Tuesday, January 20, 2015

Ancient Scorpions may have Lived in Water but Walked on Land

Paleontologists have hypothesized that scorpions evolved on the seafloor, but some recently discovered fossils have scientists reconsidering exactly how it happened. Eramoscorpius brucensis, possibly the second oldest known scorpion at 430 million to 433 million years old, appears to have lived primarily in water and occasionally spent time on land, putting scorpions on dry ground much earlier than previously thought.

There’s a clear evolutionary advantage to spending time on land – scorpions molt, and they’re extremely vulnerable during the process; leaving the sea would allow them to avoid predators until their new exoskeleton formed. However, walking on dry ground requires having land-legs.

Before E. brucensis, ancient scorpions had leg structures similar to those of crabs (horseshoe crabs are one of the closest living relatives of ancient scorpions), and, like crabs today, moved around on the tips of their foot segment. They would’ve needed water to help support their weight. E. brucensis had a leg structure similar to what scorpions have today; meaning their legs could’ve supported their body on land. So why not just live on dry ground? Their digestive systems lacked coxapophyses, which helps modern scorpions consume prey on land, suggesting E. brucensis still needed to eat in the water.

Further evidence of this dual existence comes from the quarries in Ontario where most of the fossils are from. They’re filled with fossils of sea creatures, suggesting E. brucensis mostly lived in the water as well. However, the rocks surrounding the scorpions have ripples that imply brief exposure to air. Also, the position of the fossil scorpions suggests empty molted exoskeletons rather than a carcass, and it’s much easier for exoskeletons to fossilize on land than in the sea.
If E. brucensis did indeed live in the water and walk on land, then scorpions developed their first adaption for living out of the sea much earlier than previously thought. The evolution of scorpions is still under debate and more research is needed.

Photo Credit: David Rudkin, Royal Ontario Museum

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Ridiculous storm photo !

Astronaut Sam Cristoforetti arrived on the International Space Station in November. From my perspective, she had some big shoes to fill in terms of photography; astronauts Reid Wiseman, Alexander Gerst, and Chris Hadfield set a high bar in finding and capturing spectacular and artful scenes of the planet Earth out the ISS windows. 

These photos of Tropical Cyclone Bansi are remarkable and some of the most amazing shots from the ISS yet. In the first off-center photo, the light bursts illuminating the storms eyewall are lightning, the light is bouncing from side to side off of the wall clouds. The faint green band is airglow – light released from ionized oxygen heated by the sun.

In the second photo, taken directly above the storm, a lightning burst flashes near the eye of the storm and some of the light from that bolt has slipped across the clouds of the eyewall to illuminate the hole in the storm.

This storm is expected to remain out to sea and weaken without threatening land. Make sure you followhttps://twitter.com/AstroSamantha on that network to see if she can find a better shot than these. That will take some effort. 

Did the mega volacano kill the dinosaurs ?

The Cretaceous-Paleogene/Tertiary extinction event (K-Pg or K-T as it is known by geologists) was previously thought to be the only mass extinction out of the “big five” not attributable to volcanism. Instead, the currently accepted theory linked a meteorite impact near present-day Chicxulub, Mexico as the lone cause (known as the Alvarez hypothesis), although there is growing support for volcanic activity as a second major factor. Now, new research led by Brian Schoene of Princeton University has added further evidence that non-avian dinosaurs were actually wiped out by volcanism rather than a meteorite collision some 66 million years ago, confirming what some geoscientists, such as Dewey McLean, long suspected.

The Deccan Traps, a massive flood basalt in India, has long been known as a series of volcanic events that occurred at around the time of extinction, but the majority believed that they erupted too early on to have had a significant effect. Scientists have now tightened the timeline of the main sequence of eruptions, which now appear to have happened very soon before - geologically speaking - the extinction, with new precision rock dating evidence (using U-Pb dating in zircons) showing that the main phase of eruptions occurred within 250,000 years of extinction, rather than millions.

This new timeline is very important, as the volcanic gases now believed to be responsible for dramatic, extinction-inducing climate change (particularly sulfur dioxide) would have been released very shortly before, and during (up to 750,000 years) the time of the K-Pg extinction. It adds weight to the idea that volcanism was the primary cause of extinction, with the meteor impact as the icing on the cake. During it's active phase, the Deccan Traps volcano released over 1.1 million km3 (264,000 cu mi) of lava, with layer upon layer of basalt culminating in a depth of 2,000 m (6,562 ft) thick. Since then, it has gradually been eroded down to 512,000 km3 (123,000 cu mi).

Scientists are now working on further constraining the timing of eruptions and using this data to refine computer-based environmental change models. This will enable researchers to better determine the individual as well as cumulative effects of Deccan Traps volcanism and Chicxulub meteorite impact on Earth.

Past articles:
Deccan Traps: http://on.fb.me/1ByYtnX &http://on.fb.me/1ByYtnX
Did a comet cause extinction?:http://on.fb.me/14FWelu
K-Pg event: http://on.fb.me/1xuvbk5 &http://on.fb.me/1uaQff9
end-Permian extinction event - http://tmblr.co/Zyv2Js18raAV1
Image credit: by Nichalp, 2007 (http://bit.ly/1B8kHyg) Used under CC licensing.

Further reading:
Deccan Traps - http://bit.ly/1BcXWcx &http://bit.ly/1sHvLzn
Did the Traps wipe out the dinosaurs?http://bit.ly/1G4hEKz & http://bit.ly/17QFBWo
Original paper by Schone et. al. - http://bit.ly/1C66iS8(paywalled)

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Tuesday, September 23, 2014

Magnificent Mayon

Held by some to be the most perfect stratovolcanic cone in the world, the Philippines' most active volcano last erupted just over a year ago (see our coverage of the latest of the 48 recorded eruptions in the last 400 years at http://tinyurl.com/mcporfd). Rising 2,462 metres high on the main island of Luzon, it has been a national park since 1938 and has played an important part in the history and culture of the island. It is named after a heroine in a local legend who eloped with her lover. The gods buried the furious father who was chasing them under a landslide.

The magma feeding this smoker is born deep below, as the Philippine oceanic crust subducts beneath the Philippine continental plate (formed of a belt of continental fragments). When the plate reached a certain depth, and set of pressure/temperature conditions, the water in the altered seafloor basalt is literally baked out of the minerals it was locked in, and lowers the melting point of the mantle wedge above, causing it to partially melt and the resulting less dense magma rises towards the surface through a line of weakness such as a fault in the overlying crust.

The cone is formed of layers of welded ash from pyroclastic flows alternating with layers of lava that oozed out of the volcano over the millennia of its geological history. Its products are classified as basaltic andesite, lavas being graded according to richness in silica.

Sitting above the city of Legaspi, the mountain has several associated hazards, ranging from lava and pyroclastic flows (clouds of very hot air and ash running down the ravines carved into the cone by tropical rains from typhoons) during eruption to subsequent lahars, flows of running mud that rush down river valleys when downpours mix with the fine ash, obliterating everything before them. The rain from Typhoon Durian killed over a thousand back in 2006. Its most powerful recorded outburst buried the town of Cagsawa in 1814.

Image credit: Dacel Yazon Andes


Kaieteur falls

This waterfall is Kaieteur Falls, found in the nation of Guyana within Kaieteur Falls National Park. 

This waterfall sits on the Potaro River, a tributary of the Essequibo River that drains a large portion of South America north of the Amazon Basin. 

The falls cascade over cliffs made of conglomerate and sandstone, dropping over 225 meters in the initial fall. These falls aren’t either the biggest or tallest in the world, but the drop is 4 times the height of the well-known Niagara Falls and twice the height of Victoria falls. These falls are therefore one of a few found globally that have both a very large drop, a high flow rate, and a narrow focus in its canyon, giving the waters pouring over the cliff immense power by the time they reach the base.

Image credit: Cody H (creative Commons):

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Sunday, July 6, 2014

Mount Fuji - Japan

You cannot help but be calmed by this beautiful shot of Mount Fuji, looking over Lake Kawaguchi. 

Indeed such is the beauty of this volcano that TES has posted pictures and stories of it in almost every situation:

sunset: http://on.fb.me/1lgGLJM
moonlight: http://on.fb.me/1qecbs5
under a comet: http://on.fb.me/1yR3juK
from space: http://on.fb.me/1qydsaT
under a cloud: http://on.fb.me/1mhqAfn
and even the chance to climb it using Google Street View: http://on.fb.me/1qKNsLX

The Japanese football team’s dreams of rising majestically above the competition will have to wait until four years time, as they finished bottom of a tough Group C. They were tipped to perform well, but football is often unpredictable, just as volcanic activity can be.

Many factors are taken into account in trying to predict volcanism, which can be read about in relation to Mount Fuji’s individual situation here: http://on.fb.me/1nKVKNH and more generally here: http://on.fb.me/Tm3lKa .

Image credit (non commercial): Masaru Minoya (http://bit.ly/1lgDKsU)

Sunrise over Lake Malawi

Lake Malawi sits near the southern end of the East African Rift Zone and borders the nations of Malawi, Mozambique and Tanzania. Some of the bordering countries refer to the lake as Lake Nyasa, using the name that predated the founding of Malawi as a country.

The lake sits in a tectonic basin being formed as the eastern side of Africa pulls apart. The East African Rift Zone is a feature formed over the last several million years as tectonic forces are splitting the very continent apart. On land, these forces result in the formation of rift valleys; deep, linear valleys surrounded by steep cliffs and normal faults. Some of those steep cliffs can be seen in the far distance in this photo.

Lake Malawi National Park sits at the southern end of this lake in Malawi and has been declared a UNESCO world heritage site due to the setting, surrounded by the scarps of the Great African Rift Valley, and due to the variety of fish and other wildlife sustained by its waters.

Image credit: http://www.fotopedia.com/items/flickr-2368169377
(Creative commons)

Tuesday, June 24, 2014

Klyuchevskaya Sopka

Hell yeah, that’s a volcanic eruption as seen from space.

To be more precise, it is the eruption of Klyuchevskaya Sopka taken by the Space Shuttle Endeavour on the 30th of September 1994.

Impressive, isn’t it eh?

This particular eruption expelled ash and gases upwards of 18,300 metres above sea level and the winds carried the ash as far as 1,030 km. Looking at this image and reading just how enormous the eruption was, it is easy to understand why some people link current climate change with events like volcanic eruptions. But, what role do volcanoes actually play?

As we can see, during major volcanic eruptions huge amounts of volcanic gas, aerosols and ash are injected into the stratosphere. The ash tends to fall fairly rapidly from the stratosphere; a matter of days or weeks and has little implication on the climate. However, volcanic gases like sulphur dioxide can cause global cooling and volcanic carbon dioxide, the infamous greenhouse gas, has the potential to promote global warming.

Perhaps contrary to belief, the most significant climate impacts of volcanic activity are as a result of sulphur dioxide. Sulphur dioxide gas is converted to droplets of sulphuric acid in the stratosphere over the course of a week to several months after the eruption. Winds in the stratosphere spread the aerosols until they practically cover the globe. As the droplets have a high albedo, they reflect sunlight reducing the amount of energy reaching the lower atmosphere and the Earth's surface; cooling them. (NASA,1996)

Once formed, these aerosols stay in the stratosphere for around 2 years, although data from NASA’s stratospheric Aerosol and Gas Experiment (SAGE II) showed the effects of the eruption of Mt. Pinatubo in 1991 lingered for up to 10 years.

As mentioned previously, carbon dioxide is also emitted during volcanic eruption and a question that has commonly been asked is “Don’t volcanoes contribute much more CO2 emissions than human activities?

Unfortunately the answer to that question is a clear and unequivocal “No”.

Published reviews of the scientific literature by Kerrick et al (2001) report a minimum-maximum range of emission of 65 to 319 million tonnes of CO2 per year from subaerial and submarine volcanoes.

This seems like a huge amount, and it is. That is, until we compare it to anthropogenic emissions.

According to an International Energy Agency some 30. 6 billion tonnes of carbon dioxide were released into the atmosphere as a result of human activity in 2010.To say that another way, assuming the highest estimates of volcanic CO2 emissions (319 million tonnes), human-emitted carbon dioxide levels were more than 95 times higher.

The Mount Pinatubo eruption in 1991 emitted 42 million tonnes of CO2 (Gerlach et al 1996). Now, compare this to human emissions in 1991 which were a total of 23 billion tonnes of CO2 (CDIAC). The strongest eruption over the last half-century amounted to 0.2% of human CO2 emissions in that year. 0.2%.

Image courtesy of NASA


Carbon Dioxide Information Analysis Centre:http://cdiac.ornl.gov/trends/emis/overview_2006.html

Kerrick, D. M. (2001). "Present and past nonanthropogenic CO2 degassing from the solid earth." Rev. Geophys. 39(4): 565-585.

NASA,1996; “Atmospheric Aerosols: What Are They, and Why Are They So Important?”

Terrence M. Gerlach(1996) Pre-Eruption Vapor in Magma of the Climactic Mount Pinatubo Eruption: Source of the Giant Stratospheric Sulfur Dioxide Cloud . http://vulcan.wr.usgs.gov/Projects/Emissions/Reports/Pinatubo/pinatubo.html

Annular Eclipse

Almost 14 days ago, there was a lunar eclipse visible in the Western Hemisphere. A lunar eclipse takes place when the Earth is directly between the Moon and the Sun. It takes the Moon 28 days to orbit around the Earth, so 14 days after a lunar eclipse, the Moon is on the opposite side of the Earth, between the Earth and the sun.

If the angles line up correctly, that’s the day when a solar eclipse is possible, and on April 29th, there will be an annular eclipse of the sun. Unfortunately the eclipse will be best viewed from remote areas in Western Australia, the southern Indian Ocean, and Antarctica, but populated areas in Eastern Australia may be able to see up to about 60% coverage just before sunset on Tuesday.

An annular eclipse occurs when the Moon blocks out most, but not all, of the sun’s disk. The moon’s orbit around the Earth is not circular, so at some times it’s closer to the planet and other times it’s farther away. An annular eclipse happens when the moon is at a point in its orbit far from earth, making the moon’s disk small enough to allow this “ring of fire” around the edge.

As with most eclipses, it is not safe to view this eclipse with the naked eye; you will cause eye damage if you look. Standard sunglasses also do not provide enough protection. Instead, eclipse-viewing glasses, welding shields, cameras, or other viewing devices will be required for save viewing.

Image credit: t-mizo (creative commons license): previous annular eclipse viewed from Japan

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Nohkalikai Falls

During the monsoon season, this area of the north eastern Indian state of Meghalaya near Cherrapunji has been named the wettest place on Earth. All that water has to go somewhere, and several of the Subcontinent's tallest falls are located in the area. The monsoon gathers during the spring as the land bakes, causing a column of rising air that pulls moist sea air behind it, bringing the annual rains on which Indian civilisation has depended since pre Vedic times.

Nohkalikai is supposedly the tallest plummet in India, at around 340 metres, and at the right time of year one of the most powerful. The crashing waters have carved out a deep rock pool at the bottom of the plateau that changes colour from blue to green depending on the season. The rocks are a Cretaceous-Paleogene sedimentary stack made of limestone and sandstone.

The name (jump of Ka Lilai) is associated with a tragic legend of a woman who went mad after a family tragedy and threw herself off the cliff. During the dry season thee falls slow to a trickle. They sadly often hide in cloud during the monsoon season when at their most spectacular.

Image credit: Sunanda