January 2017

How Salt Crystals Destroy Stone Buildings

Crystal, Geology, Researches, sedimentary 4:33 PM

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<tr><td class="tr-caption" style="text-align: center;">Salt crystals </td></tr>
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<i><span style="font-family: "georgia" , "times new roman" , serif;">Salt crystals are often responsible when buildings start to show signs of ageing. Researchers from the Institute for Building Materials have studied salt damage in greater depth and can now predict weathering processes more accurately.</span></i><br />
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Tourists flock to historical stone buildings, such as the Jordanian rock city of Petra, the medieval town of Rhodes in the Aegean Sea, and the sandstone temples at Luxor, Egypt.<br />
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These cultural assets all have one thing in common: they suffer from weathering caused by salts, which crystallize inside the porous building materials and generate enough force for the stone to break or crumble. The same problem can also occur in concrete buildings.<br />
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Researchers have conducted an experiment to test the effect of salts under controlled conditions. They are hoping the results will help conservators and restorers of cultural assets predict the weathering process of buildings.<br />
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Salt can enter building materials in a variety of ways, explains Francesco Caruso, a postdoctoral researcher in the group of Robert Flatt, professor of building materials at ETH Zurich.<br />
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Cement, for example, a component of concrete, always contains gypsum (calcium sulfate) and alkali sulfates, both of which are salts.<br />
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Building materials can also be infiltrated by salt from the environment, such as through mineralized ground water close to the surface, which permeates porous building materials through capillary force, or via the atmospheric pollutant sulfur dioxide, which reacts with the calcium carbonate in limestone to form gypsum.<br />
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Damage can also be caused by de-icing salt and seawater spray that accumulates on the surface of buildings. “If these salts are dissolved by rain, the saline liquid can enter the building material through pores and cracks,” explains Caruso. The salts crystallize as the liquid dries out and evaporates, causing parts of the stonework to crumble away.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Supersaturated ‘destruction’</span></b><br />
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For their laboratory experiment, the researchers used sodium sulfate, the most destructive salt known, which exists in two forms: anhydrous and hydrated.<br />
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In several cycles, the researchers placed limestone cubes with a side length of two centimeters into a sodium sulfate salt bath, allowing the salt solution to permeate the pores of the limestone. They then dried the stones at high temperature before placing them in the salt bath again at a lower temperature for the next cycle.<br />
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During the drying phases, the salt crystallized in the stone’s pores in anhydrous form. In the salt bath phases, the salt solution permeated the pores again and the crystallized salt turned back into a liquid solution.<br />
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With this controlled cyclical process, the scientists managed to accumulate a large amount of salt within the stone and create a supersaturated salt solution with respect to the hydrated form. A supersaturated salt solution is a liquid in which, because of special circumstances, more salt is dissolved than would be possible under normal circumstances.<br />
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The experiment showed that the greater the supersaturation, the greater the salt’s destructive potential. Temperature also played a role: in cycles in which the temperature never fell below 25 ˚C (77˚ F), it took an average of four cycles before damage occurred.<br />
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When the temperature dropped to 3˚ C (37˚ F), one cycle was enough. “Although these wet and dry cycles play a part, supersaturation is the most important factor,” explains Caruso.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Predicting the damage</span></b><br />
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For a building, this means that if environmental conditions are such that a salt solution repeatedly infiltrates porous stone and the fluid can then evaporate again (e.g. due to strong sunlight or wind), the salt in the building material can become supersaturated.<br />
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“In these cases, it doesn’t take a lot of salt to inflict considerable damage,” says Flatt. However, higher amounts of salt are needed in more moderate environmental conditions.<br />
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With this controlled experiment, the researchers have been able to describe the phenomena of salt damage in detailed physico-chemical and mechanical terms for the first time.<br />
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“We have shown that damage caused by salt can be predicted, at least under controlled conditions,” says Flatt. The findings appear in Nature Communications.<br />
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He believes the experiments may help conservation scientists decide how much salt needs to be removed from a building to avoid damage or—if the salt cannot be removed—to predict when a building might be damaged.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Salt and the Sistine Chapel</span></b><br />
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This damage caused by salt is not seen only on historic buildings. It is also a problem for wall paintings, such as Michelangelo’s frescos inside the Sistine Chapel in the Vatican, says Caruso. These can be damaged by salt efflorescence in the stonework or the paint layers or in between.<br />
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The problem is also visible on a large scale in erosion processes and during geothermal drilling. “Salt damage forms entire rock landscapes,” says Caruso. In 2007, geothermal drilling in the old town of Stauffen, Germany, raised the ground by up to 26 centimeters in places, causing cracks to appear in rows of houses.<br />
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It was later discovered that due to the underground drilling, groundwater had entered a layer containing calcium sulfate in anhydrous form, which reacted with the water to form gypsum. The supersaturation of this gypsum generated enough pressure to lift the ground.<br />
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The researchers are now planning to use their findings in a project in Havana’s old town, where salt is a major issue. The special render used in restoration work crumbles away from building façades after just a few years, and the aim of the research project is to discover the exact cause.<br />
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The scientists involved in this research, from ETH Zurich as well as Princeton University, are also hoping to find ways to reduce salt damage, such as by changing the pores of building materials on a molecular scale.<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above post is reprinted from <a href="http://dx.doi.org/10.1038/ncomms5823" rel="nofollow" target="_blank">Materials </a>provided by <span id="goog_1663338715"></span><a href="https://www.ethz.ch/en/news-and-events/eth-news/news/2014/09/how-salt-causes-buildings-to-crumble.html" rel="nofollow" target="_blank">ETH Zurich</a>.</span></i></u></div>

How Salt Crystals Destroy Stone Buildings

Salt crystals Salt crystals are often responsible when buildings start to show signs of ageing. Researchers from the Institute f...

Fossilized Tree and Ice Cores Help Date Huge Volcanic Eruption

Earth History, Geochemistry, volcano 5:07 PM

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<i><span style="font-family: "georgia" , "times new roman" , serif;">An international team of researchers has managed to pinpoint, to within three months, a medieval volcanic eruption in east Asia the precise date of which has puzzled historians for decades. They have also shown that the so-called "Millennium eruption" of Changbaishan volcano, one of the largest in history, cannot have brought about the downfall of an important 10th century kingdom, as was previously thought.</span></i><br />
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Writing in the journal Quaternary Science Reviews the team describes how new analysis of the partly fossilised remains of a tree killed by the eruption, and ice cores drilled in Greenland, lead them to conclude the eruption occurred in the final months of 946 AD.<br />
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The volcano, also known as Mount Paektu, is located on the border between China and North Korea. The team of researchers, led by Dr. Clive Oppenheimer from the University of Cambridge's Department of Geography, set out to establish an accurate date for the event by making new radiocarbon measurements on a fossilised larch trunk recovered from the Chinese side of the volcano. The tree was 264 years old when it was killed and buried by a flow of larva, hot ashand pumice.<br />
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Armed with new information, the modern-day time detectives set about ascertaining when this could have happened. They reckoned the tree would have been standing in 775, a year that was marked by a burst of cosmic rays reaching the Earth. Evidence of this event, in the shape of radiocarbon, was found in one of the tree's rings and by counting to the outer ring, the team was able to work out when the tree must have perished. Further analysis indicates it had stopped its seasonal growth suggesting Autumn or Winter as the likely time of its demise.<br />
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By cross-referencing with ash deposits found in ice cores drilled in northern Greenland, the team could narrow down the calculation to the last 2 or 3 months of 946 AD.<br />
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Lead author, Dr Oppenheimer says: "The Millennium eruption has fascinated scientists and historians for decades because of its size, potential worldwide impacts, and the mystery surrounding when it actually happened. Lacking a clear historical record of the event, there have been dozens of attempts to date the eruption using conventional tree ring techniques. We got lucky thanks to the burst of cosmic radiation that bathed the Earth in the year 775. It was only recently recognised that this left a worldwide signature in trees alive at the time. Now we have a secure date for the eruption at last, we can be more confident in investigating the effects it has on the climate, environment and society."<br />
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Previous attempts to date the eruption had led historians to scan medieval texts for clues. Some argued the event led to the collapse of the Bohai kingdom (698-925 AD), however the findings now prove this predated the eruption. The kingdom spanned a vast area of what was then eastern Manchuria and northern Korea. The new date focuses attention instead on a chronicle from a temple in Japan that reports "white ash falling like snow" on the 3rd November 946 AD. This site is not near any of Japan's active volcanoes, and is close to where ash from the Millennium eruption has recently been identified in lake sediments. It may well pinpoint the actual date of the eruption since it would only have taken the ash clouds a day or so to reach Japan.<br />
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Changbaishan is a site revered by the Koreans. It is steeped in folklore and Koreans see it as their spiritual and ancestral home. Its eruption in 946 was one of the most violent of the last two thousand years and is thought to have discharged around 100 cubic kilometres of ash and pumice into the atmosphere -- enough to bury the entire UK knee deep.<br />
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<i><u><span style="font-family: "Trebuchet MS", sans-serif;">The above post is reprinted from <a href="http://www.cam.ac.uk/research/news/fossilised-tree-and-ice-cores-help-date-huge-volcanic-eruption-1000-years-ago-to-within-three-months" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.cam.ac.uk/" rel="nofollow" target="_blank">University of Cambridge</a>. </span></u></i><span style="background-color: white; color: #333333; display: inline; float: none; font-family: "helvetica neue" , "helvetica" , "arial" , sans-serif; font-size: 14px; font-style: normal; font-weight: normal; letter-spacing: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span class="Apple-converted-space"><br />
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Fossilized Tree and Ice Cores Help Date Huge Volcanic Eruption

An international team of researchers has managed to pinpoint, to within three months, a medieval volcanic eruption in east Asia the pre...

Scientists Create A New Kind Of Matter: Time Crystals

Crystal, Researches 3:10 PM

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<tr><td class="tr-caption" style="text-align: center;">Hoarfrost is a kind of ice crystal made of water.</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Researchers discovered time crystals, which are repetitive patterns that can move without a source of energy</span></b></h4>
<i><span style="font-family: "georgia" , "times new roman" , serif;">Physicists repeatedly tweaked a group of ions to create first example of a non-equilibrium material</span></i><br />
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<i><span style="font-family: "georgia" , "times new roman" , serif;">To most people, crystals mean diamond bling, semiprecious gems or perhaps the jagged amethyst or quartz crystals beloved by collectors.</span></i><br />
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Now it's official - researchers have just reported in detail how to make and measure these bizarre crystals. And two independent teams of scientists claim they've actually created time crystals in the lab based off this blueprint, confirming the existence of an entirely new form of matter.<br />
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The discovery might sound pretty abstract, but it heralds in a whole new era in physics - for decades we've been studying matter that's defined as being 'in equilibrium', such as metals and insulators.<br />
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But it's been predicted that there are many more strange types of matter out there in the Universe that aren't in equilibrium that we haven't even begun to look into, including time crystals. And now we know they're real.<br />
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The fact that we now have the first example of non-equilibrium matter could lead to breakthroughs in our understanding of the world around us, as well as new technology such as quantum computing. <br />
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"This is a new phase of matter, period, but it is also really cool because it is one of the first examples of non-equilibrium matter," said lead researcher Norman Yao from the University of California, Berkeley.<br />
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"For the last half-century, we have been exploring equilibrium matter, like metals and insulators. We are just now starting to explore a whole new landscape of non-equilibrium matter."<br />
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Let's take a step back for a second, because the concept of time crystals has been floating around for a few years now. <br />
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First predicted by Nobel-Prize winning theoretical physicist Frank Wilczek back in 2012, time crystals are structures that appear to have movement even at their lowest energy state, known as a ground state.<br />
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Usually when a material is in ground state, also known as the zero-point energy of a system, it means movement should theoretically be impossible, because that would require it to expend energy.<br />
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But Wilczek predicted that this might not actually be the case for time crystals.<br />
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Normal crystals have an atomic structure that repeats in space - just like the carbon lattice of a diamond. But, just like a ruby or a diamond, they're motionless because they're in equilibrium in their ground state.<br />
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But time crystals have a structure that repeats in time, not just in space. And it keep oscillating in its ground state. <br />
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Imagine it like jelly - when you tap it, it repeatedly jiggles. The same thing happens in time crystals, but the big difference here is that the motion occurs without any energy.<br />
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A time crystal is like constantly oscillating jelly in its natural, ground state, and that's what makes it a whole new form of matter - non-equilibrium matter. It's incapable of sitting still.<br />
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But it's one thing to predict these time crystals exist, it's another entirely to make them, which is where the new study comes in.<br />
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Yao and his team have now come up with a detailed blueprint that describes exactly how to make and measure the properties of a time crystal, and even predict what the various phases surrounding the time crystals should be - which means they've mapped out the equivalent of the solid, liquid, and gas phases for the new form of matter.<br />
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Published in Physical Review Letters, Yao calls the paper "the bridge between the theoretical idea and the experimental implementation".<br />
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And it's not just speculation, either. Based on Yao's blueprint, two independent teams - one from the University of Maryland and one from Harvard - have now followed the instructions to create their own time crystals. <br />
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Both of these developments were announced at the end of last year on the pre-print site arXiv.org (here and here), and have been submitted for publication in peer-reviewed journals. Yao is a co-author on both articles.<br />
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While we're waiting for the papers to be published, we need to be skeptical about the two claims. But the fact that two separate teams have used the same blueprint to make time crystals out of vastly different systems is promising.<br />
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The University of Maryland's time crystals were created by taking a conga line of 10 ytterbium ions, all with entangled electron spins.<br />
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The key to turning that set-up into a time crystal was to keep the ions out of equilibrium, and to do that the researchers alternately hit them with two lasers. One laser created a magnetic field and the second laser partially flipped the spins of the atoms.<br />
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Because the spins of all the atoms were entangled, the atoms settled into a stable, repetitive pattern of spin flipping that defines a crystal.<br />
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That was normal enough, but to become a time crystal, the system had to break time symmetry. And observing the ytterbium atom conga line, the researchers noticed it was doing something odd.<br />
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The two lasers that were periodically nudging the ytterbium atoms were producing a repetition in the system at twice the period of the nudges, something that couldn't occur in a normal system.<br />
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"Wouldn't it be super weird if you jiggled the Jell-O and found that somehow it responded at a different period?" said Yao.<br />
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"But that is the essence of the time crystal. You have some periodic driver that has a period 'T', but the system somehow synchronises so that you observe the system oscillating with a period that is larger than 'T'."<br />
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Under different magnetic fields and laser pulsing, the time crystal would then change phase, just like an ice cube melting.<br />
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The Harvard time crystal was different. The researchers set it up using densely packed nitrogen vacancy centres in diamonds, but with the same result. <br />
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"Such similar results achieved in two wildly disparate systems underscore that time crystals are a broad new phase of matter, not simply a curiosity relegated to small or narrowly specific systems," explained Phil Richerme from Indiana University, who wasn't involved in the study, in a perspective piece accompanying the paper.<br />
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"Observation of the discrete time crystal... confirms that symmetry breaking can occur in essentially all natural realms, and clears the way to several new avenues of research."<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">Yao's blueprint has been published in <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.030401" rel="nofollow" target="_blank">Physical Review Letters</a>, and you can see the Harvard time crystal paper <a href="https://arxiv.org/pdf/1610.08057v1.pdf" rel="nofollow" target="_blank">here</a>, and the University of Maryland paper <a href="https://arxiv.org/pdf/1609.08684v1.pdf" rel="nofollow" target="_blank">here</a>.</span></i></u></div>

Scientists Create A New Kind Of Matter: Time Crystals

Hoarfrost is a kind of ice crystal made of water. Researchers discovered time crystals, which are repetitive patterns that can move w...

Answering the Mystery of Turquoise Provenance

Mineralogy, Minerals 3:10 PM

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Turquoise has had cultural significance for Native American peoples in the southwestern United States and Mexico for more than a millennium, and turquoise artifacts have been recovered from archaeological sites hundreds of kilometers distant from known sources of the mineral. <br />
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Evidence for pre-Hispanic turquoise mining has been recognized across much of the southwestern United States and northern Mexico, including as far north as Leadville, Colorado, and as far south as Zacatecas.<br />
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Detailed archaeological studies of ancient turquoise mines are rare, and little is known about the timing of their exploitation or the cultural identities of the miners In this study, Alyson M. <br />
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Thibodeau and colleagues show that many geological sources of turquoise in the southwestern U.S. and northern Mexico can be distinguished from each other through the measurement of lead and strontium isotopic ratios. These isotopic analyses thus provide a new way to investigate the mining and movement of this mineral in prehistory.<br />
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<br />
<u><span style="font-family: "trebuchet ms" , sans-serif;"><i>The above story is based on <a href="http://www.geosociety.org/news/pr/2015/15-42.htm">materials</a> provided by <a href="http://www.geosociety.org/">Geological Society of America</a>.</i></span></u><span style="box-sizing: border-box; color: black; font-family: "verdana" , "geneva" , sans-serif; font-size: 14px; font-style: normal; font-weight: normal; letter-spacing: normal; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><br style="box-sizing: border-box;" /></span></div>

Answering the Mystery of Turquoise Provenance

Turquoise has had cultural significance for Native American peoples in the southwestern United States and Mexico for more than a millen...

Scientists Have Finally Created Metallic Hydrogen

News, Researches 3:48 PM

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<tr><td class="tr-caption" style="text-align: center;">Diamond anvils being used to put pressure on hydrogen sample</td></tr>
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<b><i><span style="font-family: "georgia" , "times new roman" , serif;">Lab-Made 'Metallic Hydrogen' Could Revolutionize Rocket Fuel</span></i></b><br />
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<i><span style="font-family: "georgia" , "times new roman" , serif;">Nearly a century after it was theorized, Harvard scientists have succeeded in creating the rarest - and potentially one of the most valuable - materials on the planet.</span></i><br />
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The material - atomic metallic hydrogen - was created by Thomas D. Cabot Professor of the Natural Sciences Isaac Silvera and post-doctoral fellow Ranga Dias. In addition to helping scientists answer fundamental questions about the nature of matter, the material is theorized to have a wide range of applications, including as a room-temperature superconductor. The creation of the rare material is described in a January 26 paper published in Science.<br />
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"This is the holy grail of high-pressure physics," Silvera said. "It's the first-ever sample of metallic hydrogen on Earth, so when you're looking at it, you're looking at something that's never existed before."<br />
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To create it, Silvera and Dias squeezed a tiny hydrogen sample at 495 gigapascal, or more than 71.7 million pounds-per-square inch - greater than the pressure at the center of the Earth. At those extreme pressures, Silvera explained, solid molecular hydrogen -which consists of molecules on the lattice sites of the solid - breaks down, and the tightly bound molecules dissociate to transforms into atomic hydrogen, which is a metal.<br />
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While the work offers an important new window into understanding the general properties of hydrogen, it also offers tantalizing hints at potentially revolutionary new materials.<br />
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"One prediction that's very important is metallic hydrogen is predicted to be meta-stable," Silvera said. "That means if you take the pressure off, it will stay metallic, similar to the way diamonds form from graphite under intense heat and pressure, but remains a diamond when that pressure and heat is removed."<br />
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Understanding whether the material is stable is important, Silvera said, because predictions suggest metallic hydrogen could act as a superconductor at room temperatures.<br />
"That would be revolutionary," he said. "As much as 15 percent of energy is lost to dissipation during transmission, so if you could make wires from this material and use them in the electrical grid, it could change that story."<br />
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Among the holy grails of physics, a room temperature superconductor, Dias said, could radically change our transportation system, making magnetic levitation of high-speed trains possible, as well as making electric cars more efficient and improving the performance of many electronic devices.<br />
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The material could also provide major improvements in energy production and storage - because superconductors have zero resistance energy could be stored by maintaining currents in superconducting coils, and then be used when needed.<br />
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Though it has the potential to transform life on Earth, metallic hydrogen could also play a key role in helping humans explore the far reaches of space, as the most powerful rocket propellant yet discovered.<br />
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"It takes a tremendous amount of energy to make metallic hydrogen," Silvera explained. "And if you convert it back to molecular hydrogen, all that energy is released, so it would make it the most powerful rocket propellant known to man, and could revolutionize rocketry."<br />
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The most powerful fuels in use today are characterized by a "specific impulse" - a measure, in seconds, of how fast a propellant is fired from the back of a rocket - of 450 seconds. The specific impulse for metallic hydrogen, by comparison, is theorized to be 1,700 seconds.<br />
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"That would easily allow you to explore the outer planets," Silvera said. "We would be able to put rockets into orbit with only one stage, versus two, and could send up larger payloads, so it could be very important."<br />
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To create the new material, Silvera and Dias turned to one of the hardest materials on Earth - diamond.<br />
But rather than natural diamond, Silvera and Dias used two small pieces of carefully polished synthetic diamond which were then treated to make them even tougher and then mounted opposite each other in a device known as a diamond anvil cell.<br />
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"Diamonds are polished with diamond powder, and that can gouge out carbon from the surface," Silvera said. "When we looked at the diamond using atomic force microscopy, we found defects, which could cause it to weaken and break."<br />
The solution, he said, was to use a reactive ion etching process to shave a tiny layer - just five microns thick, or about one-tenth of a human hair - from the diamond's surface. The diamonds were then coated with a thin layer of alumina to prevent the hydrogen from diffusing into their crystal structure and embrittling them.<br />
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After more than four decades of work on metallic hydrogen, and nearly a century after it was first theorized, seeing the material for the first time, Silvera said, was thrilling.<br />
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"It was really exciting," he said. "Ranga was running the experiment, and we thought we might get there, but when he called me and said, 'The sample is shining,' I went running down there, and it was metallic hydrogen.<br />
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"I immediately said we have to make the measurements to confirm it, so we rearranged the lab...and that's what we did," he said. "It's a tremendous achievement, and even if it only exists in this diamond anvil cell at high pressure, it's a very fundamental and transformative discovery."<br />
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<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The findings were published in the <a href="http://science.sciencemag.org/lookup/doi/10.1126/science.aal1579" rel="nofollow" target="_blank">journal Science</a>, provided by <a href="http://www.harvard.edu/" rel="nofollow" target="_blank">Harvard University</a>.</span></u></i></div>

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Exceptionally Preserved Jurassic Sea Life Found in New Fossil Site

Earth History, Fossils 5:12 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-eZCYbS3IxdA/WInmX9TK3FI/AAAAAAAALI4/PJg0A-nhdmgpxMixBp-B1MRM2B2ckZK3gCLcB/s1600/Exceptionally%2Bpreserved%2BJurassic%2Bsea%2Blife%2Bfound%2Bin%2Bnew%2Bfossil%2Bsite.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Exceptionally Preserved Jurassic Sea Life Found in New Fossil Site" border="0" height="384" src="https://1.bp.blogspot.com/-eZCYbS3IxdA/WInmX9TK3FI/AAAAAAAALI4/PJg0A-nhdmgpxMixBp-B1MRM2B2ckZK3gCLcB/s640/Exceptionally%2Bpreserved%2BJurassic%2Bsea%2Blife%2Bfound%2Bin%2Bnew%2Bfossil%2Bsite.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A fossilized mantle of a vampyropod, a relative to the modern vampire squid (pictured on bottom right). The ink sack is the raised structure in the center, and muscles have a striated appearance. Credit: Rowan Martindale/The University of Texas at Austin Jackson School of Geosciences and the Monterey Bay Aquarium Research Institute.</td></tr>
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<i><span style="font-family: "georgia" , "times new roman" , serif;">A trove of exceptionally preserved Jurassic marine fossils discovered in Canada, rare for recording soft-bodied species that normally don't fossilize, is expanding scientists' view of the rich marine life of the period.</span></i><br />
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The preservation of the fossils—which include soft body parts as well as shells and bones—ranks the site among the highest quality sources of Jurassic (183 million year old) marine fossils in the world, and the only such site in North America. A paper describing the site and fossils recovered from it was published online in the journal Geology.<br />
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The presence of fossilized soft tissue is especially significant because it offers a more complete view of life in ancient ecosystems and can help fill the gaps in knowledge connecting extinct organisms to those living today, said Rowan Martindale, a professor at The University of Texas at Austin's Jackson School of Geosciences who led research on the fossils.<br />
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"In a normal fossil deposit, you only preserve a fraction of the organisms that were alive in the past. When you get an extraordinary fossil deposit with soft tissues preserved, you see significantly more of the community that would have been alive," said Martindale, a paleontologist in the Department of Geological Sciences. "Normally, we wouldn't find many of the animals because they lack a skeleton or have a very soft skeleton."<br />
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Collaborators include researchers from Harvard University, Virginia Tech and Florida State University.<br />
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The new site was found on the Parks Canada Ya Ha Tinda Ranch near Banff National Park in southwest Alberta. Co-author Benjamin Gill, a professor at Virginia Tech, spotted the first exceptional fossil when he noticed his Ph.D. student and co-author, Theodore Them, standing right on top of a lobster.<br />
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"The lighting was just right to make out the outline of the lobster," Gill said. "Then we looked around and noticed fossils all around us."<br />
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The lobster was the first sign the site could be special because lobsters' flexible exoskeletons usually aren't preserved as fossils. Other unusual fossils recovered from the site include delicate shrimp, complete fish skeletons with scales and gills, large dolphin-like marine reptiles called ichthyosaurs, as well as "vampyropods" (related to modern vampire squid and octopus) with their delicate ink sacks still intact.<br />
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The presence of many well-preserved, soft-bodied animals marks the new site as a "Konservat-Lagerstätte," a term for fossil beds that preserve an array of organisms with soft tissues as well as hard ones. These sites are rare.<br />
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There are only three other sites, all located in Europe, that are known to contain fossils from the Early Jurassic like the Ya Ha Tinda site. Another famous example of a Canadian Lagerstätte is the Burgess Shale, which preserves a community of soft tissue organisms from the Cambrian Explosion (540 million years ago), named for the burst of animal diversity that appears in the fossil record from this time.<br />
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The new site is about 183 million years old, meaning the fossilized life was alive during the Early Jurassic. At this time, Ya Ha Tinda and the similarly aged European sites were on opposite sides of an ancient continent that became modern-day North America and parts of Europe. Having an array of well-preserved fossils from marine ecosystems on opposite sides of the continent will help scientists understand the distribution of sea life millions of years ago.<br />
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"This is the first time we have a site like this outside of Europe, so the Ya Ha Tinda fossilized community will give us a unique snapshot of life in the Early Jurassic Panthalassa Ocean," Martindale said.<br />
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The researchers have been visiting the site every summer since 2013 and have recovered dozens of fossils, including some that are probably newly discovered species. Notable specimens include a lobster with bulky arms capped with diminutive, scissor-like claws, and 16 new vampyropod specimens, a number that Gill estimates increases known diversity of specimens from North America by threefold.<br />
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"Every time we've gone, we've found something new," Gill said. "It's a really abundant place."<br />
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The next step of the research is to investigate how so many diverse organisms were fossilized together. Researchers think that the high-quality preservation is related to a widespread extinction of marine life caused by a period of extremely low levels of oxygen in parts of the Jurassic oceans. Free of most scavengers, these low oxygen areas could have been an ideal place for a carcass to lay undisturbed and become beautifully fossilized.<br />
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"If a carcass sinks into anoxic water, you're more likely to get the conditions that will favor the preservation of soft tissues, feathers and articulated skeletons," Martindale said. "These 'fossil jackpots' are really special."<br />
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<span style="font-family: "Trebuchet MS", sans-serif;"><i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above post is reprinted from <a href="http://dx.doi.org/10.1130/G38808.1" rel="nofollow" target="_blank">Materials </a>provided by  University of Texas at Austin.</span></u></i></span></div>

Exceptionally Preserved Jurassic Sea Life Found in New Fossil Site

A fossilized mantle of a vampyropod, a relative to the modern vampire squid (pictured on bottom right). The ink sack is the raised struct...

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Fiery eruption of Mexico's Colima volcano sends ash 2 km into air

Video, volcano 3:58 PM

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Mexico's 'fire' volcano has blasted its top again. Dramatic video showed Colima spewing incandescent material early Wednesday morning.<br />
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The explosion was accompanied by a large plume of ash and smoke that rose some 2,000 metres above the crater, with winds carrying the ash towards the northeast, Luis Felipe Puente, head of Mexico's emergency services, said via his Twitter account.<br />
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The volcano is located in western Mexico between the states of Colima and Jalisco and is one of the country's most active. Its eruptions date back to the 16th century, but have been steady since 1994.<br />
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The 3,800-metre volcano has increased in activity since October.<br />
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According to website volcano discovery, increased activity at the volcano is due to the growth of a new lava dome.<br />
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Colima, locally known as the fire volcano, is part of the Pacific Ring of Fire, the 40,000-kilometre volcanically volatile area home to about 75 per cent of the world's active volcanoes.<br />
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Mexico has more than 3,000 volcanoes, but only 14 are considered active.<br />
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The Largest Rough Ruby Crystal in the World

Crystal, Famous Specimens, Gemstones. 2:52 PM

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This unique specimen is one of the world’s largest known rough ruby gemstones. This unique single natural ruby crystal weighs 8.2 lbs. or 18,696 carats. The ruby is semi-translucent to opaque and contains rutile, which may create a six-ray star if cut en cabochon. The crystal displays a strong red fluorescence when exposed to long-wave ultraviolet light. It measures 122.4mm x 112.3mm x 133.9mm.<br />
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<i><span style="font-family: "trebuchet ms" , sans-serif;">The ruby is identified in <a href="http://ruby.125west.com/html/gia_certificate.html" rel="nofollow" target="_blank">GIA Report 15171991</a>.</span></i><br />
<i><span style="font-family: "trebuchet ms" , sans-serif;">Credit<span style="font-family: "trebuchet ms" , sans-serif;">: <a href="http://ruby.125west.com/" rel="nofollow" target="_blank">Ruby</a></span> </span></i></div>

The Largest Rough Ruby Crystal in the World

This unique specimen is one of the world’s largest known rough ruby gemstones. This unique single natural ruby crystal weighs 8.2 lbs. ...

Are we ready for another massive volcanic eruption?

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Understanding New Evidence of the Impact of Climate Change in the Early Jurassic Period

Earth History, Geology 5:49 PM

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<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-FRPWIKFy0bc/WIdpSwOww0I/AAAAAAAALHU/FBbHKFX-4CILHAPKkW9I1dd54tgZHbd9QCLcB/s1600/Understanding%2Bnew%2Bevidence%2Bof%2Bthe%2Bimpact%2Bof%2Bclimate%2Bchange%2Bin%2Bthe%2BEarly%2BJurassic%2BPeriod.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Understanding New Evidence of the Impact of Climate Change in the Early Jurassic Period" border="0" height="277" src="https://4.bp.blogspot.com/-FRPWIKFy0bc/WIdpSwOww0I/AAAAAAAALHU/FBbHKFX-4CILHAPKkW9I1dd54tgZHbd9QCLcB/s400/Understanding%2Bnew%2Bevidence%2Bof%2Bthe%2Bimpact%2Bof%2Bclimate%2Bchange%2Bin%2Bthe%2BEarly%2BJurassic%2BPeriod.jpg" title="" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This shows Early Jurassic ammonite. Credit: Plymouth University</td></tr>
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Geochemical and biological research offers academics a window into earth history, enabling them to piece together events that occurred before records began. Much of our understanding of past climate change is based on geology, in particular the study of sedimentary rocks deposited in the oceans.<br />
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The paper that first recognised and defined Oceanic Anoxic Events (OAEs), written by Oxford professor Hugh Jenkyns and an American colleague, is considered a seminal contribution to geological history, that led the way to numerous studies on the effects of oxygen starvation in the oceans.<br />
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The discovery of organic-rich sediments, often described as black shales, at numerous deep-sea drilling sites during the early 1970s, led to the wider acknowledgement of the oceanic impact of climate change. At certain intervals during the Jurassic era, huge bouts of volcanic activity triggered increased concentrations of atmospheric carbon dioxide. This then caused a knock-on greenhouse effect, raising the sea-surface temperature and reducing oxygen levels in large parts of the ocean.<br />
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At the same, oceans benefited from increased nutrient levels, and as a result marine algae and bacteria bloomed. As they died, these organisms were preserved in sediments that formed on the sea floor and over time changed into source rocks for oil. It is these phenomena that illustrate the causes and effects of OAEs.<br />
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New research, published in Nature Geoscience, has for the first time examined the impact of this type of sediment deposition in lakes. The study demonstrates that lake environments responded in a similar way to climate change, developing the same anoxic conditions as in the oceans.<br />
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Led by Earth Sciences post-graduate student Weimu Xu, the work offers insight into how environmental factors have affected lake formation throughout the ages. Weimu and the  team studied sediments from one of the largest lakes in Earth history – double the size of England and three times the size of Lake Superior – the largest lake (in surface area) in the world today. This ancient lake formed rapidly in the Sichuan Basin, China, as a result of Toarcian (Early Jurassic) climate change, about 183 million years ago.<br />
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Weimu spoke with Science Blog about the study’s key findings and what they can tell us about climate change today.<br />
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The extreme effects of past climatic changes are not limited exclusively to oceans. By dating the lake sediments to the Early Jurassic (Toarcian) period, we were able to show that large lakes formed and were affected in the same way as oceans during an OAE.<br />
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As the climate warmed, the continents experienced increased rainfall, creating lake reservoirs, which essentially acted like mini-oceans. Lake organisms became more abundant, drawing-down massive amounts of carbon dioxide from the atmosphere, which was eventually deposited into sediments. Overtime, these sediments became source rocks for oil.<br />
<h4 style="text-align: left;">
<span style="font-family: Georgia, "Times New Roman", serif;">Lake environments represent their own unique challenges. Did you encounter any specifically?</span></h4>
The biggest challenge for us was establishing the age of the sediments found in the Sichaun Basin, and proving that they were of similar age to those that formed in the oceans during the Toarcian OAE. The wealth of organic matter found in marine environments makes it quite easy to date an event, by basing it on a fossil’s geological age. But lakes do not have such fossils, which makes it much harder to determine the age of the sediments found.<br />
<h4 style="text-align: left;">
<span style="font-family: Georgia, "Times New Roman", serif;">A study of this nature involves a massive amount of work. How did you manage such an extensive undertaking?</span></h4>
Fortunately I worked with a great team. This work was led by myself, co-designed by M. Ruhl, H.C. Jenkyns and S.P. Hesselbo and involved a total of 11 people. The project is a great example of collaborative research.<br />
<br />
We used three distinct methodologies, which would be impossible for any one researcher to master. Colleagues from the University of Durham applied radio-isotopic dating to establish the age of the sediments and colleagues from the British Geological Survey studied the pollen, spores and algae preserved in the sediments. Finally, to give us even more detail to support the age of the sediments, together with colleagues from the University of Bristol and at Shell Global Solutions International B.V., we applied stable carbon-isotope to analyse the sediments, plant and algae remains. These varied techniques convincingly showed that the sediments found, had formed at the same time as the Toarcian OAE.<br />
<br />
We were fortunate to be able to partner with experts in these three fields, and of course our industrial partner Shell.<br />
<h4 style="text-align: left;">
<span style="font-family: Georgia, "Times New Roman", serif;">How long did the research take to conduct?</span></h4>
The study lasted from the first sampling trip in November 2013 to completion of this manuscript in September 2016. We also had to factor in time to get permission to publish the findings, from the oil companies providing the data.<br />
<h4 style="text-align: left;">
<span style="font-family: Georgia, "Times New Roman", serif;">Are there any long-term impacts associated with your findings?</span></h4>
There are definite links between the climatic event identified in the Toarcian and present-day global warming. A better understanding of past climate systems could help predict environmental and ecological changes in a future greenhouse world. While the lake we studied existed in the Early Jurassic period, there are lakes today in African and British Columbia for example, that have been affected by global warming. They are becoming more and more anoxic and some are losing fishery stocks as a result. People fixate on warmth, but anoxia goes hand in hand with warmth.<br />
<br />
There’s a certain irony in the fact that the conditions which created oil and gas deposits millions of years ago are being recreated much more rapidly by burning of these fossil fuels.<br />
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">How would you like to see this work used in the future?</span></h4>
Our study directly links lake formation and sediment deposition to the Toarcian OAE. By studying other lake sediments that were around at that time, researchers could establish if they also link to this event. For a better understanding of major climatic change in other intervals of the Earth’s history, people can also look and see if there were other major lake reservoirs that acted similarly.<br />
<br />
It would also be useful to understand the impact, not only of carbon deposition, but carbon burial, during times of major climatic change, and how that impacted coal formation. This is something I am very keen to focus on next.<br />
<br />
<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above post is reprinted from <a href="http://www.ox.ac.uk/news/science-blog/lakes-well-oceans-understanding-new-evidence-impact-climate-change-early-jurassic" rel="nofollow" target="_blank">materials</a> provided by <a href="http://www.ox.ac.uk/" rel="nofollow" target="_blank">University of Oxford</a>.</span></i></u><span style="box-sizing: border-box; color: black; font-family: "verdana" , "geneva" , sans-serif; font-size: 14px; font-style: normal; font-weight: normal; letter-spacing: normal; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><br style="box-sizing: border-box;" /></span></div>

Understanding New Evidence of the Impact of Climate Change in the Early Jurassic Period

This shows Early Jurassic ammonite. Credit: Plymouth University Geochemical and biological research offers academics a window into ear...

Meteorite Identification: Identify Meteorites in 7 Steps

Meteorite, Mineralogy 3:25 PM

<div style="text-align: left;" trbidi="on"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJTVfhMpfIuh_5JV7Uw0JW7IhkpTpcozEdUpomje4wj5l_si_gKgHSh4tabvYHeuNNVk8YLo7_mgpGaW-yucq1RE3oJfwESnioV0n5_SoPumertPoACC7VrdhCrTSGWFipCuA6z-vC19mVvuuQJEzWDhn5lxd20F1roNRMZDyvuRjHxnPv6h86Jr-b/s1421/Meteorite%20Identification%20Identify%20Meteorites%20in%207%20Steps.jpeg" style="margin-left: auto; margin-right: auto;"><img alt="Meteorite Identification: Identify Meteorites in 7 Steps" border="0" data-original-height="947" data-original-width="1421" height="426" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJTVfhMpfIuh_5JV7Uw0JW7IhkpTpcozEdUpomje4wj5l_si_gKgHSh4tabvYHeuNNVk8YLo7_mgpGaW-yucq1RE3oJfwESnioV0n5_SoPumertPoACC7VrdhCrTSGWFipCuA6z-vC19mVvuuQJEzWDhn5lxd20F1roNRMZDyvuRjHxnPv6h86Jr-b/w640-h426/Meteorite%20Identification%20Identify%20Meteorites%20in%207%20Steps.jpeg" title="Meteorite Identification: Identify Meteorites in 7 Steps" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Meteorite Identification: Identify Meteorites in 7 Steps. Photo: © Vladimir / Adobe Stock <br /></td></tr></tbody></table>
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</div><h3 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Have an interesting rock in your possession and want to see if it’s out of this world? </span></h3>
A <b>meteorite </b>is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the Earth's atmosphere and impact with the Earth's surface or that of another planet.<br />
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When the object enters the atmosphere, various factors like friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate that energy. It then becomes a meteor and forms a fireball, also known as a shooting star or falling star; astronomers call the brightest examples "bolides." Meteorites that survive atmospheric entry and impact vary greatly in size. For geologists, a bolide is a meteorite large enough to create a crater.<br />
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Most meteoroids disintegrate when entering the Earth's atmosphere. Usually, five to ten a year are observed to fall and are subsequently recovered and made known to scientists. Few meteorites are large enough to create large impact craters. Instead, they typically arrive at the surface at their terminal velocity and, at most, create a small pit.<br />
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<a href="https://3.bp.blogspot.com/-cSypxJKkgAA/WIc_I8nsMRI/AAAAAAAALHE/aIjDbxt5vDAZvJP0csUhh-It-mqJi4SOACLcB/s1600/Chart%2Bshowing%2Btypes%2Bof%2Basteroids%2Band%2Bmeteorites.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="How to Identify Meteorites in 7 Steps" border="0" height="486" src="https://3.bp.blogspot.com/-cSypxJKkgAA/WIc_I8nsMRI/AAAAAAAALHE/aIjDbxt5vDAZvJP0csUhh-It-mqJi4SOACLcB/w640-h486/Chart%2Bshowing%2Btypes%2Bof%2Basteroids%2Band%2Bmeteorites.jpg" title="Meteorite Identification: Identify Meteorites in 7 Steps" width="640" /></a></div>
<h3 style="text-align: left;">
<b><span style="font-family: "georgia" , "times new roman" , serif;"><br /></span></b></h3><br /><h4><span style="color: #2b00fe;"> Below you will find descriptions of seven different tests you can do to determine if the rock in question is a meteorite.</span></h4><b><span style="font-family: "georgia" , "times new roman" , serif;">1. Metal</span></b><br />
Most meteorites contain at least some metal. Do you see the metal shining on a broken surface? If so, you might have a meteorite.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">2. Density</span></b><br />
Density - Those meteorites that do have a lot of metal tend to be very dense compared to regular rocks. Do you have something very dense such that it could be a meteorite? But remember that not all meteorites are dense.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">3. Magnetic Properties</span></b><br />
Magnetic Properties - A lot of meteorites contain shiny iron-nickel metal grains or consist largely of iron-nickel metal. The iron in the metal attracts a magnet. Is a magnet attracted to the surface of your sample? If so, you might have a meteorite. But remember that a lot of normal rocks on the Earth are also magnetic. So, just because something is magnetic, it doesn't mean that it is a meteorite.<br /><br /></div><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://3.bp.blogspot.com/-e7oCjhv0p8s/WdEmt2uB2mI/AAAAAAAANjg/cbZtTL7kOn4ng_ZkkhizX1f9e44aoGAPwCLcBGAs/s1600/This%2Bsmall%2Bmeteorite%2Bis%2Bfrom%2Bthe%2BNWA%2B869%2Bstrewn%2Bfield%252C%2Bnear%2BTindouf%252C%2BAlgeria..jpg" style="margin-left: auto; margin-right: auto;"><img alt="How to Identify Meteorites in 7 Steps" border="0" data-original-height="768" data-original-width="1024" height="300" src="https://3.bp.blogspot.com/-e7oCjhv0p8s/WdEmt2uB2mI/AAAAAAAANjg/cbZtTL7kOn4ng_ZkkhizX1f9e44aoGAPwCLcBGAs/w400-h300/This%2Bsmall%2Bmeteorite%2Bis%2Bfrom%2Bthe%2BNWA%2B869%2Bstrewn%2Bfield%252C%2Bnear%2BTindouf%252C%2BAlgeria..jpg" title="Meteorite Identification: Identify Meteorites in 7 Steps" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This meteorite is from 
the NWA 869 strewn field, near Tindouf, Algeria. </td></tr>
</tbody></table><br />
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<span style="font-family: "georgia" , "times new roman" , serif;"><b>4. Chondrules </b></span><br />
Some primitive meteorites have little round pieces of stony material in them. These little round pieces are called chondrules. Some sedimentary and volcanic rocks can have spherical particles that look somewhat like chondrules. Does your sample contain chondrules? If it does, you might have a meteorite.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">5. Fusion crust </span></b><br />
When a meteorite is falling through the atmosphere, it begins to heat up because of the extreme compression of the atmosphere. The meteor gets so hot that the outer surface begins to melt, which produces a thin black/brown coating on the surface of the rock called a fusion crust. Iron meteorites may show evidence of melted metal on their surface, but this is less common. Fusion crusts are present on freshly fallen meteorites, but the crusts are fragile and can weather away from samples that fell a long time ago. Small patches of fusion crust can sometimes remain in hollows of the sample. Does your sample have a fusion crust? If so, you have a meteorite.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">6. Regmaglypt texture/thumbprints</span></b><br />
When the surface of the meteorite begins to melt during entry into the atmosphere, some areas of the meteorites are eroded by the melting more than others, almost like someone is taking little scoops of material out. This leaves a bunch of small dents in the surface of the rock, making it look like someone put thumbprints into clay. The surface of most meteorite samples have these thumbprints called “regmaglypts,” which can vary in size from less than a centimeter up to as much as 10 centimeters. Does your sample have Regmaglypt texture/thumbprints? If so, you have a meteorite.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">7. Streak</span></b><br />
Most meteorites won’t leave a streak, but the surfaces of some meteorites might leave a reddish streak if they have been oxidized (rusted). If you drag your sample across this “streak plate,” and it leaves a red/orange line, then the sample is probably a common mineral on the Earth called hematite. If the sample is magnetic and leaves a black or gray streak, then it might be the common terrestrial iron-oxide mineral called magnetite. Does your sample cause a streak on a “streak plate?” If not, you may have a meteorite.<br />
<br />
<div class="pw-hidden-cp">
<a href="http://www.geologyin.com/2017/06/the-meteorite-largest-ever-found-in.html" target="_blank">The Largest Meteorite Ever Found in the United States </a></div>
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<u><i><span face=""trebuchet ms" , sans-serif"><br /></span></i></u></div>
<div class="pw-hidden-cp">
<u><i><span face=""trebuchet ms" , sans-serif">The above story is based on Materials provided by <a href="http://www.dawn-mission.org/Meteorite/index.asp" rel="nofollow" target="_blank">NASA’s Dawn Mission</a>.</span></i></u></div>
</div>

Meteorite Identification: Identify Meteorites in 7 Steps

Meteorite Identification: Identify Meteorites in 7 Steps. Photo: © Vladimir / Adobe Stock Have an interesting rock in your possession and...

Tsunami Warning for Us West Coast After Magnitude-7.9 Earthquake Off Alaska

News 3:44 PM

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<span style="font-family: "georgia" , "times new roman" , serif;">A magnitude-7.9 earthquake detected in the Gulf of Alaska has triggered tsunami warnings in Alaska and tsunami watches across several Western states.</span><br />
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<b><span style="color: red;">Update:</span></b><br />
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<span style="background-color: #cfe2f3;"><span style="font-family: "georgia" , "times new roman" , serif;"><b>A tsunami watch has also been cancelled for British Columbia, Canada.  <br /> The watch was cancelled earlier for the US states of Washington, Oregon and California.  <br /> The advisory remains in place for southern Alaska, according to reports.</b></span></span><br />
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</blockquote>
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A tsunami warning is in effect for southeast and south Alaska, including the Alaska Peninsula and Aleutian Islands, as well as British Columbia in Canada. A tsunami watch is in effect for California, Oregon and Washington, according to the Tsunami Warning Center.<br />
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As of 2:29 a.m. (6:29 a.m. ET), water in the harbor near Kodiak was receding, the city's police department tweeted, after earlier urging residents to get at least 100 feet above sea level.<br />
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"Citizens should remain in place and wait for further updates," Kodiak police said.<br />
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Receding water can be a dangerous precursor to a significant tsunami, CNN meteorologist Dave Hennen said.<br />
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"Think of a sloshing bathtub with a water level dropping, only to rise extremely quickly," he said. "The tsunami would come in waves. In some occasions, the first wave is not the largest."<br />
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The San Francisco Department of Emergency Management warned residents within three blocks of the Pacific Coast or within five blocks of the San Francisco Bay to prepare to evacuate, "so that you are ready if evacuation is needed," the agency tweeted.<br />
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The earthquake struck about 175 miles southeast of Kodiak, Alaska, shortly after midnight Alaska local time, according to preliminary figures from the United States Geological Survey. The quake had a depth of about 15 miles, according to the USGS. Previously, the earthquake had been measured at magnitude 8.2.</div>

Tsunami Warning for Us West Coast After Magnitude-7.9 Earthquake Off Alaska

A magnitude-7.9 earthquake detected in the Gulf of Alaska has triggered tsunami warnings in Alaska and tsunami watches across several...

Aventurescence: Light-Reflecting Inclusions That Produce a Bright Flash

Gemstones., Mineralogy 3:28 PM

Aventurescence: Light-Reflecting Inclusions That Produce a Bright Flash

Sunstone from Oregon Aventurescence is an optical reflectance effect seen in certain gems. The effect amounts to a metallic glitter...

Conditions Right for Complex Life Come and Go?

Earth History, Geology 4:28 PM

Conditions Right for Complex Life Come and Go?

This is a 1.9-billion-year-old stromatolite -- or mound made by microbes that lived in shallow water -- called the Gunflint Formation in ...

Geology In