10 Most Incredible Plunge Waterfalls on Earth Plunge waterfalls are waterfalls that drop vertically while losing contact with the underlying cliff face, or bedrock, behind them.
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Tranquillityite [Fe2+8(ZrY)2Ti3Si3O24] was first discovered in mare basalts collected during the Apollo 11 lunar mission to the Sea of Tranquillity. The mineral has since been found exclusively in returned lunar samples and lunar meteorites, with no terrestrial counterpart. We have now identified tranquillityite in six dolerite dikes and sills from Western Australia. Terrestrial tranquillityite commonly occurs as clusters of fox-red laths closely associated with baddeleyite and zirconolite in quartz and K-feldspar intergrowths in late-stage interstices between plagioclase and pyroxene. Its composition is relatively uniform, comprising mostly Si, Zr, Ti, and Fe, with minor Al, Mg, Mn, Ca, Nb, Hf, Y, and rare earth elements. Its habit and chemistry are consistent with tranquillityite in lunar basalts, and it has a face-centered-cubic subcell, similar to that of annealed lunar tranquillityite. Unlike coexisting baddeleyite and zirconolite, it is commonly altered to a secondary intergrowth of submicron phases comprising mainly Si, Ti, and Ca, with minor Zr. In situ sensitive high-resolution ion microprobe (SHRIMP) U-Pb geochronology of tranquillityite from sills intruding the Eel Creek Formation, northeastern Pilbara Craton, yields a 207Pb/206Pb age of 1064 ± 14 Ma. This age indicates that the previously undated sills belong to the ca. 1070 Ma Warakurna large igneous province, extending the geographic range of this mafic complex. The date also provides a new minimum age (>1.05 Ga) for the intruded sedimentary rocks, which were previously thought to be Neoproterozoic. Examination of dolerite from Western Australia suggests that tranquillityite is a relatively widespread, albeit volumetrically minor, accessory mineral and, where sufficiently coarse, it represents an exceptional new U-Pb geochronometer.
Received 2 June 2011.Revision received 25 August 2011.Accepted 30 August 2011.© 2012 Geological Society of America
The cave huge crystals opened in 2000 at a depth of 300 meters drilling shafts in the Mexican town of Nike’s Chihuahua state. The main room contains a large crystals of selenite (a form of gypsum), some of which are the largest natural crystals ever found on earth. In cave is huge crystals is very hot: the temperature reaches 58 ° C with 90-99% humidity. Therefore this cave not fully explored, because without serious protection here can be no more than 10 minutes.
Stony meteorites, the most common type of meteorite, are generally composed of approximately 75 to 90 percent silicon-based minerals, 10 to 25 percent nickel-iron alloy, and trace amounts of iron sulfide. Stony meteorites account for 94 percent of observed meteorite falls.
Warden; an ordinary (H5) chondrite from Western Australia. Photo © D. Ball, ASU
Chondrites, the most abundant type of stony meteorite, contain some of the first objects to have formed in the solar system, such as calcium-aluminum-rich particles and chondrules (from which chondrites get their name), and have never undergone melting. Their chemistry is very primitive because they have had very few chemical interactions with other objects since their formation. Chondrites are the most common meteorites found on Earth, accounting for approximately 86 percent of all meteorites recovered.
Mezö-Madaras, Romania, ordinary chondrite. This cut and polished face measures about 7 centimeters across. Chondrites are named for the nearly spherical, silicate rich particles called chondrules, which are clearly visible in this close-up and were among the first objects to have formed in our solar system. Photo by D. Ball, ASU.
Achondrites originate on differentiated planetary bodies, such as asteroids, Planets, or moons, and were reformed from molten fragments that were flung into space as the result of another collision. Because achondrites closely resemble terrestrial rocks to the naked eye, they are less commmonly encountered as finds. Most achondrites in the Center's collection were observed falls.
Johnstown, CO, diogenite. Diogenite achondrites are primarily composed of orthopyroxene, a silicate mineral. The Johnstown meteorite is brecciated—composed of many sharp fragments that were naturally cemented together—and contains large grains of orthopyroxene held together by crushed and broken orthopyroxene. This specimen is about 13 centimeters long. Photo by D. Ball, ASU.
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Most iron meteorites likely originate in the cores of large asteroids, and are composed almost entirely of nickel-iron alloy, which is also a primary component of the Earth's core. Even though they account for only five percent of observed falls, they are more easily recognized than other types of meteorites.
Rancho Gomelia, Mexico, octahedrite. This iron meteorite has been cut, polished, and etched with acid on one face to reveal an interlocking crystal structure of nickel-iron alloys of varying composition. Photo by D. Ball, ASU.
Stony-iron meteorites contain approximately even amounts of silicates and nickel-iron alloy.
Pallasites are believed to form in between the silicate mantle, or outer shell, and molten metal core of an asteroid. The primary silicate mineral in pallasites is olivine, distinguishable by its greenish hue.
Albin, WY, pallasite. This slice, which is about 18 centimeters long, has been illuminated from behind to distinguish its olivine content from the surrounding metal. Photo by D. Ball, ASU.
Mesosiderites are likely formed by collisions of metal-rich and silicate-rich asteroids.
Hainholz, Germany, mesosiderite. This cut and polished face, which is about 9 centimeters across, reveals the complex mixture of metal and pyroxene, a silicate mineral, that is typical of mesosiderites. Photo by D. Ball, ASU.
Corundum is frequently used as an abrasive and is world famous as the mineral of rubies and sapphires
A team of scientists observed magnesium oxide in extreme pressures and temperatures to understand what is happening deep within the Earth's layer and found some surprising results.
The mantle is divided into sections:
Magnesium oxide is particularly resistant to changes when under intense pressures and temperatures. Theoretical predictions claim that it has just three unique states with different structures and properties present under planetary conditions: solid under ambient conditions (such as on the Earth's surface), liquid at high temperatures, and another structure of the solid at high pressure. The latter structure has never been observed in nature or in experiments.
McWilliams and his team observed magnesium oxide between pressures of about 3 million times normal atmospheric pressure (0.3 terapascals) to 14 million times atmospheric pressure (1.4 terapascals) and at temperatures reaching as high as 90,000 degrees Fahrenheit (50,000 Kelvin), conditions that range from those at the center of our Earth to those of large exo-planet super-Earths. Their observations indicate substantial changes in molecular bonding as the magnesium oxide responds to these various conditions, including a transformation to a new high-pressure solid phase.
In fact, when melting, there are signs that magnesium oxide changes from an electrically insulating material like quartz (meaning that electrons do not flow easily) to a metal similar to iron (meaning that electrons do flow easily through the material).
Drawing from these and other recent observations, the team concluded that while magnesium oxide is solid and non-conductive under conditions found on Earth in the present day, the early Earth's magma ocean might have been able to generate a magnetic field. Likewise, the metallic, liquid phase of magnesium oxide can exist today in the deep mantles of super-Earth planets, as can the newly observed solid phase.
"Our findings blur the line between traditional definitions of mantle and core material and provide a path for understanding how young or hot planets can generate and sustain magnetic fields," McWilliams said.
"This pioneering study takes advantage of new laser techniques to explore the nature of the materials that comprise the wide array of planets being discovered outside of our Solar System," said Russell Hemley, director of Carnegie's Geophysical Laboratory. "These methods allow investigations of the behavior of these materials at pressures and temperatures never before explored experimentally."
Javier Trueba/MSF/Photo Researchers Inc.
First discovered about a decade ago, the largest known cave crystals—single hunks of gypsum as much as 11 meters long, 1 meter thick, and weighing 55 tons—could have taken up to 1 million years to grow, a new study suggests. The cavern in the Mexican silver and lead mine where the crystals were found was filled with mineral-rich waters until 1975, when it was drained to provide miners with access to new ore veins. Lab tests indicate that the gypsum hunks crystallized at temperatures between 54°C and 58°C, researchers report online today in the Proceedings of the National Academy of Sciences. By immersing a hunk of gypsum in a sample of the cave's waters and using a microscopic imaging technique that allowed the scientists to directly measure crystal growth, the team found that at 55°C, near the temperature at which the crystals would have grown most slowly, it would take around 990,000 years for a gypsum crystal 1 meter in diameter to form. At water temperatures of 56°C, the same crystal could have formed in about 500,000 years.
One of the things that I realised whilst at EGU last week was how broad the subject of geology actually is and how we don’t always appreciate the breadth of our subject. Some of this obviously come from the influence of interdisciplinary studies like my own, but some it comes from the unique and innovative ways that geoscientists are attempting to broaden our understanding of the planet. To highlight this I have picked out 5 things you wouldn’t expect to see at a geology conference –
1- Astronaut photographs
Recently, the work of astronaut Commander Hadfield brought the activities of the people who get strapped to a rocket and propelled beyond our atmosphere to learn more about our planet back into the public eye. But although the images they produce are beautiful, inspiring and humbling all at the same time, they are often not very useful because there is no way for scientists to tell the scale of the image or where exactly it was taken. The work of Reichart, Walsh and Taylor addresses this problem by using ‘starfield recognition software‘ to calculate the height and location of the images. Now I don’t know about you, but there is something so romantic sounding about starfield recognition software. It makes me think that the software we so often associate with catching criminals can actually be used for something uplifting and will, once fully developed, improve our understanding of how the Auroras (both Australis and Borealis) work.
2- Willow tree root growth patterns
When you think of geology, willow is probably not the first thing that springs to mind. However, when you think about landslides – which are most definitely geological – the presence, absence or behaviour of plants is very important. In Central Asia (amongst other places) willow is vital in facilitating the colonisation of other tree species in forests that help protect the soil from erosion. This study, although it seems like it belongs in a botany (or at least biology) conference is actually examining the material necessary to mitigate the effects of erosion, which can lead to lots of other geological problems.
3- Fluid dynamics of cars
This had to be one of my favourite posters – mostly due to the obvious/unexpected dichotomy of the contents. If you picture a flood, what do you see? Rushing muddy brown water tearing away at the countryside, carrying the odd tree? Perhaps. But more and more often nowadays floods are affecting our urban areas, and the thing the floodwater is likely to be dragging is a car not a tree. This work by Arrighi, Castelli and Oumeraci takes a closer look at how vehicles are affected by flood water and how they affect the flow themselves. It’s also a sobering look at how easy it is to loose control of a vehicle in a flood and explains why most studies identify the greatest cause of deaths from drowning in a flood to be a car.
4- Coffee residue
If the conference last week was attended by over 12,000 delegates, how many cups of coffee were drunk do you think (added to the fact that it was nigh on impossible to get a good cup of tea)? Now imagine you could take the dregs of all that coffee and do something useful with it! Well that is precisely what Fotopoulou, Karapanagioti and Manariotis were exploring- how to use coffee residues to make biochar. Biochar is a carbon-rich substance that is added to soils in order to sequester carbon, improve the quality (fertility) of the soil and assist in environmental remediation. Who knew an old cup of coffee could be so useful?!
5- Wind patterns in the Pacific
So wind may not be that disconnected from geology – but wind patterns? Over water? Yes at a geology conference a geoscientist’s awareness of the processes that shape our planet extends even to the climate. Which is not all that surprising really when you consider that one of the biggest issues and areas of study that geologists deal with nowadays is climate change.
These are only the posters that I came across and thought interesting during the conference –I’m sure there were many many more! Did you see any examples of a poster or a presentation that you wouldn’t expect to see at a geology conference?!
Photo in the news: A volcano in Indonesia erupts 220 times in one week, spraying hot ash and poisonous gas on local villages.
Mount Sinabung—a volcano in Indonesia—has erupted 220 times in the past week and displaced more than 20,000 local villagers.
The 8,530-foot-high (2,600-meter-high) volcano has been erupting since September 2013. Even though the volcano has been active for several months, local authorities have confirmed that the eruptions are intensifying.
On Sunday, Mount Singabung released a plume of hot ash measuring 4,000 meters high.
The Indonesian government has evacuated residents living near the volcano, displacing more than 20,000 villagers living within the danger zone, currently defined as a radius of 5 kilometers (3.1 miles) around the volcano's peak.
It has recently been extended to 7 kilometers (4 miles) southeast of the volcano where, according to the Wall Street Journal, volcanic activity is reported to be much higher.
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Yellowstone supervolcano 'even more colossal'
by Rebecca Morelle posted on December 14, 2013 07:50PM GMT
Thanks to Alan4discussion for the link!
The supervolcano that lies beneath Yellowstone National Park in the US is far larger than was previously thought, scientists report.
A study shows that the magma chamber is about 2.5 times bigger than earlier estimates suggested.
Yellowstone hot spring Hot springs are surface evidence of the huge magma chamber that sits beneath Yellowstone
A team found the cavern stretches for more than 90km (55 miles) and contains 200-600 cubic km of molten rock.
The findings are being presented at the American Geophysical Union Fall Meeting in San Francisco.
Prof Bob Smith, from the University of Utah, said: “We’ve been working there for a long time, and we’ve always thought it would be bigger... but this finding is astounding."
If the Yellowstone supervolcano were to blow today, the consequences would be catastrophic.
The last major eruption, which occurred 640,000 years ago, sent ash across the whole of North America, affecting the Planet’s climate.
This been a particularly eventful year for the world's volcanoes. Out of an estimated 1,500 active volcanoes, 50 or so erupt every year, spewing steam, ash, toxic gases, and lava. In 2013, erupting volcanoes included Italy's Mount Etna, Alaska's Mount Pavlof, Indonesia's Mount Sinabung, Argentina's Volcán Copahue, and a new island emerging off the coast of Nishinoshima, Japan. In Hawaii, the famed Kilauea volcano continued to send lava flowing toward the sea. Collected below are scenes from the wide variety of volcanic activity on Earth over the past year. [36 photos]
"We found that the hematite from this core was made of a single crystal and therefore was not hematite made by ultra violet radiation," said Ohmoto.
This could only happen if the deep ocean contained oxygen and the iron rich fluids came into contact at high temperatures. Ohmoto and his team believe that this specific layer of hematite formed when a plume of heated water, like those found today at hydrothermal vents, converted the iron compounds into hematite using oxygen dissolved in the deep ocean water.
"This explains why this hematite is only found in areas with active submarine volcanism," said Ohmoto. "It also means that there was oxygen in the atmosphere 3.46 billion years ago, because the only mechanism for oxygen to exist in the deep oceans is for there to be oxygen in the atmosphere."
In fact, the researchers suggest that to have sufficient oxygen at depth, there had to be as much oxygen in the atmosphere 3.46 billion years ago as there is in today's atmosphere. To have this amount of oxygen, the Earth must have had oxygen producing organisms like cyanobacteria actively producing it, placing these organisms much earlier in Earth's history than previously thought.
"Usually, we look at the remnant of what we think is biological activity to understand the Earth's biology," said Ohmoto. "Our approach is unique because we look at the mineral ferric oxide to decipher biological activity."
Ohmoto suggests that this approach eliminates the problems trying to decide if carbon residues found in sediments were biologically created or simply chemical artifacts.
Note: This story has been adapted from a news release issued by the Penn State.
"The nanodiamonds that we found at all six locations exist only in sediments associated with the Younger Dryas Boundary layers, not above it or below it," said Kennett, a UO archaeologist. "These discoveries provide strong evidence for a cosmic impact event at approximately 12,900 years ago that would have had enormous environmental consequences for plants, animals and humans across North America."
Note: This story has been adapted from a news release issued by the University of Oregon.
In honor of Echinoderm Week for my Invertebrate Paleontology course, we have a beautiful crinoid calyx (or crown, or just “head”) on a slab from the Burlington Limestone (Lower Carboniferous, Osagean) found near Burlington, Iowa.
Number of Earthquakes Worldwide for 2000 - 2012
Located by the US Geological Survey National Earthquake Information Center
(M4.5+ for most of the world; doesn't include US regional network contributions)