August 2014

Amazing Labradorite

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<b style="background-color: white; color: #252525; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">Labradorite</b><span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"><span style="color: #252525;"> </span>((</span><span style="color: black;">Ca<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">, </span>Na<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">)(</span>Al<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">, </span>Si<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">)</span><sub style="background-color: white; font-family: sans-serif; line-height: 1;">4</sub>O<sub style="background-color: white; font-family: sans-serif; line-height: 1;">8</sub><span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">), a </span>feldspar<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> </span>mineral<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">, is an intermediate to calcic member of the </span>plagioclase<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> series. It is usually defined as having "%An" (</span>anorthite<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">) between 50 and 70. The </span>specific gravity<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> ranges from 2.68 to 2.72. The streak is white, like most</span>silicates<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">. The </span>refractive index<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> ranges from 1.559 to 1.573. </span>Twinning<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> is common. As with all plagioclase members, the crystal system is</span>triclinic<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">, and three directions of </span>cleavage<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> are present, two of which form nearly right angle prisms. It occurs as clear, white to gray, blocky to lath shaped grains in common </span>mafic<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> </span>igneous rocks<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> such as </span>basalt<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> and </span>gabbro<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">, as well as in </span>anorthosites<span style="background-color: white; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">.</span></span><br />
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Amazing Labradorite

Labradorite (( Ca , Na )( Al , Si ) 4 O 8 ), a feldspar mineral , is an intermediate to calcic member of the plagioclase series...

The Earthquake in Kobe

Tectonic 9:54 PM

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 1995 Great Hanshin Earthquake (M=6.9), commonly referred to as the Kobe earthquake,  Collapsed Hanshin Expresswaywas one of the most devastating earthquakes ever to hit Japan; more than 5,500 were killed and over 26,000 injured.<br />
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The economic loss has been estimated at about $US 200 billion. The proximity of the epicenter, and the propagation of rupture directly beneath the highly populated region, help explain the great loss of life and the high level of destruction. (On line report of Kobe earthquake).<br />
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The spectacular collapse of the Hanshin expressway illustrates the effects of the high (above, KG)  Nishinomiya Bridge loads that were imposed on structures in the area. The strong ground motions that led to collapse of the Hanshin Express way also caused severe liquefaction damage to port and wharf facilities as can be seen to the left and below (GH).<br />
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The Earthquake in Kobe

1995 Great Hanshin Earthquake (M=6.9), commonly referred to as the Kobe earthquake, Collapsed Hanshin Expresswaywas one of the most...

Folding of the Rocks at Lulworth Cove

folds, Structural Geology 8:35 PM

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<span style="font-family: inherit;">When the continents of Africa and Europe collided 24-1.5 million years ago the effects were far reaching causing changes in the rock formations many hundreds of miles away. The rocks at Lulworth were lifted, twisted and folded over 90 into their present position. </span><br />
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<span style="font-family: inherit;">The collision of theearth's tectonic plates left visible waves in the rock where faults or weaknesses in the rock strata responded to the pressure causing the folding that can be seen. </span><br />
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Folding of the Rocks at Lulworth Cove

When the continents of Africa and Europe collided 24-1.5 million years ago the effects were far reaching causing changes in the rock for...

Geologists Find Source of Stonehenge’s Inner Stones

Geology 2:16 PM

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By Mark Brown, Wired UK<br />
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A team of geologists from Britain have pinpointed the exact quarry that Stonehenge’s innermost circle of rocks came from. It’s the first time that a precise source has been found for any of the stones at the prehistoric monument.<br />
Robert Ixer of the University of Leicester and Richard Bevins of the National Museum of Wales painstakingly identified samples from various rock outcrops in Pembrokeshire, Wales.<br />
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For nine months the pair used petrography — the study of mineral content and textural relationships within rocks — to find the origins of Stonehenge‘s rhyolite debitage stones. These spotted dolerites or bluestones form the inner circle and inner horseshoe of the site.<br />
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They found the culprit on a 65-metre-long outcropping called Craig Rhos-y-Felin, near Pont Saeson in north Pembrokeshire. It lies approximately 160 miles from the Stonehenge site.<br />
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The question remains though, as to how neolithic people transported huge chunks of rock from Wales to Wiltshire, some 5,000 years ago. Some historians reckon that these stone age builders quarried the stones in Pembrokeshire and brought them over to England, while others argue that giant glacial shifts moved the stones, hundreds of thousands of years earlier.<br />
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Ixer and Bevins hope that by finding the exact source for some of the monument’s stones, they will be able to discover new clues as to when and how they made their 160 mile journey.<br />
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The more well-known and iconic stones, the huge sarsens, were incorporated into the monument several centuries later. They came from somewhere in the Marlborough Downs, 20 miles north of Stonehenge.</div>
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Geologists Find Source of Stonehenge’s Inner Stones

By Mark Brown, Wired UK A team of geologists from Britain have pinpointed the exact quarry that Stonehenge’s innermost circle of rock...

The 100-Million-Year-Old Spider Attack Captured in Amber

Amber Fossils, Earth History, Fossils 7:53 PM

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<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Image: Oregon Sate University</span></td></tr>
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<span style="font-size: small;"><a href="http://2.bp.blogspot.com/-QRht5z7VVUw/U_UN5L8v_VI/AAAAAAAABgs/pRZxSJ5V-5M/s1600/spider.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><br />
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<span style="font-family: inherit; font-size: small;"><span style="font-family: "georgia" , "times new roman" , serif;">Looks like this 100-million-year old spider didn’t get to enjoy its final meal.</span></span></h3>
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Trapped in a piece of amber, the juvenile spider appears to be on the cusp of devouring a male wasp that was caught in its web. Such a grisly scene between spider and prey has never before been found in the fossil record.<br />
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The amazing snapshot shows an event that occurred in the Early Cretaceous period, about 97 to 110 million years ago, in the Hukawng Valley of Myanmar, “almost certainly with dinosaurs wandering nearby,” as the press release about this discovery reports. <br />
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<span style="font-family: inherit; font-size: small;">The spider is a social orb-weaver spider, formally known as Geratonephila burmanica, and its victim is a wasp of the species Cascoscelio incassus. Both species are extinct today but the fossil suggests that insect behavior from the past is not too different from the present.<br />
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Related wasp species are known to parasitize spider eggs, so there is some poetic justice in the spider’s attack. “This was the wasp’s worst nightmare, and it never ended. The wasp was watching the spider just as it was about to be attacked, when tree resin flowed over and captured both of them,” said entomologist George Poinar Jr. of Oregon State University in the release.<br />
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This latest fossil doesn’t just capture the dramatic spider attack but also evidence of spider social life in the Early Cretaceous. Another spider, an adult male, is captured some distance away in the amber, co-habiting on the same web as the juvenile. Males of modern-day social orb-weavers are typically found living on female-constructed webs, where they assist in capturing insects and maintaining the web.<br />
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</span><span style="font-size: small;"><i><u><span style="font-family: "trebuchet ms" , sans-serif;">The study was published  in the journal <a href="http://www.tandfonline.com/toc/ghbi20/current" rel="nofollow" target="_blank"><i>Historical Biology</i></a>.</span></u></i></span></div>

The 100-Million-Year-Old Spider Attack Captured in Amber

Image: Oregon Sate University Looks like this 100-million-year old spider didn’t get to enjoy its final meal. Trapped in a pie...

Oldest Preserved Spider Web Dates Back to Dinosaurs

Amber Fossils, Earth History, Fossils 10:49 PM

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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-HgrlUBSplfs/W-rx1TZp2YI/AAAAAAAAQj0/Z5Y7yO2_J1kCkRUVEfawe0_1gE37SppcwCLcBGAs/s1600/Oldest%2BPreserved%2BSpider%2BWeb%2BDates%2BBack%2Bto%2BDinosaurs%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Oldest Preserved Spider Web Dates Back to Dinosaurs" border="0" data-original-height="783" data-original-width="1200" height="416" src="https://3.bp.blogspot.com/-HgrlUBSplfs/W-rx1TZp2YI/AAAAAAAAQj0/Z5Y7yO2_J1kCkRUVEfawe0_1gE37SppcwCLcBGAs/s640/Oldest%2BPreserved%2BSpider%2BWeb%2BDates%2BBack%2Bto%2BDinosaurs%2B%25281%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"> Baltic amber. Photo: Brocken Inaglory</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;"> The world’s oldest known spider web has been discovered on a beach in Sussex, England, trapped inside an ancient chunk of amber.</span><br />
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Scientists found the rare amber fossil, and have now confirmed that it contains remnants of spider silk spun roughly 140 million years ago by an ancestor of modern orb-weaving spiders.<br />
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After slicing the amber into thin sections and examining each piece under a high-powered microscope, the researchers discovered that the ancient silk threads share several features common to modern spider webs, including droplets of sticky glue used to hold the web together and capture prey.<br />
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According to paleobiologist Martin Brasier of Oxford University, the gooey droplets suggest that spiders were starting to spin webs that were better adapted for catching flying insects. “Interestingly, a huge radiation took place in flying insects and bark beetles about 140-130 million years ago,” Brasier wrote in an email to Wired.com. “So we may be seeing a co-evolution of spiders and insects here.”<br />
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The new discovery is the first example of an amber fossil from the early Cretaceous period, when dinosaurs like spinosaurs and psittocosaurs roamed the Earth.<br />
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spider-16x-20“Silk is a relatively delicate material and it is rarely preserved in the fossil record, except when entombed in amber,” Brasier and colleagues wrote about the discovery in the Journal of the Geological Society.<br />
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The researchers think pieces of organic material, including the spider silk, became embalmed during a severe wildfire, when amber resins seeped out from the charred bark of coniferous trees and were eventually swept away by flooding.<br />
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In addition to ancient spider silk, the amber chunk contains well-preserved soil microbes, including the oldest known examples of actinobacteria, a common type of bacteria that plays a major role in soil formation.<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The study was published in the Journal of the Geological Society. </span></i></u></div>

Oldest Preserved Spider Web Dates Back to Dinosaurs

Baltic amber. Photo: Brocken Inaglory The world’s oldest known spider web has been discovered on a beach in Sussex, England, t...

Stunning Tanzanite Crystal

Minerals 12:19 PM

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<i><b><span style="font-family: "georgia" , "times new roman" , serif;"><span style="background-color: white; color: #141823; font-size: 14px; line-height: 18px; text-align: right;">Stunning Tanzanite  Crystal . Photo : © Malte Sickinger</span></span></b></i></td></tr></tbody></table><div class="separator" style="clear: both; text-align: center;">
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<span style="font-family: "georgia" , "times new roman" , serif;"><b><span class="fbPhotosPhotoCaption" data-ft="{"tn":"*G","type":45}" id="fbPhotoPageCaption" tabindex="0"><span class="hasCaption"><span dir="ltr">Sensationelle Matrixstufe </span></span></span></b></span><br />
<br /><span>Tanzanite is the blue and violet variety of the mineral zoisite, 
caused by small amounts of vanadium. Tanzanite belongs to the epidote 
mineral group. Tanzanite is only found in Tanzania, in a very small 
mining area near the Mererani Hills.</span><span><span></span></span><span style="font-size: small;"><span style="font-family: "times" , "times new roman" , serif;"><br /></span></span>
<span style="font-size: small;"><span style="font-family: "times" , "times new roman" , serif;"> </span></span><br /> <span style="font-family: georgia;"><br /> Formula:</span> <span class="Eq0J8 LrzXr kno-fv">Ca₂Al₃(SiO₄)₃(OH)</span>
<span style="font-size: small;"><span style="font-family: "times" , "times new roman" , serif;">

</span></span><br /><span style="font-family: georgia;">System:</span> Orthorhombic <br /> <span style="font-family: georgia;">Colour:</span>  purple, ... <br /> <span style="font-family: georgia;">Lustre:</span> Vitreous <br /> <span style="font-family: georgia;">Hardness:</span> 6 – 7 <br /> <br /> <br /><br /></div>

Stunning Tanzanite Crystal

Stunning Tanzanite Crystal . Photo : © Malte Sickinger Sensationelle Matrixstufe Tanzanite is the blue and violet variety of the mine...

Drones for Geology

Geology, in 2:30 PM

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<span style="font-family: inherit;"><span style="background-color: white; color: #333333; line-height: 18px; text-align: right; white-space: pre-wrap;"> Soon replaced aerial photography. Drones take three-dimensional images by stereoscopic techniques.  They carry video cameras high definition, lasers,  thermal and infrared  cameras, to capture perfect images of the earth.    Soon other images seem </span><span style="color: #333333;"><span style="line-height: 18px; white-space: pre-wrap;">fossils</span></span></span><br />
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<a href="http://1.bp.blogspot.com/-tOaVYclQ68w/U_CRLPZu75I/AAAAAAAABfk/HvbiVRpjLDM/s1600/exploration_drone_fig1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><img alt="Drones for  Geology" border="0" height="425" src="https://1.bp.blogspot.com/-tOaVYclQ68w/U_CRLPZu75I/AAAAAAAABfk/HvbiVRpjLDM/s640/exploration_drone_fig1.jpg" title="" width="640" /></span></a></div>
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<span style="font-family: inherit;">Hydrocarbon exploration inarguably is benefiting from ongoing advances in technology – even if certain technical apparatuses being used appear to belong in a sci-fi movie rather than the oil patch.</span><br />
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<span style="font-family: inherit;">Think drones. Sometimes looking a bit like super-size bugs hovering in the sky, these unmanned aerial vehicles (UAVs) are being used to meet various needs in the industry, proving to be useful both onshore and offshore.</span><br />
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<span style="font-family: inherit;">They can be used, for example, to inspect oilfield equipment and pipelines and to monitor gas flares.</span><br />
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<span style="font-family: inherit;">But their significance for the geologist is the ability to acquire up-close, highly detailed images of outcrops, particularly in high elevations where camera-equipped helicopters entail the usual element of risk along with considerable monetary output.</span><br />
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<span style="font-family: inherit;">Piloted via remote control, the drones are essentially flying robots. They can safely fly at exceptionally low altitudes, enabling their digital cameras to capture extremely high-resolution images of the surface.</span><br />
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<span style="font-family: inherit;">Granted, drones per se are not a new phenomenon, actually being commonplace in the military and in certain law enforcement agencies where they are used for aerial surveillance and myriad other tasks.</span><br />
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<span style="font-family: inherit;">They can be small enough to hold in your hand, or they can resemble actual small-size aircraft. Reportedly, there is one the size of a hummingbird, appropriately called a “nano hummingbird.”</span><br />
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<span style="font-family: inherit;">These oddities are beginning to make serious inroads into the private sector.</span><br />
<span style="font-family: inherit;">This is due in large part to the availability and incorporation of mini-size electronics and special software programs to handle the various data they can gather.</span><br />
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<span style="font-family: inherit; margin-left: 1em; margin-right: 1em;"><a href="http://2.bp.blogspot.com/-JqUmSHVU7BE/U_CSIC7eb5I/AAAAAAAABfw/RfH5XLggtHc/s1600/140221_drone_ap_605.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Drones for  Geology" border="0" height="345" src="https://2.bp.blogspot.com/-JqUmSHVU7BE/U_CSIC7eb5I/AAAAAAAABfw/RfH5XLggtHc/s640/140221_drone_ap_605.jpg" title="" width="640" /></a></span></div>
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<a href="http://www.geologyin.com/">Read also:</a><br />
<a href="http://www.geologyin.com/2015/01/10-reasons-to-be-with-geologist.html">10 Reasons to be with a Geologist</a><br />
<a href="http://www.geologyin.com/2014/07/10-pictures-that-will-make-you-want-to.html">10 Pictures that will make you want to become a Geologist</a><br />
<a href="http://www.geologyin.com/2015/01/killer-minerals-worlds-10-most-deadly.html">The world's 10 Most Deadly Minerals</a></div>

Drones for Geology

Soon replaced aerial photography. Drones take three-dimensional images by stereoscopic techniques. They carry video cam...

Maps Expose Unseen Details of the Atlantic Ocean Floor

ocean, Structural Geology, Tectonic 11:47 AM

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<tr><td class="tr-caption" style="text-align: center;">Maps Expose Unseen Details of the Atlantic Ocean Floor. Credit: National Geographic Maps</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;"> Unseen Details of Seafloor Exposed in These Maps of the Atlantic Ocean Floor </span></h4>
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This distinctive physical map of the Atlantic Ocean floor appeared on National Geographic as a supplement to the map of the Atlantic. The detail of such submarine terrain as continental slopes, abyssal plains, and the mighty Mid-Atlantic Ridge is stunning.</div>
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Groundbreaking map of the ocean floor created by technician Marie Tharp and Professor Bruce Heezen, image via The Earth Institute, Columbia University. Together, Marie and Bruce rewrote 20th century geophysics by creating the first systematic, comprehensive map of the entire ocean floor. This paved the way for general acceptance of the theories of continental drift and plate tectonics.</div>
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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-ATH_esji7aQ/WGJsMlftceI/AAAAAAAAK0E/LnQNdmQyug8STBigqqqY_9q-03ceKsABACLcB/s1600/Atlantic%2BOcean%2BFloor%2BMap%2Bfull.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Unseen Details of Seafloor Exposed in These Maps of the Atlantic Ocean Floor" border="0" height="640" src="https://3.bp.blogspot.com/-ATH_esji7aQ/WGJsMlftceI/AAAAAAAAK0E/LnQNdmQyug8STBigqqqY_9q-03ceKsABACLcB/w486-h640/Atlantic%2BOcean%2BFloor%2BMap%2Bfull.jpg" title="Maps Expose Unseen Details of the Atlantic Ocean Floor" width="486" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Credit: National Geographic Maps</td></tr>
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<span style="color: white;"><span style="font-size: xx-small;"><span style="font-family: "georgia" , "times new roman" , serif;">Unseen Details of Seafloor Exposed in These Maps of the Atlantic Ocean Floor </span></span></span></h3>
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Maps Expose Unseen Details of the Atlantic Ocean Floor

Maps Expose Unseen Details of the Atlantic Ocean Floor. Credit: National Geographic Maps Unseen Details of Seafloor Exposed in Th...

Royal Peacock Opal

Minerals 3:12 PM

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<a href="http://4.bp.blogspot.com/-Vu-OTsh4hys/U-YPkwmBJcI/AAAAAAAABeA/7dM-3DTZ7FM/s1600/la-la-tr-0629-opal-04-jpg-20140724.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Royal Peacock Opal" border="0" height="225" src="https://4.bp.blogspot.com/-Vu-OTsh4hys/U-YPkwmBJcI/AAAAAAAABeA/7dM-3DTZ7FM/s400/la-la-tr-0629-opal-04-jpg-20140724.jpg" title="" width="400" /></a></div>
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Since 1981, the Royal Peacock Opal Mine has been open to the public as a pay-to-dig mine. It has yielded countless world-class precious opal specimens during that time. </div>
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<a href="http://3.bp.blogspot.com/-KrmeZJ2MMxI/U-YQCQ8zOWI/AAAAAAAABeI/WzIq7oRkFSo/s1600/vvopalthe_shoe.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Royal Peacock Opal" border="0" height="175" src="https://3.bp.blogspot.com/-KrmeZJ2MMxI/U-YQCQ8zOWI/AAAAAAAABeI/WzIq7oRkFSo/s400/vvopalthe_shoe.jpg" title="" width="400" /></a></div>
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Royal Peacock Opal

Since 1981, the Royal Peacock Opal Mine has been open to the public as a pay-to-dig mine. It has yielded countless world-class prec...

How Material From the Asthenosphere Is Transformed Into Continental Crust

Tectonic 5:03 PM

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<span style="font-family: Georgia, "Times New Roman", serif;"><b>Asthenosphere</b></span></h4>
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<span style="background-color: white;">A semifluid layer of the earth, between about 40 to 80 miles (100-200 km) below the outer rigid lithosphere (oceanic and continental crust) forming part of the mantle and thought to be able to flow vertically and horizontally, enabling sections of lithosphere to subside, rise, and undergo lateral movement associated with plate tectonics.</span><b><br /></b></div>
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<span style="font-family: Georgia, "Times New Roman", serif;"><b>Ocean crust</b></span></h4>
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<span style="background-color: white;">Part of Earth's lithosphere that underlies ocean basins. Oceanic crust is primarily composed of mafic rocks (rich in iron and magnesium) and are less dense than rocks that underlie continents (continental crust is enriched in silica and aluminum). Ocean crust around the world is significantly younger (less than 200 million years) relative to continental crust which has typically accumulated through the natural refining processes associated with plate-tectonics over many hundreds of millions to several billion years.</span><br />
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<span style="font-family: Georgia, "Times New Roman", serif;"><b>Continental crust</b></span></h4>
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<span style="background-color: white;">The relatively thick part of the earth's crust that forms the large landmasses. It is generally older and more complex than the oceanic crust, and dominantly composed of igneous and metamorphic of granitic or more felsic composition.</span><br />
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<a href="http://2.bp.blogspot.com/-J7EO0HS43tA/U-TYUGJeOCI/AAAAAAAABdw/kZ2R6wwPBVE/s1600/plate_tectonics_model.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt=" How Material From the Asthenosphere Is Transformed Into Continental Crust" border="0" height="480" src="https://2.bp.blogspot.com/-J7EO0HS43tA/U-TYUGJeOCI/AAAAAAAABdw/kZ2R6wwPBVE/s1600/plate_tectonics_model.jpg" title="" width="640" /></a></div>
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<span style="font-size: small;"><span style="font-family: Georgia, "Times New Roman", serif;"><b>Plate tectonic model</b></span></span><br />
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Subduction introduces oceanic crustal rocks (including sediments) back into the Asthenosphere. Water and gas helps low-temperature minerals to melt and rise as, forming new continental crust (less dense than oceanic crust). Floating on the Asthenosphere, the continental crustal materials accumulate, forming continents.</div>

How Material From the Asthenosphere Is Transformed Into Continental Crust

Asthenosphere A semifluid layer of the earth, between about 40 to 80 miles (100-200 km) below the outer rigid lithosphere (oceanic and c...

The Red Lake Natron in Tanzania

tourism 8:33 PM

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<span style="font-family: inherit;">Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, and just north east of the Ngorongoro Crater, in the eastern branch of Africa's immense Great Rift Valley. Nestled between rolling volcanic hills and deep craters, Lake Natron sits at the lowest point of the rift valley – 600m above sea level – and is probably the world's most caustic body of water.</span><br />
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<span style="font-family: inherit;">The lake is fed by the Southern Ewaso Ng'iro River and also by mineral-rich hot springs. It is quite shallow, less than three meters (10 feet) deep, and varies in width depending on its water level, which changes due to high levels of evaporation, leaving concentrations of salt and other minerals, notably sodium carbonate (natron). </span><br />
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<span style="font-family: inherit;">The surrounding country is hot and often very dry and dusty – not very conducive to travel. But for those who do choose to visit Natron, they are rewarded with some of the most dramatic scenery they have ever see in Tanzania. It is said, that the journey alone is worth it for the views.</span><br />
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<a href="http://2.bp.blogspot.com/-6txphVHLS0E/U-IaNdwFCVI/AAAAAAAABdY/SxNr5ijSvXY/s1600/lake-natron-1%5B2%5D.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="358" src="https://2.bp.blogspot.com/-6txphVHLS0E/U-IaNdwFCVI/AAAAAAAABdY/SxNr5ijSvXY/s1600/lake-natron-1%5B2%5D.jpg" width="640" /></a></div>
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<span style="font-family: inherit;">The lake has a deep red color characteristic of those where very high evaporation rates occur. As water evaporates during the dry season, salinity levels increase to the point that salt-loving microorganisms begin to thrive. Such halophile organisms include some cyanobacteria that make their own food with photosynthesis as plants do. </span><br />
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<span style="font-family: inherit;">The red accessory photosynthesizing pigment in the cyanobacteria produces the deep reds of the open water of the lake, and orange colors of the shallow parts of the lake. The alkali salt crust on the surface of the lake is also often colored red or pink by the salt-loving microorganisms that live there.</span><br />
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<span style="font-family: inherit;">The high temperature (up to 41°C) and the high and very variable salt content of the lake does not support wildlife. However it is an important habitat for flamingos and is home to endemic algae, invertebrates and round the margins even fish that can survive in the slightly less salty water.</span></div>
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The Red Lake Natron in Tanzania

Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, and just north east of the Ngorongoro Crater, in the...

Mount Nyiragongo - Virunga National Park

tourism, volcano 11:55 AM

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<span style="font-family: inherit;">Mount Nyiragongo is located inside Virunga National Park, in the Democratic Republic of the Congo, about 20 km north of the town of Goma and Lake Kivu. It is one of the most active volcanoes in Africa, and one of eight volcanoes in the Virunga Mountains. The main crater is about two km wide and usually contains a lava lake which appear in the summit crater.</span><br>
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<span style="font-family: inherit;">Nyiragongo's lava lake has at times been the most voluminous known lava lake in recent history. The depth of the lava lake varies considerably depending on the activity of the volcano. A maximum elevation of the lava lake was recorded at about 3250 m (10,700 ft) prior to the January 1977 eruption - a lake depth of about 600 m (2000 ft). A recent very low elevation of the lava lake was recorded at about 2700 m (8800 ft).</span><br>
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<span style="font-family: inherit;">Not much is known about how long the volcano has been erupting, but since 1882, it has erupted at least 34 times, including many periods where activity was continuous for years at a time, often in the form of a churning lava lake in the crater.</span></div>
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<span style="font-family: inherit;">The lava emitted in eruptions at Nyiragongo is often unusually fluid, possibly due to the presence of melilite nephelinite, an alkali-rich type of volcanic rock having unusual chemical composition. Because of the extreme fluidity, Nyiragongo's lava flows can race downhill at up to 60 miles per hour (up to 100 km/h), whereas most lava flows at a walking pace and rarely pose a danger to human life.</span></div>
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<span style="font-family: inherit;">Between 1894 and 1977 the crater contained an active lava lake. On 10 January 1977, the crater walls fractured, and the lava lake drained in less than an hour overwhelming villages and killing at least 70 people. Some reports quote much higher figures of up to several thousand people. The hazards posed by eruptions like this are unique to Nyiragongo. Nowhere else in the world does such a steep-sided stratovolcano contain a lake of such fluid lava.</span><br>
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Mount Nyiragongo - Virunga National Park

Mount Nyiragongo is located inside Virunga National Park, in the Democratic Republic of the Congo, about 20 km north of the town of Goma ...

The Devil's Golf Course, Death Valley

tourism 12:49 PM

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The Devil's Golf Course is a large salt pan on the floor of Death Valley, located in the Mojave Desert within Death Valley National Park, in eastern California. Although its exact boundaries are poorly defined, it extends from the vicinity of the Ashford Mill site to the Salt Creek Hills, a distance of about 40 miles. The salt pan is essentially a gigantic, dried up bed of a lake that once covered the valley to a depth of 30 feet. Some 2,000 to 4,000 years ago the lake dried up leaving behind dissolved minerals which, over thousands of years, were sculpted by weathering processes into fantastic shapes. The salt pan is so incredibly serrated that the 1934 National Park Service guide book to Death Valley National Monument stated that "only the devil could play golf" on its surface. Shortly after, the salt pan came to be known as the Devil's Golf Course.<br>
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About 150,000 years ago the present day salt pan was the site of a large, deep lake caused by snow and melting glaciers as far away as the Sierra Nevada. Known as Lake Manly, this body of water reached depths of 600 feet. During this period the majority of the salts that comprise these formation entered the area. At the close of the last Ice Age (about 10,000 years ago) climate change initiated a period of evaporation drying up this lake. Then for a brief period during the Holocene (2,000 to 4,000 years ago) the climate was again much wetter and another shallow lake formed primarily from snow melt in the surrounding mountains and the drainage of the Amargosa River. This time the salt pan flooded to a depth of about 30 feet.<br>
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<span style="font-size: small;">The climate warmed again, rainfall declined, and the shallow lakes began to dry up. As water evaporated, minerals dissolved in the lake became increasingly concentrated eventually leaving a thick salty pool on the lowest parts of Death Valley's floor.</span></div>
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Tectonic Setting of Synorogenic Gold Deposits of the Pacific Rim

Gold, Tectonic 8:37 PM

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<a href="http://2.bp.blogspot.com/-K75rE-uIIzk/U9lhqoPXVRI/AAAAAAAABbM/LaZ2J_cEVQg/s1600/pacific+rim.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Tectonic Setting of Synorogenic Gold Deposits of the Pacific Rim" border="0" height="420" src="https://2.bp.blogspot.com/-K75rE-uIIzk/U9lhqoPXVRI/AAAAAAAABbM/LaZ2J_cEVQg/s1600/pacific+rim.jpg" title="" width="640" /></a></div>
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More than 420 million oz of gold were concentrated in circum-Pacific synorogenic quartz lodes mainly during two periods of continental growth, one along the Gondwanan margin in the Palaeozoic and the other in the northern Pacific basin between 170 and 50 Ma. These ores have many features in common and can be grouped into a single type of lode gold deposit widespread throughout clastic sedimentary-rock dominant terranes. <br /><br />The auriferous veins contain only a few percent sulphide minerals, have gold:silver ratios typically greater than 1:1, show a distinct association with medium grade metamorphic rocks, and may be associated with large-scale fault zones. Ore fluids are consistently of low salinity and are CO2-rich.<br /><br />In the early and middle Palaeozoic in the southern Pacific basin, a single immense turbidite sequence was added to the eastern margin of Gondwanaland. Deformation of these rocks in southeastern Australia was accompanied by deposition of at least 80 million oz of gold in the Victorian sector of the Lachlan fold belt mainly during the Middle and Late Devonian. Lesser Devonian gold accumulations characterized the more northerly parts of the Gondwanan margin within the Hodgkinson–Broken River and Thomson fold belts. <br /><br />Additional lodes were emplaced in this flyschoid sequence in Devonian or earlier Palaeozoic times in what is now the Buller terrane, Westland, New Zealand. Minor post-Devonian growth of Gondwanaland included terrane collision and formation of gold-bearing veins in the Permian in Australia's New England fold belt and in the Jurassic-Early Cretaceous in New Zealand's Otago schists.<br /><br />Collision and accretion of dozens of terranes for a 100-m.y.-long period against the western margin of North America and eastern margin of Eurasia led to widespread, latest Jurassic to Eocene gold veining in the northern Pacific basin. In the former location, Late Jurassic and Early Cretaceous veins and related placer deposits along the western margin of the Sierra Nevada batholith have yielded more than 100 million oz of gold. <br /><br />Additional significant ore-forming events during the development of North America's Cordilleran orogen included those in the Klamath Mountains region, California in the Late Jurassic and Early Cretaceous; the Klondike district, Yukon by the Early Cretaceous; the Nome and Fairbanks districts, Alaska, and the Bridge River district, British Columbia in the middle Cretaceous; and the Juneau gold belt, Alaska in the Eocene. Gold-bearing veins deposited during the Late Jurassic and Early Cretaceous terrane collision that formed the present-day Russian Far East have been the source for more than 130 million oz of placer gold.<br /><br />The abundance of gold-bearing quartz-carbonate veins throughout the Gondwanan, North American and Eurasian continental margins suggests the migration and concentration of large fluid volumes during continental growth. Such volumes could be released during orogenic heating of hydrous silicate mineral phases within accreted marine strata. <br /><br />The common temporal association between gold veining and magmatism around the Pacific Rim reflects these thermal episodes. Melting of the lower thickened crust during arc formation, slab rollback and extensional tectonism, and subduction of a slab window beneath the seaward part of the forearc region can all provide the required heat for initiation of the ore-forming processes.<br />
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<u><i><span style="font-family: "Trebuchet MS", sans-serif;"> The study was published in the journal <a href="https://www.sciencedirect.com/science/article/pii/S0169136897000188" rel="nofollow" target="_blank">Geology.</a></span></i></u></div>

Tectonic Setting of Synorogenic Gold Deposits of the Pacific Rim

More than 420 million oz of gold were concentrated in circum-Pacific synorogenic quartz lodes mainly during two periods of continental ...

Geology In