus preserved in amber, has been identified by Oregon State University researcher George Poinar Jr. as a new family, genus and species.<br /> <br /> The mid-Cretaceous fossil from Myanmar provides the first record of a primitive bee with pollen and also the first record of the beetle parasites, which continue to show up on modern bees today.<br /> <br /> The findings, published in BioOne Complete, shed new light on the early days of bees, a key component in evolutionary history and the diversification of flowering plants.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> Insect pollinators aid the reproduction of flowering plants around the globe and are also ecologically critical as promoters of biodiversity. Bees are the standard bearer because they're usually present in the greatest numbers and because they're the only pollinator group that feeds exclusively on nectar and pollen throughout their life cycle.<br /> <br /> Bees evolved from apoid wasps, which are carnivores. Not much is known, however, about the changes wasps underwent as they made that dietary transition.<br /> <br /> Poinar, professor emeritus in the OSU College of Science and an international expert in using plant and animal life forms preserved in amber to learn more about the biology and ecology of the distant past, classified the new find as Discoscapa apicula, in the family Discoscapidae.<br /> <br /> The fossilized bee shares traits with modern bees—including plumose hairs, a rounded pronotal lobe, and a pair of spurs on the hind tibia—and also those of apoid wasps, such as very low-placed antennal sockets and certain wing-vein features.<br /> <br /> "Something unique about the new family that's not found on any extant or extinct lineage of apoid wasps or bees is a bifurcated scape," Poinar said, referring to a two-segment antennae base. "The fossil record of bees is pretty vast, but most are from the last 65 million years and look a lot like modern bees. Fossils like the one in this study can tell us about the changes certain wasp lineages underwent as they became palynivores—pollen eaters."<br /> <br /> Numerous pollen grains on Discoscapa apicula show the bee had recently been to one or more flowers.<br /> <br /> "Additional evidence that the fossil bee had visited flowers are the 21 beetle triungulins—larvae—in the same piece of amber that were hitching a ride back to the bee's nest to dine on bee larvae and their provisions, food left by the female," Poinar said. "It is certainly possible that the large number of triungulins caused the bee to accidently fly into the resin."<br /> <br /> <br /> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://today.oregonstate.edu/news/fossilized-insect-100-million-years-ago-oldest-record-primitive-bee-pollen" rel="nofollow" target="_blank">materials </a>provided by <a href="https://oregonstate.edu/" rel="nofollow" target="_blank">Oregon State University</a>.</span></i></u></div>

Oldest Record Of Primitive Bee With Pollen Dates Back 100 Million Years

100-million-year-old Discoscapa apicula. The bee is carrying four beetle triungulins. Credit: George Poinar Jr., OSU College of Science. ...

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Biggest Turtle That Ever Lived Had 10 Foot Shell With Horns

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-FgoFNajsDuY/XkVnlIEm0uI/AAAAAAAAR6g/ftewisf9A4gmHtqiJUs37v9KK0RrB6r1QCLcBGAsYHQ/s1600/giantturtlewithhorns%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="739" data-original-width="1279" height="368" src="https://1.bp.blogspot.com/-FgoFNajsDuY/XkVnlIEm0uI/AAAAAAAAR6g/ftewisf9A4gmHtqiJUs37v9KK0RrB6r1QCLcBGAsYHQ/s640/giantturtlewithhorns%2B%25281%2529.jpg" width="640" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">The huge extinct freshwater turtle Stupendemys geographicus,  Palaeontologist Rodolfo Sanchez lies alongside a carapace of the giant turtle Stupendemys geographicus, from Urumaco, Venezuela. Photograph: University of Zurich/Edwin Cadena/PA</td></tr> </tbody></table> <br /> <b><span style="font-family: "georgia" , "times new roman" , serif;">Car-sized Turtle Fossils Unearthed </span></b><br /> Scientists have unearthed new fossils of one of the largest turtles that ever lived: a car-sized reptile which prowled the lakes and rivers of what is now northern South America from about 13m years ago to 7m years ago.<br /> <br /> <div style="text-align: left;"> The tropical region of South America is one of the world's hot spots when it comes to animal diversity. The region's extinct fauna is unique, as documented by fossils of giant rodents and crocodylians -including crocodiles, alligators, caimans and gavials -- that inhabited what is today a desert area in Venezuela. Five to ten million years ago, this was a humid swampy region teeming with life. One of its inhabitants was Stupendemys geographicus, a turtle species first described in the mid-1970s.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Giant turtle 100 times heavier than its closest relative</span></h4> <div style="text-align: left;"> Researchers of the University of Zurich (UZH) and fellow researchers from Colombia, Venezuela, and Brazil have now reported exceptional specimens of the extinct turtle recently found in new locations across Venezuela and Colombia. </div> <div style="text-align: left;"> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> <div style="text-align: left;"> "The carapace of some Stupendemys individuals reached almost three meters, making it one of the largest, if not the largest turtle that ever existed," says Marcelo Sánchez, director of the Paleontological Institute and Museum of UZH and head of the study. The turtle had an estimated body mass of 1,145 kg -- almost one hundred times that of its closest living relative, the big-headed Amazon river turtle.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Males carried horns on their carapace</span></h4> <div style="text-align: left;"> In some individuals, the complete carapace showed a peculiar and unexpected feature: horns. "The two shell types indicate that two sexes of Stupendemys existed -- males with horned shells, and females with hornless shells," concludes Sánchez. According to the paleobiologist, this is the first time that sexual dimorphism in the form of horned shells has been reported for any of the side-necked turtles, one of the two major groups of turtles world-wide.<br /> <br /> Despite its tremendous size, the turtle had natural enemies. In many areas, the occurrence of Stupendemys coincides with Purussaurus, the largest caimans. This was most likely a predator of the giant turtle, given not only its size and dietary preferences, but also as inferred by bite marks and punctured bones in fossil carapaces of Stupendemys.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Turtle phylogeny thoroughly revised</span></h4> <div style="text-align: left;"> Since the scientists also discovered jaws and other skeleton parts of Stupendemys, they were able to thoroughly revise the evolutionary relationships of this species within the turtle tree of life. "Based on studies of the turtle anatomy, we now know that some living turtles from the Amazon region are the closest living relatives," says Sánchez. Furthermore, the new discoveries and the investigation of existing fossils from Brazil, Colombia and Venezuela indicate a much wider geographic distribution of Stupendemys than previously assumed. The animal lived across the whole of the northern part of South America.</div> <div style="text-align: left;"> <br /> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.media.uzh.ch/en/Press-Releases/2020/Giant-Turtle.html" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.uzh.ch/" rel="nofollow" target="_blank">University of Zurich</a>.</span></i></u></div> </div> </div>

Biggest Turtle That Ever Lived Had 10 Foot Shell With Horns

The huge extinct freshwater turtle Stupendemys geographicus,  Palaeontologist Rodolfo Sanchez lies alongside a carapace of the giant turt...

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What Is Moss Agate?

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-2tmSR2PiQDo/Xj3ai1SB6TI/AAAAAAAAR5w/iGbmBFw2KX8gdXB31hr98jOyKXLbavW1QCLcBGAsYHQ/s1600/moss%2Bagate%2Bfrom%2BIndonesia%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="What Is Moss Agate?" border="0" data-original-height="851" data-original-width="1196" height="283" src="https://1.bp.blogspot.com/-2tmSR2PiQDo/Xj3ai1SB6TI/AAAAAAAAR5w/iGbmBFw2KX8gdXB31hr98jOyKXLbavW1QCLcBGAsYHQ/s400/moss%2Bagate%2Bfrom%2BIndonesia%2B%25281%2529.jpg" title="" width="400" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">moss agate from Indonesia</td></tr> </tbody></table> <br /> <br /> Moss Agate is not banded, and therefore not strictly an <a href="https://www.geologyin.com/2016/08/types-of-agate-with-photos.html" target="_blank">Agate </a>in scientific terms; but is included in the Agate family. Moss agate is a <b>semi-precious</b> gemstone formed from silicon dioxide. Agate is a variety of Chalcedony, a mineral of the Quartz family.<br /> <br /> It is clear to milky white, with dendritic inclusions of manganese or iron that has grown into patterns similar to moss or lichen. The field is a clear or milky-white quartz, and the included minerals are mainly oxides of manganese or iron.<br /> <br /> The alternative name " <b>Mocha stone</b>" Or "<b>Mocca Stone</b>" comes from the Arabian city of Mocha in Yemen, which was an ancient source for the gemstone. <br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> It is a form of chalcedony which <b>includes </b>minerals of a green colour embedded in the stone, forming filaments and other patterns suggestive of moss It is not a true form of agate, as it lacks agate's defining feature of concentric banding.<br /> <br /> Despite its name, moss agate does not contain <b>organic matter</b> and is usually formed from weathered volcanic rocks. The colors are formed due to trace amounts of metal present as an impurity, such as chrome or iron. The metals can make different colors depending on their valence (oxidation state).<br /> <br /> While moss agate isn't strictly an agate because it's not banded, the stone does have the same chemical composition and intriguing patterns of agate. Moss agate is a variety of chalcedony, belonging to the quartz family, and is often found as fragments from weathered volcanic rock formed in fissures or as pebbles rather than in traditional agate layering.<br /> <br /> The spreading moss-like <b>dendritic </b>inclusions you see in moss agate are mostly oxides of manganese or iron, and the colors vary depending on trace amounts of minerals or metals present, such as chrome. Some moss agate on the market can be dyed to improve overall color. Moss agate is chiefly found in India, Brazil, Uruguay, central Europe and the western United States.<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/2019/06/what-is-fire-agate.html" target="_blank">What is Fire Agate?</a></span><br /> <span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2019/07/what-is-crazy-lace-agate.html" target="_blank">What is Crazy Lace Agate?</a></span><br /> <span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2019/04/what-is-grape-agate.html" target="_blank">What Is Grape Agate?</a></span></div>

What Is Moss Agate?

moss agate from Indonesia Moss Agate is not banded, and therefore not strictly an Agate in scientific terms; but is included in the A...

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Towering Dinosaur With Radioactive Skull Identified in Utah

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-cIJdTXmdCFk/XjQUxb3KxQI/AAAAAAAAR5E/4G6GYeum3t4_kWqq4JeUfzwsQJ4JlSWxQCLcBGAsYHQ/s1600/radioactive%2Bskull%2Bidentified%2Bin%2BUtah%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="720" data-original-width="1280" height="360" src="https://1.bp.blogspot.com/-cIJdTXmdCFk/XjQUxb3KxQI/AAAAAAAAR5E/4G6GYeum3t4_kWqq4JeUfzwsQJ4JlSWxQCLcBGAsYHQ/s640/radioactive%2Bskull%2Bidentified%2Bin%2BUtah%2B%25281%2529.jpg" width="640" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">(Credits: Xinhua/Bao Dandan/IANS)</td></tr> </tbody></table> <br /> <span style="font-family: "georgia" , "times new roman" , serif;">The 155-million-year-old specimen was headless until a radiation detector located the skeleton's skull.</span><br /> <br /> <div style="text-align: left;"> A remarkable new species of meat-eating dinosaur has been unveiled at the Natural History Museum of Utah. Paleontologists unearthed the first specimen in early 1990s in Dinosaur National Monument in northeastern Utah. The huge carnivore inhabited the flood plains of western North America during the Late Jurassic Period, between 157-152 million years ago, making it the geologically oldest species of Allosaurus, predating the more well-known state fossil of Utah, Allosaurus fragilis. The newly named dinosaur Allosaurus jimmadseni, was announced today in the open-access scientific journal PeerJ.<br /> <br /> The species belongs to the allosauroids, a group of small to large-bodied, two-legged carnivorous dinosaurs that lived during the Jurassic and Cretaceous periods. Allosaurus jimmadseni, possesses several unique features, among them a short narrow skull with low facial crests extending from the horns in front of the eyes forward to the nose and a relatively narrow back of the skull with a flat surface to the bottom of the skull under the eyes. The skull was weaker with less of an overlapping field of vision than its younger cousin Allosaurus fragilis. Allosaurus jimmadseni evolved at least 5 million years earlier than fragilis, and was the most common and the top predator in its ecosystem. It had relatively long legs and tail, and long arms with three sharp claws. The name Allosaurus translates as "different reptile," and the second part, jimmadseni, honors Utah State Paleontologist James H. Madsen Jr.<br /> <br /> Following an initial description by Othniel C. Marsh in 1877, Allosaurus quickly became the best known -- indeed the quintessential -- Jurassic theropod. The taxonomic composition of the genus has long been a debate over the past 130 years. Paleontologists argue that there are anywhere between one and 12 species of Allosaurus in the Morrison Formation of North America. This study recognizes only two species -- A. fragilis and A. jimmadseni.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> "Previously, paleontologists thought there was only one species of Allosaurus in Jurassic North America, but this study shows there were two species -- the newly described Allosaurus jimmadseni evolved at least 5 million years earlier than its younger cousin, Allosaurus fragilis," said co-lead author Mark Loewen, research associate at the Natural History Museum of Utah, and associate professor in the Department of Geology and Geophysics at the University of Utah led the study. "The skull of Allosaurus jimmadseni is more lightly built than its later relative Allosaurus fragilis, suggesting a different feeding behavior between the two."<br /> <br /> George Engelmann of the University of Nebraska, Omaha initially discovered the initial skeleton of the new species within Dinosaur National Monument in 1990. In 1996, several years after the headless skeleton was collected, the radioactive skull belonging to the skeleton using a radiation detector by Ramal Jones of the University of Utah. Both skeleton and skull were excavated by teams from Dinosaur National Monument.<br /> <br /> "Big Al," another specimen belonging to the new species, was discovered in Wyoming on United States Bureau of Land Management (BLM) land in 1991 and is housed in the collections of the Museum of The Rockies in Bozeman, Montana. Previously thought to belong to Allosaurus fragilis, "Big Al" was featured in the BBC's 2001 "Walking with Dinosaurs: Ballad of Big Al" video. Over the last 30 years, crews from various museums have collected and prepared materials of this new species. Other specimens include "Big Al Two" at the Saurier Museum Aathal in Switzerland and Allosaurus material from the Dry Mesa Quarry of Colorado at Brigham Young University.<br /> <br /> Early Morrison Formation dinosaurs were replaced by some of the most iconic dinosaurs of the Late Jurassic<br /> <br /> Allosaurus jimmadseni lived on the semi-arid Morrison Formation floodplains of the interior of western North America. The older rocks of the Morrison Formation preserve a fauna of dinosaurs distinct from the iconic younger Morrison Formation faunas that include Allosaurus fragilis, Diplodocus and Stegosaurus. Paleontologists have recently determined that specimens of this new species of dinosaur lived in several places throughout the western interior of North America (Utah, Colorado and Wyoming).<br /> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Study summary</span></h4> Dinosaurs were the dominant members of terrestrial ecosystems during the Mesozoic. However, the pattern of evolution and turnover of ecosystems during the middle Mesozoic remains poorly understood. The authors report the discovery of the earliest member of the group of large-bodied allosauroids in the Morrison Formation ecosystem that was replaced by Allosaurus fragilis and illustrate changes acquired in the genus over time. The study includes an in-depth description of every bone of the skull and comparisons with the cranial materials of other carnivorous dinosaurs. Finally, the study recognizes just two species of Allosaurus in North America with Allosaurus fragilis replacing its earlier relative Allosaurus jimmadseni.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">Fact sheet: Major points of the paper</span></h4> <div style="text-align: left;"> </div> <ul style="text-align: left;"> <li>A remarkable new species of meat-eating dinosaur, Allosaurus jimmadseni, is described based on two spectacularly complete skeletons. The first specimen was unearthed in Dinosaur National Monument, in northeastern Utah.</li> <li>Allosaurus jimmadseni is distinguished by a number of unique features, including low crests running from above the eyes to the snout and a relatively narrow back of the skull with a flat surface to the bottom of the upper skull under the eyes. The skull was weaker with less of an overlapping field of vision than its younger cousin Allosaurus fragilis.</li> <li>At 155 million years old, Allosaurus jimmadseni is the geologically-oldest species of Allosaurus predating the more well-known State Fossil of Utah Allosaurus fragilis.</li> <li>Allosaurus jimmadseni was the most common and the top predator in its ecosystem. It had relatively long legs and tail, and long arms with three sharp claws.</li> </ul> <ul style="text-align: left;"></ul> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://unews.utah.edu/new-dinosaur/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.utah.edu/" rel="nofollow" target="_blank">University of Utah</a>.</span></i></u></div>

Towering Dinosaur With Radioactive Skull Identified in Utah

(Credits: Xinhua/Bao Dandan/IANS) The 155-million-year-old specimen was headless until a radiation detector located the skeleton's...

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'Dancing Dragon' Feathered Dinosaur Fossil Discovered in China

<div dir="ltr" style="text-align: left;" trbidi="on"> <br /> <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://1.bp.blogspot.com/-tpIc01CkqrU/Xi8OjiQu6uI/AAAAAAAAR4o/zhFOoN3U0eMfu-8AEWeECC84SSrLwRB_QCLcBGAsYHQ/s1600/Dancing%2BDragon%2BFeathered%2BDinosaur%2BFossil%2BDiscovered%2Bin%2BChina.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="667" data-original-width="1200" height="353" src="https://1.bp.blogspot.com/-tpIc01CkqrU/Xi8OjiQu6uI/AAAAAAAAR4o/zhFOoN3U0eMfu-8AEWeECC84SSrLwRB_QCLcBGAsYHQ/s640/Dancing%2BDragon%2BFeathered%2BDinosaur%2BFossil%2BDiscovered%2Bin%2BChina.jpg" width="640" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">(Poust et al., The Anatomical Record)</td></tr> </tbody></table> <br /> <span style="font-family: "georgia" , "times new roman" , serif;">A 120 million-year-old fossil is helping paleontologists bridge the 'phantom' evolutionary leap between feathered dinosaurs and modern birds.</span><br /> <br /> <div style="text-align: left;"> A new species of feathered dinosaur has been discovered in China, and described by American and Chinese authors and published today in the journal, The Anatomical Record.<br /> <br /> The one-of-a-kind specimen offers a window into what the earth was like 120 million years ago. The fossil preserves feathers and bones that provide new information about how dinosaurs grew and how they differed from birds.<br /> <br /> "The new dinosaur fits in with an incredible radiation of feathered, winged animals that are closely related to the origin of birds," said Dr. Ashley Poust, who analyzed the specimens while he was a student at Montana State University and during his time as a Ph.D. student at University of California, Berkeley. Poust is now postdoctoral researcher at the San Diego Natural History Museum.<br /> <br /> "Studying specimens like this not only shows us the sometimes-surprising paths that ancient life has taken, but also allows us to test ideas about how important bird characteristics, including flight, arose in the distant past."<br /> <br /> Scientists named the dinosaur Wulong bohaiensis. Wulong is Chinese for "the dancing dragon" and references the position of the beautifully articulated specimen.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">About the Discovery</span></h4> <div style="text-align: left;"> </div> The specimen was found more than a decade ago by a farmer in China, in the fossil-rich Jehol Province, and since then has been housed in the collection of The Dalian Natural History Museum in Liaoning, a northeastern Chinese province bordering North Korea and the Yellow Sea. The skeletal bones were analyzed by Poust alongside his advisor Dr. David Varricchio from Montana State University while Poust was a student there.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> Larger than a common crow and smaller than a raven, but with a long, bony tail which would have doubled its length, Wulong bohaiensis had a narrow face filled with sharp teeth. Its bones were thin and small, and the animal was covered with feathers, including a wing-like array on both its arms and legs and two long plumes at the end of its tail.<br /> <br /> This animal is one of the earliest relatives of Velociraptor, the famous dromaeosaurid theropod dinosaur that lived approximately 75 million years ago. Wulong's closest well-known relative would have been Microraptor, a genus of small, four-winged paravian dinosaurs.<br /> <br /> The discovery is significant not only because it describes a dinosaur that is new to science, but also because it shows connection between birds and dinosaurs.<br /> <br /> "The specimen has feathers on its limbs and tail that we associate with adult birds, but it had other features that made us think it was a juvenile," said Poust. To understand this contradiction, the scientists cut up several bones of the new dinosaur to examine under a microscope. This technique, called bone histology, is becoming a regular part of the paleontology toolbox, but it's still sometimes difficult to convince museums to let a researcher remove part of a nice skeleton. "Thankfully, our coauthors at the Dalian Natural History Museum were really forward thinking and allowed us to apply these techniques, not only to Wulong, but also to another dinosaur, a close relative that looked more adult called Sinornithosaurus."<br /> <br /> The bones showed that the new dinosaur was a juvenile. This means that at least some dinosaurs were getting very mature looking feathers well before they were done growing. Birds grow up very fast and often don't get their adult plumage until well after they are full sized. Showy feathers, especially those used for mating, are particularly delayed. And yet here was an immature dinosaur with two long feathers extending beyond the tip of the tail.<br /> <br /> "Either the young dinosaurs needed these tail feathers for some function we don't know about, or they were growing their feathers really differently from most living birds," explained Poust.<br /> <br /> An additional surprise came from the second dinosaur the scientists sampled; Sinornithosaurus wasn't done growing either. The bone tissue was that of an actively growing animal and it lacked an External Fundamental System: a structure on the outside of the bone that vertebrates form when they're full size. "Here was an animal that was large and had adult looking bones: we thought it was going to be mature, but histology proved that idea wrong. It was older than Wulong, but seems to have been still growing. Researchers need to be really careful about determining whether a specimen is adult or not. Until we learn a lot more, histology is really the most dependable way."<br /> <br /> In spite of these cautions, Poust says there is a lot more to learn about dinosaurs.<br /> <br /> "We're talking about animals that lived twice as long ago as T. rex, so it's pretty amazing how well preserved they are. It's really very exciting to see inside these animals for the first time."<br /> <h4> <span style="font-family: "georgia" , "times new roman" , serif;">About the Jehol Biota</span></h4> The area in which the specimen was found is one of the richest fossil deposits in the world. The Jehol biota is known for the incredible variety of animals that were alive at the time. It is also one of the earliest bird-rich environments, where birds, bird-like dinosaurs, and pterosaurs all shared the same habitat.<br /> <br /> "There was a lot of flying, gliding, and flapping around these ancient lakes," says Poust. "As we continue to discover more about the diversity of these small animals it becomes interesting how they all might have fit into the ecosystem." Other important changes were happening at the same time in the Early Cretaceous, including the spread of flowering plants. "It was an alien world, but with some of the earliest feathers and earliest flowers, it would have been a pretty one."<br /> <br /> <br /> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.sdnhm.org/pressroom/pressroom_details/new-dinosaur-discovered-in-china-shows-dinosaurs-grew-up-differently-from-birds/35/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.sdnhm.org/" rel="nofollow" target="_blank">San Diego Natural History Museum</a>.</span></i></u></div>

'Dancing Dragon' Feathered Dinosaur Fossil Discovered in China

(Poust et al., The Anatomical Record) A 120 million-year-old fossil is helping paleontologists bridge the 'phantom' evolution...

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Meteor Crater Discovered in Australia is World’s Oldest

<div dir="ltr" style="text-align: left;" trbidi="on"> <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://1.bp.blogspot.com/-mNjb0IsP-hg/XiylRG34RlI/AAAAAAAAR4c/0IQMQRfz1QwAUM-Z0rrZYZBa6jaT0jWRwCLcBGAsYHQ/s1600/meteorcrater%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="741" data-original-width="1024" height="288" src="https://1.bp.blogspot.com/-mNjb0IsP-hg/XiylRG34RlI/AAAAAAAAR4c/0IQMQRfz1QwAUM-Z0rrZYZBa6jaT0jWRwCLcBGAsYHQ/s400/meteorcrater%2B%25281%2529.jpg" width="400" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;">Meteor craters, such as this one in Arizona are difficult to age precisely because the sites tend to be poorly preserved because erosion and tectonic events such as earthquakes erase the geologic past</td></tr> </tbody></table> <br /> <div style="text-align: left;"> A crater in western Australia was formed by a meteor strike more than 2.2 billion years ago and is the world's oldest known impact site, new research published Wednesday shows.<br /> <br /> The study marks the first time that the Yarrabubba crater has been precisely dated, at 2.229 billion years old, and means it is 200 million years older than any similar site known on Earth.<br /> <br /> The revelation also raises the intriguing possibility that the massive impact could have significantly altered the Earth's climate, helping end a period of global "deep freeze".<br /> <br /> Scientists had long suspected that Yarrabubba, in a remote part of the outback, dated back several billion years.<br /> <br /> But dating ancient craters is not easy: the sites tend to be poorly preserved because erosion and tectonic events such as earthquakes have "progressively erased into the geologic past", the researchers wrote in their paper, published in the journal Nature Communications on Wednesday.<br /> <br /> And even where craters are still present, determining their age is complex.<br /> <br /> To date Yarrabubba precisely, the team hunted for evidence of "shock recrystallisation" in minerals at the site—essentially where the massive impact of the meteor had altered the structure of materials including zircon and monazite.</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">'SHRIMP dating'</span></h4> <div style="text-align: left;"> But finding that record in the minerals involved searching for microscopic grains, using a high-tech scanning process known as Sensitive High Resolution Ion Micro Probe or SHRIMP dating.<br /> <div style="margin: 0px auto; width: 100%;"> <script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><br /> <ins class="adsbygoogle" data-ad-client="ca-pub-1021498709184325" data-ad-format="fluid" data-ad-layout="in-article" data-ad-slot="6157425841" style="display: block; text-align: center;"></ins><br /> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script><br /></div> Once identified, uranium in the grains helped the scientists determine a precise date, which they found coincided with a period when the planet emerged from a global deep freeze known as "Snowball Earth".<br /> <br /> "Glacial deposits are absent from the rock record for around 400 million years after the Yarrabubba impact," Chris Kirkland, a professor at Curtin University's School of Earth and Planetary Sciences who was involved in the study, told AFP.<br /> <br /> "The impact fits within the context of Earth moving out of frigid conditions."<br /> <br /> The researchers theorise that when the meteor hit Yarrabubba, the site was covered with ice, like much of the rest of the Earth at the time.<br /> <br /> The massive strike, which created a crater around 70 kilometres (45 miles) in diameter, may have sent up to half a trillion tons of vaporised ice into the atmosphere, according to models run by the team.<br /> <br /> "If the impact occurred into an ice sheet then it would release lots of water vapour, which is an even more efficient greenhouse gas than carbon dioxide," lead author Timmons Erickson, of NASA's Johnson Space Center and Curtin's School of Earth and Planetary Sciences, told AFP.<br /> <br /> "That, in turn, may result in warming of the planet."</div> <h4 style="text-align: left;"> <span style="font-family: "georgia" , "times new roman" , serif;">'A thought experiment'</span></h4> <div style="text-align: left;"> That conclusion may raise some eyebrows.<br /> <br /> The researchers concede there is no proof for now that the site was covered in ice at the time, and large meteor strikes are more often associated with cooling events than atmospheric warming.<br /> <br /> "They don't have any evidence that there was a glacier at the site, so it's like a thought experiment, it's speculation," said Tim Barrows, a professor of environmental change at the University of Wollongong, who was not involved in the study.<br /> <br /> Erickson acknowledged that the idea was still speculative for now.<br /> <br /> "We hope it will prompt other researchers to investigate the role that an impact event may have on the Earth's climate during a Snowball scenario," he said.<br /> <br /> While Barrows cast doubt on the climate change theory, he praised the "extremely impressive dating", saying the technique could help shed new light on other poorly preserved impact sites.<br /> <br /> The research team said they hoped their findings would boost the search for clues in the sediment record about the effects of the Yarrabubba strike, as well as encourage more work on dating craters.<br /> <br /> "The only way to understand the tempo of impacts on Earth is to look back at the history and timing of the cratering record," said Kirkland.<br /> <br /> "This work shows that there are impacts preserved on old, highly eroded pieces of the planet."</div> <div style="text-align: left;"> <br /></div> <div style="text-align: left;"> <br /></div> <div style="text-align: left;"> <u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.nature.com/articles/s41467-019-13985-7" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.nasa.gov/" rel="nofollow" target="_blank">NASA</a>.</span></i></u></div> </div>

Meteor Crater Discovered in Australia is World’s Oldest

Meteor craters, such as this one in Arizona are difficult to age precisely because the sites tend to be poorly preserved because erosion ...

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