Geology In

Deepest Point of Earth's Continents Found in Antarctica

<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/--jHPw4A3K8U/XfPCXvkJ2bI/AAAAAAAARuk/ZUbMCG7E1PQ7CQlK04Tw1UDn7tDX8wctACLcBGAsYHQ/s1600/Deepest%2BPoint%2Bof%2BEarth%2527s%2BContinents%2BFound%2Bin%2BAntarctica%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="720" data-original-width="1272" height="362" src="https://1.bp.blogspot.com/--jHPw4A3K8U/XfPCXvkJ2bI/AAAAAAAARuk/ZUbMCG7E1PQ7CQlK04Tw1UDn7tDX8wctACLcBGAsYHQ/s640/Deepest%2BPoint%2Bof%2BEarth%2527s%2BContinents%2BFound%2Bin%2BAntarctica%2B%25281%2529.jpg" width="640" /></a></div>
<br />
<br />
<span style="font-family: "georgia" , "times new roman" , serif;">A trough beneath Denman Glacier is the deepest continent point in the world, measuring more than 2 miles beneath sea level.</span><br />
<br />
A University of California, Irvine-led team of glaciologists has unveiled the most accurate portrait yet of the contours of the land beneath Antarctica's ice sheet -- and, by doing so, has helped identify which regions of the continent are going to be more, or less, vulnerable to future climate warming.<br />
<br />
Highly anticipated by the global cryosphere and environmental science communities, the newly released Antarctica topography map, BedMachine, and related findings were published today in the journal Nature Geoscience.<br />
<br />
Among the most striking results of the BedMachine project are the discovery of stabilizing ridges that protect the ice flowing across the Transantarctic Mountains; a bed geometry that increases the risk of rapid ice melting in the Thwaites and Pine Island glaciers sector of West Antarctica; a bed under the Recovery and Support Force glaciers that is hundreds of meters deeper than previously thought, making those ice sheets more susceptible to retreat; and the world's deepest land canyon below Denman Glacier in East Antarctica.<br />
<br />
"There were lots of surprises around the continent, especially in regions that had not been previously mapped in great detail with radar," said lead author Mathieu Morlighem, UCI associate professor of Earth system science. "Ultimately, BedMachine Antarctica presents a mixed picture: Ice streams in some areas are relatively well-protected by their underlying ground features, while others on retrograde beds are shown to be more at risk from potential marine ice sheet instability."<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 new Antarctic bed topography product was constructed using ice thickness data from 19 different research institutes dating back to 1967, encompassing nearly a million line-miles of radar soundings. In addition, BedMachine's creators utilized ice shelf bathymetry measurements from NASA's Operation IceBridge campaigns, as well as ice flow velocity and seismic information, where available. Some of this same data has been employed in other topography mapping projects, yielding similar results when viewed broadly.<br />
<br />
"Using BedMachine to zoom into particular sectors of Antarctica, you find essential details such as bumps and hollows beneath the ice that may accelerate, slow down or even stop the retreat of glaciers," Morlighem said.<br />
<br />
Previous Antarctica mapping methods relying on radar soundings have been generally effective, with some limitations. As aircraft fly in a straight line over a region, wing-mounted radar systems emit a signal that penetrates glaciers and ice sheets and bounces back from the point at which the ice meets solid ground. Glaciologists then use interpolation techniques to fill in the areas between the flight tracks, but this has proven to be an incomplete approach, especially with swiftly flowing glaciers.<br />
<br />
Alternatively, BedMachine relies on the fundamental physics-based method of mass conservation to discern what lies between the radar sounding lines, utilizing highly detailed information on ice flow motion that dictates how ice moves around the varied contours of the bed. This technique was instrumental in the research team's conclusion regarding the true depth of the Denman trough.<br />
<br />
"Older maps suggested a shallower canyon, but that wasn't possible; something was missing," Morlighem said. "With conservation of mass, by combining existing radar survey and ice motion data, we know how much ice fills the canyon -- which, by our calculations, is 3,500 meters below sea level, the deepest point on land. Since it's relatively narrow, it has to be deep to allow that much ice mass to reach the coast."<br />
<br />
By basing its results on ice surface velocity in addition to ice thickness data from radar soundings, BedMachine is able to present a more accurate, high-resolution depiction of the bed topography. This methodology has been successfully employed in Greenland in recent years, transforming cryosphere researchers' understanding of ice dynamics, ocean circulation and the mechanisms of glacier retreat.<br />
<br />
Applying the same technique to Antarctica is especially challenging due to the continent's size and remoteness, but, Morlighem noted, BedMachine will help reduce the uncertainty in sea level rise projections from numerical models.<br />
<br />
He said that future bed topography mapping on land could be greatly enhanced by charting sea floor depth offshore and beneath floating ice, which is an area of active study right now. In the paper published today, Morlighem also suggests that the study of fast-flowing Antarctic ice sheets would benefit from soundings along flight tracks perpendicular to the flow direction, "especially upstream of the Academy and Support Force glaciers, along the Gould Coast near the Ross Ice Shelf, and along the Wilhelm II Coast between the Denman and Lambert glaciers."<br />
<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://news.uci.edu/2019/12/12/uci-led-team-releases-high-precision-map-of-antarctic-ice-sheet-bed-topography/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.uci.edu/" rel="nofollow" target="_blank">University of California - Irvine</a>.</span></i></u></div>

Deepest Point of Earth's Continents Found in Antarctica

A trough beneath Denman Glacier is the deepest continent point in the world, measuring more than 2 miles beneath sea level. A Univers...

Giant Penguins Gave Up Flight and Started Swimming 66 Million Years Ago

extinction, Fossils 7:26 PM

<div dir="ltr" style="text-align: left;" trbidi="on">
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-4ddrOmSOG3g/Xe_IDcIJdaI/AAAAAAAARuY/N8td-CZ8I7QYdvsNNzEIgwE_6wszwpaMgCLcBGAsYHQ/s1600/Giant%2BPenguins%2BGave%2BUp%2BFlight%2Band%2BStarted%2BSwimming%2B66%2BMillion%2BYears%2BAgo%2B%25281%2529%2B%25281%2529.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="When penguins ruled after dinosaurs died" border="0" data-original-height="788" data-original-width="1295" height="388" src="https://1.bp.blogspot.com/-4ddrOmSOG3g/Xe_IDcIJdaI/AAAAAAAARuY/N8td-CZ8I7QYdvsNNzEIgwE_6wszwpaMgCLcBGAsYHQ/s640/Giant%2BPenguins%2BGave%2BUp%2BFlight%2Band%2BStarted%2BSwimming%2B66%2BMillion%2BYears%2BAgo%2B%25281%2529%2B%25281%2529.jpeg" title="" width="640" /></a></div>
<br />
<br />
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">When Penguins Ruled After Dinosaurs Died</span></h4>
Penguins weren't always the petite, tuxedo-sporting birds we know and love today. Once, giant penguins the size of humans reigned supreme.<br />
<br />
What waddled on land but swam supremely in subtropical seas more than 60 million years ago, after the dinosaurs were wiped out on sea and land?<br />
<br />
Fossil records show giant human-sized penguins flew through Southern Hemisphere waters—along side smaller forms, similar in size to some species that live in Antarctica today.<br />
<br />
Now the newly described Kupoupou stilwelli has been found on the geographically remote Chatham Islands in the southern Pacific near New Zealand's South Island. It appears to be the oldest penguin known with proportions close to its modern relatives.<br />
<br />
It lived between 62.5 million and 60 million years ago at a time when there was no ice cap at the South Pole and the seas around New Zealand were tropical or subtropical.<br />
<br />
Flinders University Ph.D. palaeontology candidate and University of Canterbury graduate Jacob Blokland made the discovery after studying fossil skeletons collected from Chatham Island between 2006 and 2011.<br />
<br />
He helped build a picture of an ancient penguin that bridges a gap between extinct giant penguins and their modern relatives.<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>
"Next to its colossal human-sized cousins, including the recently described monster penguin Crossvallia waiparensis, Kupoupou was comparatively small—no bigger than modern King Penguins which stand just under 1.1 metres tall," says Mr Blokland, who worked with Professor Paul Scofield and Associate Professor Catherine Reid, as well as Flinders palaeontologist Associate Professor Trevor Worthy on the discovery.<br />
<br />
"Kupoupou also had proportionally shorter legs than some other early fossil penguins. In this respect, it was more like the penguins of today, meaning it would have waddled on land.<br />
<br />
"This penguin is the first that has modern proportions both in terms of its size and in its hind limb and foot bones (the tarsometatarsus) or foot shape."<br />
<br />
As published in the US journal Palaeontologica Electronica, the animal's scientific name acknowledges the Indigenous Moriori people of the Chatham Island (Rēkohu), with Kupoupou meaning 'diving bird' in Te Re Moriori.<br />
<br />
The discovery may even link the origins of penguins themselves to the eastern region of New Zealand—from the Chatham Island archipelago to the eastern coast of the South Island, where other most ancient penguin fossils have been found, 800km away.<br />
<br />
University of Canterbury adjunct Professor Scofield, Senior Curator of Natural History at the Canterbury Museum in Christchurch, says the paper provides further support for the theory that penguins rapidly evolved shortly after the period when dinosaurs still walked the land and giant marine reptiles swam in the sea.<br />
<br />
"We think it's likely that the ancestors of penguins diverged from the lineage leading to their closest living relatives—such as albatross and petrels—during the Late Cretaceous period, and then many different species sprang up after the dinosaurs were wiped out," Professor Scofield says<br />
<br />
"It's not impossible that penguins lost the ability to fly and gained the ability to swim after the extinction event of 66 million years ago, implying the birds underwent huge changes in a very short time. If we ever find a penguin fossil from the Cretaceous period, we'll know for sure."<br />
<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://palaeo-electronica.org/content/2019/2773-chatham-island-penguins" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.flinders.edu.au/" rel="nofollow" target="_blank">Flinders University.</a></span></i></u></div>

Giant Penguins Gave Up Flight and Started Swimming 66 Million Years Ago

When Penguins Ruled After Dinosaurs Died Penguins weren't always the petite, tuxedo-sporting birds we know and love today. Once...

Stormquakes: Powerful Storms Cause Seafloor Tremors

Earthquakes, Tectonic 8:24 PM

Stormquakes: Powerful Storms Cause Seafloor Tremors

Stormquakes offshore North America (shown as red circles) and seismic stations (shown as triangles) from 2006 to 2015. Some of the appare...

Over 800 Mammoth Bones Discovered in Massive Fossil Stash in Mexico

extinction, Fossils 8:30 PM

Over 800 Mammoth Bones Discovered in Massive Fossil Stash in Mexico

Mammoth skull and tusks found in the pitfall. Image: Edith Camacho, INAH. Archaeologists said Wednesday they have made the largest-eve...

Fossil of 99m-year-old Bird With Unusually Long Toes Found

amber, Fossils 7:43 PM

<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/-cOkiBP6B8tg/XeVEQeSUq2I/AAAAAAAARs8/F7mtreTfdN8uaEGa88sY6hGqZ4Ial_90QCLcBGAsYHQ/s1600/Fossil%2Bof%2B99m-year-old%2BBird%2BWith%2BUnusually%2BLong%2BToes%2BFound%2B%25282%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1001" data-original-width="1197" height="534" src="https://1.bp.blogspot.com/-cOkiBP6B8tg/XeVEQeSUq2I/AAAAAAAARs8/F7mtreTfdN8uaEGa88sY6hGqZ4Ial_90QCLcBGAsYHQ/s640/Fossil%2Bof%2B99m-year-old%2BBird%2BWith%2BUnusually%2BLong%2BToes%2BFound%2B%25282%2529.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This photograph shows a nearly 100-million-year-old bird foot 
featuring a very long toe preserved in amber. The specimen also contains
 the bird's left wing tip. Credit: Lida Xing</td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<br />
<span style="font-family: "georgia" , "times new roman" , serif;">The fossilised remains of a bizarre, ancient bird that had middle toes longer than its lower legs have been found in a lump of amber from Myanmar.</span><br />
<br />
Meet the ancient bird that had toes longer than its lower legs. Researchers have discovered a bird foot from 99 million years ago preserved in amber that had a hyper-elongated third toe. The study, published in the journal Current Biology, suggests that this bird might have used its toes to hook food out of tree trucks. This is the first time such a foot structure has been observed in birds, either extinct or living.<br />
<br />
"I was very surprised when I saw the amber," says first author Lida Xing at China University of Geosciences (Beijing). "It shows that ancient birds were way more diverse than we thought. They had evolved many different features to adapt to their environments."<br />
<br />
To study the Cretaceous period fossil, Xing and his colleagues scanned the amber with micro-CT and created a 3-D reconstruction of the foot. They found that the bird's third toe, measuring 9.8 millimeters, is 41 percent longer than its second toe and 20 percent longer than its tarsometatarsus, which is a bone in the lower legs of birds. The team compared the ratios with those of 20 other extinct birds from the same era and 62 living birds. No bird has a foot that resembles this one.<br />
<br />
The researchers named it Elektorornis chenguangi. Elektorornis means "amber bird," and it belongs to a group of extinct birds called Enantiornithes, the most abundant type of bird known from the Mesozoic era. It is thought that Enantiornithines became extinct during the Cretaceous-Paleogene extinction event about 66 million years ago, along with dinosaurs. They have no living descendants.<br />
<br />
Based on the fossil, the team estimates that the Elektorornis was smaller than a sparrow, and it was arboreal, meaning it spent most of its time in trees as opposed to on the ground or in water.<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>
"Elongated toes are something you commonly see in arboreal animals because they need to be able to grip these branches and wrap their toes around them," says co-author Jingmai O'Connor at the Chinese Academy of Sciences. "But this extreme difference in toe lengths, as far as we know, has never been seen before."<br />
<br />
The amber the foot was found in, measuring 3.5 centimeters long and weighing 5.5 grams, was discovered around 2014 in the Hukawng Valley of Myanmar. During the Mesozoic era, the valley was full of trees that produced resin, a gooey substance that oozes out of the tree bark. Plants and small animals, such as geckos and spiders, often get trapped in the resin and become fossilized with the amber after millions of years. Scientists have discovered many extinct animals, including the oldest known bee and a feathered dinosaur tail, in amber from this valley.<br />
<br />
Xing obtained the amber from a local amber trader, who didn't know what animal this weird foot belonged to.<br />
<br />
"Some traders thought it's a lizard foot, because lizards tend to have long toes," Xing says. "Although I've never seen a bird claw that looks like this before, I know it's a bird. Like most birds, this foot has four toes, while lizards have five."<br />
<br />
It remains unknown why the amber bird evolved such an unusual feature. The only known animal with disproportionally long digits is the aye-aye. The aye-aye is a lemur that uses its long middle fingers to fish larvae and insects out of tree trunks for food. Therefore, the researchers suggest Elektorornis might have used its toe for the same purpose.<br />
<br />
"This is the best guess we have," O'Connor says. "There is no bird with a similar morphology that could be considered a modern analog for this fossil bird. A lot of ancient birds were probably doing completely different things than living birds. This fossil exposes a different ecological niche that these early birds were experimenting as they evolved."<br />
<br />
Moving forward, the team hopes to extract the proteins and pigments from some feathers exposed on the surface of the amber. Xing says such data could help them better understand the bird's adaptation to the environment, such as whether it had camouflage plumage.<br />
<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(19)30691-8?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982219306918%3Fshowall%3Dtrue" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(19)30691-8?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982219306918%3Fshowall%3Dtrue" rel="nofollow" target="_blank">Cell Press.</a></span></i></u></div>

Fossil of 99m-year-old Bird With Unusually Long Toes Found

This photograph shows a nearly 100-million-year-old bird foot featuring a very long toe preserved in amber. The specimen also contains ...

Scientists Discover 'Ice Fossils' in a 4.6 Billion-Year-Old Meteorite Shard

Meteorite, NASA 8:10 PM

<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/-PqrVi1SNzHM/XeKht8DQUJI/AAAAAAAARsI/SH5zSj_tlmEh_Dw4AvimGQeNNfc_WHvNwCLcBGAsYHQ/s1600/Scientists%2BDiscover%2B%2527Ice%2BFossils%2527%2Bin%2Ba%2B4.6%2BBillion-Year-Old%2BMeteorite%2BShard%2B%25282%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="617" data-original-width="1216" height="324" src="https://1.bp.blogspot.com/-PqrVi1SNzHM/XeKht8DQUJI/AAAAAAAARsI/SH5zSj_tlmEh_Dw4AvimGQeNNfc_WHvNwCLcBGAsYHQ/s640/Scientists%2BDiscover%2B%2527Ice%2BFossils%2527%2Bin%2Ba%2B4.6%2BBillion-Year-Old%2BMeteorite%2BShard%2B%25282%2529.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">XCT slice images of equant samples of the Acfer 094 matrix</td></tr>
</tbody></table>
<br />
<br />
<span style="font-family: Georgia, "Times New Roman", serif;">A 4.6 billion-year-old meteorite landed in Algeria in 1990, the remnant of a larger asteroid born during the dawn of our solar system.</span><br />
<br />
New analysis of the meteorite, called Acfer 049, has revealed ice fossils trapped inside, making it the first direct evidence of frozen water as a building block of early asteroids.<br />
<br />
Given the meteorite's age, it also preserves material that created our solar system, providing a unique look at our corner of the universe and how it formed. The new findings published this month in the journal Science Advances.<br />
<br />
Scientists know that it was possible for asteroids to include ice as an ingredient in their structure, mainly due to the way water altered minerals in the asteroids. But they wanted to understand more about the amount of water, its distribution throughout the asteroid structure, called a matrix, and when it melted.<br />
<br />
Acfer 049 preserved tiny pockets that once contained the ice before it melted and researchers call these microscopic holes ice fossils.<br />
<br />
Like other solar systems, ours began with the formation of a star. The sun formed from a cloud of dust and gas and the leftover materials not used to create the star became the ingredients for the planets in our solar system. Then gas and elements formed into a flat planetary disk around the sun and that included hydrogen, ice, iron and silicates.<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>
Over time, the dust and elements stuck together, forming planets and other bodies, including asteroids. This is why asteroids and comets are considered to be the leftovers of material that formed the solar system.<br />
<br />
Ice, which could be found beyond the snow line of the planetary disk where solid water ice can form, was also included in the mix. The snow line existed in the disk at a distance from the star where its heat couldn't maintain liquid water.<br />
<br />
"This is starting material from which all the planets, including Earth, came from," said Epifanio Vaccaro, study author and Curator of Petrology at London's Natural History Museum. "The matrix of these meteorites is therefore thought to be the starting material from which all the planets formed."<br />
<br />
The rocky bits of dust and ice that became asteroids retained a pristine record of the ingredients that created them. But the planets formed by rearranging their ingredients through heat -- metals melted to form the core while silicates created a mantle and crust. This means that rocks found on Earth are quite different than the material found in asteroids.<br />
<br />
"When this happens, all the starting material that we had in the protoplanetary disk is gone as it went through the process of melting and recrystallisation," Epifanio said. "This means that if we want to understand what the dust was like as the solar system formed, we need to go back and grab some of the material that didn't go through this differentiation process. In some meteorites, we have that starting material preserved."<br />
<br />
While dust and ice doesn't sound like the solid foundation for a rocky asteroid, its matrix is tightly constructed because of how its materials came together.<br />
"The matrix itself is very fine-grained material that holds everything in the meteorite together," Epifanio said.<br />
<br />
But the matrix itself made the meteorite difficult to study because they didn't have the technology to peer through the fine grains until now. The researchers used microscopes with high spatial resolution, which allowed them to finally see the tiny pockets that once contained ice.<br />
<br />
These microscopes could be used to look at other meteorites and possibly find more evidence of ice fossils, the researchers said.<br />
<br />
"Based on this finding of asteroidial ice, we made a model that tells us how the asteroid grew and how the planets formed," Epifanio said. "We think that fluffy ice and dust particles came together into bigger bodies beyond the snow line, and then migrated inwards. As they did so, the ice started melting, leaving the fossils in its place."<br />
<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The research has been published in <a href="https://advances.sciencemag.org/content/5/11/eaax5078" rel="nofollow" target="_blank">Science Advances.</a></span></i></u></div>

Scientists Discover 'Ice Fossils' in a 4.6 Billion-Year-Old Meteorite Shard

XCT slice images of equant samples of the Acfer 094 matrix A 4.6 billion-year-old meteorite landed in Algeria in 1990, the remnant of...

Opalized Petrified Wood

Fossils 7:47 PM

Opalized Petrified Wood

Colorful crystal patterns are displayed in a cross-section of petrified wood in the Petrified Forest National Park, located in northeast ...

What Are Lost Continents, and Why Are We Discovering So Many?

Earth History, Geology, Tectonic 7:42 PM

<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/-nYPpy_7E9Ns/XdwDUYtwgNI/AAAAAAAARrw/hl7gsFGHw4M7ngtrcBungcyM5SrHgSXywCLcBGAsYHQ/s1600/What%2BAre%2BLost%2BContinents%252C%2Band%2BWhy%2BAre%2BWe%2BDiscovering%2BSo%2BMany%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="What Are Lost Continents, and Why Are We Discovering So Many?" border="0" data-original-height="720" data-original-width="1280" height="360" src="https://1.bp.blogspot.com/-nYPpy_7E9Ns/XdwDUYtwgNI/AAAAAAAARrw/hl7gsFGHw4M7ngtrcBungcyM5SrHgSXywCLcBGAsYHQ/s640/What%2BAre%2BLost%2BContinents%252C%2Band%2BWhy%2BAre%2BWe%2BDiscovering%2BSo%2BMany%2B%25281%2529.jpg" title="" width="640" /></a></div>
<br />
<br />
<div style="text-align: left;">
For most people, continents are Earth’s seven main large landmasses.<br />
<br />
But geoscientists have a different take on this. They look at the type of rock a feature is made of, rather than how much of its surface is above sea level.<br />
<br />
In the past few years, we’ve seen an increase in the discovery of lost continents. Most of these have been plateaus or mountains made of continental crust hidden from our view, below sea level.<br />
<br />
One example is Zealandia, the world’s eighth continent that extends underwater from New Zealand.<br />
<br />
Several smaller lost continents, called microcontinents, have also recently been discovered submerged in the eastern and western Indian Ocean.<br />
<br />
But why, with so much geographical knowledge at our fingertips, are we still discovering lost continents in the 21st century?</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">We may have found another</span></h4>
<div style="text-align: left;">
In August, we undertook a 28-day voyage on the research vessel RV Investigator to explore a possible lost continent in a remote part of the Coral Sea. The area is home to a large underwater plateau off Queensland, called the Louisiade Plateau, which represents a major gap in our knowledge of Australia’s geology.<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>
On one hand, it could be a lost continent that broke away from Queensland about 60 million years ago. Or it could have formed as a result of a massive volcanic eruption taking place around the same time. We’re not sure, because nobody had recovered rocks from there before - until now.<br />
<br />
We spent about two weeks collecting rocks from this feature, and recovered a wide variety of rock types from parts of the seafloor as deep as 4,500m.<br />
<br />
Most were formed through volcanic eruptions, but some show hints that continental rocks are hiding beneath. Lab work over the next couple of years will give us more certain answers.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Down to the details</span></h4>
<div style="text-align: left;">
There are many mountains and plateaus below sea level scattered across the oceans, and these have been mapped from space. They are the lighter blue areas you can see on Google Maps.<br />
<br />
However, not all submerged features qualify as lost continents. Most are made of materials quite distinct from what we traditionally think of as continental rock, and are instead formed by massive outpourings of magma.<br />
<br />
A good example is Iceland which, despite being roughly the size of New Zealand’s North Island, is not considered continental in geological terms. It’s made up mainly of volcanic rocks deposited over the past 18 million years, meaning it’s relatively young in geological terms.<br />
<br />
The only foolproof way to tell the difference between massive submarine volcanoes and lost continents is to collect rock samples from the deep ocean.<br />
<br />
Finding the right samples is challenging, to say the least. Much of the seafloor is covered in soft, gloopy sediment that obscures the solid rock beneath.<br />
<br />
We use a sophisticated mapping system to search for steep slopes on the seafloor, that are more likely to be free of sediment. We then send a metal rock-collecting bucket to grab samples.<br />
<br />
The more we explore and sample the depths of the oceans, the more likely we’ll be to discover more lost continents.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">The ultimate lost continent</span></h4>
<div style="text-align: left;">
Perhaps the best known example of a lost continent is Zealandia. While the geology of New Zealand and New Caledonia have been known for some time, it’s only recently their common heritage as part of a much larger continent (which is 95% underwater) has been accepted.<br />
<br />
This acceptance has been the culmination of years of painstaking research, and exploration of the geology of deep oceans through sample collection and geophysical surveys.<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>
New discoveries continue to be made.<br />
<br />
During a 2011 expedition, we discovered two lost continental fragments more than 1,000km west of Perth.<br />
<br />
The granite lying in the middle of the deep ocean there looked similar to what you would find around Cape Leeuwin, in Western Australia.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Other lost continents</span></h4>
<div style="text-align: left;">
However, not all lost continents are found hidden beneath the oceans.<br />
<br />
Some existed only in the geological past, millions to billions of years ago, and later collided with other continents as a result of plate tectonic motions.<br />
<br />
Their only modern-day remnants are small slivers of rock, usually squished up in mountain chains such as the Himalayas. One example is Greater Adria, an ancient continent now embedded in the mountain ranges across Europe.<br />
<br />
Due to the perpetual motion of tectonic plates, it’s the fate of all continents to ultimately reconnect with another, and form a supercontinent.<br />
<br />
But the fascinating life and death cycle of continents is the topic of another story.</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;">This article is republished from <a href="https://theconversation.com/au" rel="nofollow" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/what-are-lost-continents-and-why-are-we-discovering-so-many-126355" rel="nofollow" target="_blank">original </a>article.</span></i></u></div>
</div>

What Are Lost Continents, and Why Are We Discovering So Many?

For most people, continents are Earth’s seven main large landmasses. But geoscientists have a different take on this. They look at t...

Scientists Discover New Carbon as Hard as Diamonds

Diamonds, Researches 7:13 PM

<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/-dkapHVBNEBM/XdgIoayAzGI/AAAAAAAARrU/Z8rRCr607IEbhrsVKK6wCsZV6wj5SIvAACLcBGAsYHQ/s1600/Scientists%2BDiscover%2BNew%2BCarbon%2Bas%2BHard%2Bas%2BDiamonds.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="541" data-original-width="1000" height="346" src="https://1.bp.blogspot.com/-dkapHVBNEBM/XdgIoayAzGI/AAAAAAAARrU/Z8rRCr607IEbhrsVKK6wCsZV6wj5SIvAACLcBGAsYHQ/s640/Scientists%2BDiscover%2BNew%2BCarbon%2Bas%2BHard%2Bas%2BDiamonds.png" width="640" /></a></div>
<br />
<br />
Superhard materials can slice, drill and polish other objects. They also hold potential for creating scratch-resistant coatings that could help keep expensive equipment safe from damage.<br />
<br />
Now, science is opening the door to the development of new materials with these seductive qualities.<br />
<br />
Researchers have used computational techniques to identify 43 previously unknown forms of carbon that are thought to be stable and superhard -- including several predicted to be slightly harder than or nearly as hard as diamonds. Each new carbon variety consists of carbon atoms arranged in a distinct pattern in a crystal lattice.<br />
<br />
The study -- published in the journal npj Computational Materials -- combines computational predictions of crystal structures with machine learning to hunt for novel materials. The work is theoretical research, meaning that scientists have predicted the new carbon structures but have not created them yet.<br />
<br />
"Diamonds are right now the hardest material that is commercially available, but they are very expensive," says University at Buffalo chemist Eva Zurek. "I have colleagues who do high-pressure experiments in the lab, squeezing materials between diamonds, and they complain about how expensive it is when the diamonds break.<br />
<br />
"We would like to find something harder than a diamond. If you could find other materials that are hard, potentially you could make them cheaper. They might also have useful properties that diamonds don't have. Maybe they will interact differently with heat or electricity, for example."<br />
<br />
Zurek, PhD, a professor of chemistry in UB College of Arts and Sciences, conceived of the study and co-led the project with Stefano Curtarolo, PhD, professor of mechanical engineering and materials science at Duke University.<br />
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">The quest for hard materials</span></h4>
Hardness relates to a material's ability to resist deformation. As Zurek explains, it means that "if you try to indent a material with a sharp tip, a hole will not be made, or the hole will be very small."<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>
Scientists consider a substance to be superhard if it has a hardness value of over 40 gigapascals as measured through an experiment called the Vickers hardness test.<br />
<br />
All of the study's 43 new carbon structures are predicted to meet that threshold. Three are estimated to exceed the Vickers hardness of diamonds, but only by a little bit. Zurek also cautions that there is some uncertainty in the calculations.<br />
<br />
The hardest structures the scientists found tended to contain fragments of diamond and lonsdaleite -- also called hexagonal diamond -- in their crystal lattices. In addition to the 43 novel forms of carbon, the research also newly predicts that a number of carbon structures that other teams have described in the past will be superhard.<br />
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Speeding up discovery of superhard materials</span></h4>
The techniques used in the new paper could be applied to identify other superhard materials, including ones that contain elements other than carbon.<br />
<br />
"Very few superhard materials are known, so it's of interest to find new ones," Zurek says. "One thing that we know about superhard materials is that they need to have strong bonds. Carbon-carbon bonds are very strong, so that's why we looked at carbon. Other elements that are typically in superhard materials come from the same side of the periodic table, such as boron and nitrogen."<br />
<br />
To conduct the study, researchers used XtalOpt, an open-source evolutionary algorithm for crystal structure prediction developed in Zurek's lab, to generate random crystal structures for carbon. Then, the team employed a machine learning model to predict the hardness of these carbon species. The most promising hard and stable structures were used by XtalOpt as "parents" to spawn additional new structures, and so on.<br />
<br />
The machine learning model for estimating hardness was trained using the Automatic FLOW (AFLOW) database, a huge library of materials with properties that have been calculated. Curtarolo's lab maintains AFLOW and previously developed the machine learning model with Olexandr Isayev's group at the University of North Carolina at Chapel Hill.<br />
<br />
"This is accelerated material development. It's always going to take time, but we use AFLOW and machine learning to greatly accelerate the process," Curtarolo says. "The algorithms learn, and if you have trained the model well, the algorithm will predict the properties of a material -- in this case, hardness -- with reasonable accuracy."<br />
<br />
"You can take the best materials predicted using computational techniques and make them experimentally," says study co-author Cormac Toher, PhD, assistant research professor of mechanical engineering and materials science at Duke University.<br />
<br />
The first and second authors of the new study are UB PhD graduate Patrick Avery and UB PhD student Xiaoyu Wang, both in Zurek's lab. In addition to these researchers, Zurek, Curtarolo and Toher, the co-authors of the paper include Corey Oses and Eric Gossett of Duke University and Davide Proserpio of the Universitá degi Studi di Milano.<br />
<br />
The research was funded by the U.S. Office of Naval Research, with additional support from the Universitá degi Studi di Milano, and computational support from UB's Center for Computational Research.<br />
<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://www.buffalo.edu/news/releases/2019/002/007.html" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.buffalo.edu/" rel="nofollow" target="_blank">University at Buffalo</a>. Original written by Charlotte Hsu.</span></i></u></div>

Scientists Discover New Carbon as Hard as Diamonds

Superhard materials can slice, drill and polish other objects. They also hold potential for creating scratch-resistant coatings that co...