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The Earth Story

@earthstory / earthstory.tumblr.com

This is the blog homepage of the Facebook group "The Earth Story" (Click here to visit our Facebook group). “The Earth Story” are group of volunteers with backgrounds throughout the Earth Sciences. We cover all Earth sciences - oceanography, climatology, geology, geophysics and much, much more. Our articles combine the latest research, stunning photography, and basic knowledge of geosciences, and are written for everyone!
We hope you find us to be a unique home for learning about the Earth sciences, and we hope you enjoy!
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The Karoo LIP: The Destroyer of Gondwana About 500 million years ago, a huge continent was assembled due to collisions between multiple ancient cratons, or cores of continents. This supercontinent, Gondwana (Gondwanaland) contained what we know today as Africa, South America, The Arabian Peninsula, India, Antarctica, Australia, and New Zealand – give or take that’s something like ½ of the planet’s continental landmass. That large continent held together for nearly 400 million years, and was even joined with a few other large landmasses for a time to create Pangaea. It lasted for about 10% of Earth’s history, and here you’re looking at the leftovers of its killer.

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beautifuldestinations
"Itchy sea doggo in paradise harbour
#antarctica
🇦🇶 Crabeater seals are the most abundant pinniped in the antarctic, but a decline in sea ice and krill populations are threatening the species." The decline is caused in part by an increase in temperatures as our climate warms. There are many ways you can do your part. One ♻️
#SustainabilityTip
: Avoid over ordering food to limit food waste. Food waste plays a role in climate change due to the energy and water it takes to grow, harvest, transport and package the products. (🎥:
@johnbozinov
📍: Antarctica)
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Iceberg B-15 In March 2000 a slab of ice larger than Jamaica broke away from the Ross Ice Shelf in Antarctica - Iceberg B-15. The iceberg was 270km long and 40km wide and took over a decade to melt away, slowly breaking up into smaller and smaller pieces. By late 2011, the iceberg was literally in thousands of pieces, and sections of it were still floating around in 2013. B-15 began to fragment almost as soon as it broke off, and the majority of the fragments began drifting north. Iceberg B-15a (the largest fragment of the iceberg) and iceberg C-16 (an iceberg that was knocked off by B-15) did not drift north, which created a barrier that restricted the northward flow of pack ice. These two large icebergs remained in the area for several years which resulted in very high sea ice concentrations throughout the summer months around Ross Island, higher levels of sea ice to the south east of the icebergs (less open water), and a 40% decrease in primary productivity due to the decrease in open water. The iceberg did create a few problems for the ecosystems in the region, for example organisms that depend on primary production had to travel much further to find food. The penguins in the region had a particularly difficult period because of these icebergs. They had to travel further away from their nests just to get to open water and then travel further in the open water to find food, ultimately meaning they were away from their nests for longer periods of time. This voyage meant that their nests were exposed to predators (mainly Skuas) that feed on the eggs and chicks for much longer. Breeding success was observed to be significantly lower in the years that the icebergs were there, and many penguins shifted their nesting locations further north, closer to the open water. Some penguin breeding grounds were found to be completely abandoned! The calving event produced the largest recorded iceberg and was a rare event, but not unusual. It is estimated that icebergs of this size generally break off every 150-200 years. At the current rate of change the future may see many more icebergs like this, with many Antarctic ice shelves set for rapid disintegration. B-15 is an interesting example of how breakup of ice on the Antarctic continent can lead to temporary increases in ice on the seas around the continent.  -MJA Image credit: Landcare Research (satellite image, retrieved from http://bit.ly/1LQbAEs) and Josh Landis, NSF (Iceberg photo, retrieved from: http://bit.ly/1AF7kWQ). Further reading: http://stanford.io/1FeSFxO

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Original caption: 

Union Glacier camp is a seasonal, remote field camp in West Antarctica. It is one of my favourite places in the world, due largely to the wonderful people that run and pass through the camp.
I have been lucky enough to work there several times, and this film is a very short guide to the camp and some of the people who work there.
For more information about the camp please visit - antarctic-logistics.com/camp/union-glacier-camp/
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Original caption:

“Ant[arctic]A And Beyond” is a small compilation of 4K footage I’ve shot throughout my expeditions, Artist In Residencies, and travels as a landscape and wildlife photographer. Starting with an incredible 1-month Antarctic expedition to the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands, The South Shetland Islands, and the Antarctic Peninsula; followed by my Artist In Residency sailing the high Arctic on a Barquentine Tall Ship with Scientists and other Artists. No adventure is complete without including Alaska, a very special place to me, with footage and imagery from my work along the Chilkat River, Lake Clark National Park, as well as my Artist In Residency with the U.S. Forest Service in the remote designated wilderness areas of Kuiu and Tebenkoff Bay in the Tongass National Forest. I’ve also included a special piece from one of my favorite U.S. National Parks, Yosemite, with footage of the beautiful natural phenomenon known as the “Firefalls.” I close with some personal favorite images taken elsewhere to include the beautiful Great Gray Owl species (Strix nebulosa).
Some of the Southern hemisphere footage I shot in historically significant locations such as Elephant Island, and the resting place of Sir Ernest Shackleton in Grytviken, as well as incredibly remote wildlife locations such as Salisbury Plains and Saint Andrews Bay. Hiking in an active caldera at Deception Island to crossing the Drake Passage simply must be experienced to appreciate.
Sailing the high Arctic on a tall ship full of Scientists and Artists, you experience a collaboration with amazing people from around the world with one common appreciation for expressing the fragility of our natural world.
Legal: - All footage and still imagery is copyright © Eric Esterle ericesterle.com - All music used and listed in the credits is properly and legally licensed. - Public Domain Cylinder recording by Sir Ernest Shackleton is not copyrighted as it was not included in the Copyright Act of 1909 - Alan Watts recording licensed from alanwatts.com
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Underneath the Dry Valleys may not be so dry

A recent study led by a researcher from the University of Tennessee revealed that there are interconnected aquifers beneath the glaciers and permafrost. The briny liquid is about 300m under the surface and around twice the salinity of sea water and of course, is well below freezing (though it stays a liquid due to the salinity and pressure).

To map this groundwater, the team used a new instrument called SkyTEM which can generate images of subsurface environments. It does this by measuring the electrical resistivity beneath the frozen ground, and as liquids, especially salty liquids, are more conductive than ice, soil or rock it is possible to differentiate what lies beneath the surface.

If Blood Falls (see previous post:http://on.fb.me/1FJVyeK) is representative of the groundwater discovered in this study, then it is likely that a rather diverse and large living ecosystem is existing below the Dry Valleys! This is particularly important for understanding the ways in which life might survive on Mars, as the Dry Valleys have conditions remarkably similar to those of Mars.

It is well known that sub-glacial water exists throughout the icy continent, but this is the first time subsurface water has been discovered in areas that are not covered by ice.

-MJA

Image credit: VALMAP

Further reading: http://bit.ly/1I206NM

Reference: Mikucki, J. A., Auken, E., Tulaczyk, S., Virginia, R. A., Schamper, C., Sørensen, K. I., ... & Foley, N. (2015). Deep groundwater and potential subsurface habitats beneath an Antarctic dry valley. Nature Communications, 6.[_

_](https://www.facebook.com/TheEarthStory/photos/a.352867368107647/870438003017245/?type=1&theater#)

Source: facebook.com
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Blood Falls - Dry Valleys, Antarctica

The Blood Falls are named after the bright, crimson red briny liquid that flows from the tongue of the Taylor Glacier. The liquid is stained crimson from the oxidising iron in the water. The iron is sourced from the weathering of the bedrock and is enhanced by microbial action.

This water flows to the surface only a few times per decade, possibly due to to changes in the weight of the ice above it. The water is hypersaline and extremely cold, but still harbours life- in fact is may contain up to 17 different types of microbes! Samples collects show that the liquid has almost no dissolved oxygen either which suggests that the microbes have evolved to make use of sulphate and ferric ions to respire. As the Dry Valleys are the closest that we can get to Mars without actually going there, Blood Falls provides an excellent analogue for studying the potential for life on Mars.

-MJA

Image credit: Peter Rejcek

Further reading: http://bit.ly/1GFIZxf

Source: facebook.com
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Deception Island

This island that is located in the South Shetland Archipelago in Antarctica is aptly named — it gives an insight into its mysterious geologic origins as well as the somber impact of humans in the past century. Deception Island’s unique landscape helped build its utility as a natural harbor. Shaped like an acutely curved horseshoe, the only opening to the large bay in the island’s center is a narrow channel between two tall cliffs named Neptune Bellows. The island’s central depression is due to an explosive eruption that occurred about 10,000 years ago, creating a caldera that eventually became the giant cove known as Port Foster. The volcano is still active today; in 1967 and 1969, there were two consecutive eruptions that destroyed multiple monitoring stations on the island. Remarkably, those eruptions were not predicted, which remains one of the most notable setbacks for the field of volcano monitoring.

The volcanic processes on Deception Island are still an intensely researched topic. For years, researchers hypothesized that the volcanism was due to subduction (where tectonic plates collide with each other) or by a hotspot (a plume of magma that erupts from deep in the mantle up to the Earth’s surface), but geochemical evidence has refuted these propositions. A more recent hypothesis suggests that the South Shetland Archipelago lies on a rift zone, a region where two tectonic plates are moving apart. The active rifting at Deception Island is a serendipitous research location because of the natural harbor that protects researchers from the harsh Antarctic weather. Rifting has also been associated with oil production in the North Sea, so the possible discovery of oil deposits adds an economic boost for tectonic research in the area.

Prior to the signing of the Antarctic treaty that ensured Antarctica be used solely scientific research and outreach, Deception Island was used as a whaling station. With its natural harbor, whalers were able to set up their boilers and oil processing tanks in a natural refuge from Antarctic storms and icebergs. The whaling stations closed down after the Great Depression, but many sovereignties still fought for full control of Deception Island. However, after the unexpected eruptions of 1967 and 1969 that destroyed much of the island’s man-made edifices, attempts to annex the island were quickly abandoned. Besides maintaining its utility as a research base, the Antarctic treaty preserves Deception Island as a tourist attraction, where the bones of exploited whales and rusting vestiges of oil-processing boilers still remain.

-DC

Photo credits: http://bit.ly/1GLnpuS

Learn more about the geology and volcanism of Deception Island: http://bit.ly/1DKhUgO

Deception Island as a former whaling station: http://bit.ly/1CgHAM1

Add Deception Island to your bucket list: http://bit.ly/1DkXjxJ

A little more on subduction zones, hotspots, and rifting zones: http://bit.ly/1KxNnpv

Source: facebook.com
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Totten Glacier – East Antarctica’s Achilles Heel

The East Antarctic Ice Sheet (EAIS) has generally been considered very stable, with little concern for its disintegration compared to the West Antarctic Ice Sheet (WAIS). This is because the vast majority of the bedrock underneath the WAIS is well below sea level which is not a dominant feature of the EAIS. A recent study published in Nature Geoscience has removed this false sense of security in the East Antarctic Ice Sheet.

The team of scientists led by a researcher from the University of Texas, undertook multiple research flights over the Totten Glacier, the fastest thinning section of the East Antarctic Ice Sheet. Totten glacier has been one of the few East Antarctic glaciers that has been shown to be retreating rapidly, however scientists were unsure why. The study found that the retreat is due to warm water making its way underneath, just like many of the West Antarctic.

The Totten glacier is currently losing an amount of ice equivalent to 100 times the volume of Sydney Harbour every year, which is quite problematic as the Totten Glacier is holding back an immense amount of ice in the Aurora Basin that feeds it. (For more on the buttressing effect of ice shelves, see our previous post: http://on.fb.me/1GhocUq)

The scientists used three types of measurements in their flights, including gravitational measurements, radar measurements and laser altimetry. They measured the ice thickness and the pull of Earth’s gravity to determine how far below the ice the seafloor was. They discovered two troughs in the seafloor beneath the Totten Glacier's floating ice shelf which allow warmer water to flow underneath the ice. It seems counter intuitive, but in Antarctica it is common that warmer water is in fact deeper than colder water as the surfaces are covered by fresh water produced by melting ice. This fresh water, although super cooled, is less dense than the salty, warmer waters, and therefore the cold water floats on top.

The potential sea level rise associated with the melting of the Aurora Basin/Totten Glacier Catchment is approximately 3.5m. Parts of the Northen Hemisphere will feel this more, which will be explained in a future post.

-MJA

Image Credit: Calving front of ice shelf: T. van Ommen, Australian Antarctic Division Map: Jamin Greenbaum, Australian Antarctic Division

Further reading: http://bit.ly/1y43SyW

Reference: Greenbaum, J. S., Blankenship, D. D., Young, D. A., Richter, T. G., Roberts, J. L., Aitken, A. R. A., ... & Siegert, M. J. (2015). Ocean access to a cavity beneath Totten Glacier in East Antarctica. Nature Geoscience.

Source: facebook.com
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The Driest Place on Earth.

It's not where you expect. You're thinking of majestic sand dunes along the western edge of the Sahara, or the barren rocky outcrop's of Chile's Atacama desert. The driest place on Earth is in Antarctica: the McMurdo Dry Valleys. Antarctica has been covered in ice for the last 15 million years, and has built up an average ice thickness of 1.9km. The entire continent is cold (as low as -90ºC) and as dry as most deserts on Earth (South Pole average precipitation is 10cm/year). The McMurdo Dry Valleys are even drier. The fact that they have remained ice free, while the rest of the continent has built up thousands of meters of ice over millions of years, tells you just how parched these valleys are.

Their annual average precipitation is zero cm. They are found in the rain shadow of the 1.6km high Transantarctic Mountains. These mountains also act as a barrier to prevent glaciers from flowing into the valleys. Any ice that does form in the valleys rapidly 'sublimates', evaporating directly from solid ice to water vapour without melting. This processes is helped along by bone-dry 'katabatic winds', which form as cold dense air literally falls off the surrounding ice sheets, and rips through the valleys at over 300 km per hour.

Animals that stray too far into the valleys quickly die of dehydration. Rather than rotting, the dry air desiccates and mummifies their bodies, which can be preserved on the valley floor for hundreds or thousands of years (like the seal in the photo). When the explorer Robert Scott discovered these valleys in 1903, he called them the 'valleys of death'.

Since 1903 scientists have had a closer look at the dry valleys, and they are far from dead. All kinds of 'extremophiles' (life that thrives in extreme environments) call the McMurdo valleys home - lichens, mosses, nematodes (microscopic worms) and other microbes are most common.

These frozen deserts are one of the best analogues we have for Martian environments. Studying how life survives there is one of our best ways of understanding how life might exist on other planets.

  • OB

Image Source: - Bull Pass: http://goo.gl/E15f19 - Mumified Seal: http://goo.gl/TtIoqe

Where are these dry valleys?: http://goo.gl/CCnTSd A bit more about them: http://goo.gl/Mj1ZvU The wettest place on Earth: http://goo.gl/7Ge5lE We've talked about these valleys before: http://goo.gl/pAHkY9

Source: facebook.com
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The Weddell Seal

Weddell Seals are true seals, belonging to the group known as Phocidae. They are the most southerly breeding mammal in the world (aside from potential humans), and they are the most well known of the Antarctic seals. They are large, reaching around 3 meters in length and weighing up to half a tonne. The Weddell Seal is a very vocal species - (they sound a little like Darth Vader to me sometimes); even while standing on sea ice several meters thick, you can occasionally hear them underwater below you.

They are extremely competent divers, capable of reaching depths up to about 600m and can remain underwater for up to 82 minutes. They tend to haul out on the fast ice (that is, sea ice that is attached or 'fastened' to land and is not affected by winds or tides). The seals may venture up to 20km out into the Southern Ocean to feed on krill, fish, squid, crustaceans and the very occasional penguin.

Being rather placid and abundant, they are the most studied of the Antarctic seals. When they haul out on the ice, they remain close to their breathing holes where they can easily dive back in. As they spend most of their time on and below the fast ice, their predators are limited. Killer whales, for example, cannot make it far enough under the ice to reach them. This means that the majority of their deaths occur from disease or starvation.

Weddell seals have historically been harvested for their blubber, both as a food source for humans and sled dogs and as a fuel source for past explorers.The Weddell Seal is protected under the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals which would heavily regulate any future harvest of the species, though it's pretty unlikely for that to happen - dogs are no longer permitted in Antarctica, the seals are not very tasty (according to historic journals) and blubber is certainly not the most viable fuel source in Antarctica any more. The convention came into force in 1978 but wasn't entirely necessary, as by that time the commercial value of seals in Antarctica was already quite low. It is unlikely that harvesting of seals will begin again in the near future.

I was fortunate enough to see these two seals poke their heads up through a breathing hole on the sea ice off Ross Island in December when we were out counting them.

-MJA

Image credit: My own http://smu.gs/1E2hkL4

Further reading: http://bit.ly/1D0d3rr

Source: facebook.com
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mobile__museum🇪🇸¿Qué está haciendo este fósil preparatorio? Está usando una herramienta llamada micro-jack para descubrir un reptil herbívoro terápsido llamado Lystrosaurus. Este reptil vivió hace 250 millones de años durante el Era Triásica. Este fósil fue encontrado en el Monte Shenk en la Antártida. • • • 🇬🇧 What is this fossil preparator doing? He’s using a tool called a micro-jack to uncover an ancient therapsid reptile called a Lystrosaurus. It lived 250 million years ago during the Triassic Era and was found on Mt. Shenk in Antarctica.
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