The Earth Story

The Geikie Plateau lavas

The Eastern coast of Greenland starts off somewhat smooth, traveling northeast from the huge island’s southern tip, with only occasional outlet glaciers draining the large icecap. It then reaches one more tip, a Peninsula holding what is known as the Geikie Plateau, before turning due north with a much more dissected, channel-filled coastline.

These rocks come from the Geikie Plateau and they illustrate some of the processes that went into forming Greenland as it exists today. These layered rocks are the remnants of a huge outpouring of lava about 60 million years ago.

These rocks date back to the time when the northernmost Atlantic Ocean opened. The continents were spreading to the south well beforehand, but Greenland finally pushed away from Scandanavia and Scotland at that time. The fairly sharp coastline along Southeastern Greenland is a testament to this fairly recent geologic event; there hasn’t been much time since the ocean opened for deeply incised channels to form, leading to a fairly smooth coastline still partially defined by the locations of tectonic rifting.

A thick pile of lava like this doesn’t make it to Earth’s surface easily. These rocks bear chemical signals suggesting that they relate to the Icelandic Large Igneous Province or the Icelandic plume – the same surge of magma that built these rocks today builds Iceland to the East.

A big blob of hot rocks wants to rise up towards Earth’s surface, but it can have a tough time getting there if a continent is in the way. Sometimes the continent will melt, sometimes the continent can even be pushed apart.

Since these rocks formed at the same time the ocean opened, the continent itself was probably wedged apart and pushed open by the hot, rising mantle that melted to form these thick lava sequences that now dot the Greenland coast.

The final ingredient here is, of course, ice, which has sculpted the terrain. Sharp shapes like the mountain at the center are called horns: they are carved by glaciers that flow down all sides from a central peak. The valleys in the foreground are snowed in, but at the bottom its almost certain that their bases would have a U-shape, carved by the weight of huge glaciers moving through them during previous ice ages.

-JBB

Image credit: https://www.flickr.com/photos/gsfc/7166013678/

Sources: http://www.sciencedirect.com/science/article/pii/S0024493708002260 http://blogs.ei.columbia.edu/2011/04/28/a-30-year-history-of-measuring-greenlands-breathtaking-vistas/

Moonrise over the Atlantic Taken from New Jersey in order to evade light pollution, an amazing photo of the galaxy and rising Luna over the Atlantic ocean is a true feast for the eyes. Loz Image credit: Jim Abels

Neat work - timelapse shots of the Milky Way taken out the front window of a plane flying from Spain out over Africa and the Atlantic Ocean, with cities and light sources in the clouds below labeled. 

The Canary Islands from space.

NASA astronaut Karen Nyberg shot this amazing picture of these volcanic islands, along with Von Karman vortices in the clouds flowing around them. These form as masses of air split around protruding objects such as islands sticking out of the sea. Only four of the seven main islands are visible.

Loz

Image credit: K. Nyberg.

Real time drone-captured video of Aurora Borealis over Iceland shores last week.

Atalanta, pulsing... Blowholes happen when the power of the waves smashing and booming in a cliff cave (erode a pathway to the surface and shoot up a jet of water with each passing wave. In this slow motion movie, taken at the Bufadero de la Garita on Gran Canaria the usual lightning speed is transformed into a dance of water, air and power. The cave is a lava tube, formed when a crust of magma froze at the surface of the flow, allowing the liquid rock underneath to flow in its own homemade 'river channel' towards the Atlantic Ocean. Loz Image credit: Simone Mainetti Simone's facebook page: http://bit.ly/1sliCxj http://bit.ly/1TRKDFg http://bit.ly/1T81bdl

Earthrise 2

The original Earthrise image taken by astronaut William Anders aboard the moon circling Apollo mission in 1968 is one of the most iconic of the 20th century and was called “the most influential environmental photograph ever taken” by nature photographer Galen Rowell (see http://on.fb.me/1Yu6VwN). NASA have just released this stunner of a pic taken by the robotic exploration mission currently circling our airless moon. Our planet is seen from the spacecraft's perspective with the field of view centred over the Atlantic Ocean with the rim of farside lunar crater Compton in the foreground.

The Lunar Reconnaissance Orbiter was launched in 2009 and sees 12 such Earthrises daily, spending most of it scanning our satellite's surface. On occasion, the satellite is pointed into space, to observe such minimalist atmosphere as Luna possesses, or to calibrate its instruments, and when our globe passes in front a series of photos like this one can be taken and stitched into a composite using data from both the high res black and white and lower res colour cameras..

Loz

Image credit: LRO/NASA

http://go.nasa.gov/1Pd9Ycj

This is simply a gorgeous data visualization. These flow paths show currents in the Mediterranean Sea and the northeastern Atlantic Ocean over an 11 month period. Darker lines are flow at depth, brighter lines are flow near the surface. So many different eddies and flow paths, in addition to the major currents that carry water into and out of the Sea.

Gondwana Cratons

A Craton is an ancient piece of earth’s continental crust, one that has been stable for billions of years.

The Earth naturally contains elements that give off heat, such as radioactive potassium, thorium, and uranium. When the mantle melts, those elements move into the melt, extracting them from the mantle and moving them upward. Once those elements are concentrated in the crust, the heat can rapidly escape out into space. Once that heat is removed, the crust can become cold and stable, hard to deform.

The earth has over a dozen ancient cratons; they form the core of many of the continents. Cratons are surrounded by mobile belts; areas that stay active and occasionally collide. Continents can grow either by assembling several cratons during continental collisions or by building wider mountain ranges on their edges. Both of these can be seen in the general map of Gondwana; the Andes mountains are a place where the continent is growing outwards while the heart of Gondwana contains a series of ancient, Precambrian-aged cratons.

When Gondwana rifted apart in the Jurassic, several of the old cratons were completely torn apart. Rocks from these cratons can be found on both sides of the Atlantic today. Tearing apart a craton requires adding heat back in to weaken the old crust; this heat could be added if a large plume of extra-hot material rises from deeper in the mantle and pushes the craton apart. We find evidence of these plumes today – such as in the igneous rocks found in the famous Iguazu falls (http://tmblr.co/Zyv2Js1ffrKej).

-JBB

Image credit: https://wikimediafoundation.org/wiki/File:Cratons_West_Gondwana.svg

Read more: http://www.sciencedirect.com/science/article/pii/S0301926812002173 http://bit.ly/1VGk6fx

Birth of the Atlantic

This is a gorgeous computer rendering of the opening of the Atlantic Ocean and the breakup of the Supercontinent Pangaea.

During the Triassic and Jurassic, North America began rifting from the part of Gondwana (today Africa) that it had collided with to build the Appalachian Mountains and later during the Jurassic, the huge block of South America and Africa that had been linked together for hundreds of millions of years also separated.

The breakup of a Supercontinent can have many causes. Plates far away can be pulled down into the mantle and a rigid plate could transmit stress to weak points far away, causing the plate to pull apart. Alternatively, something could wedge its way in-between the plates and force them apart; both of these breakups occur at the same time as huge outpourings of volcanic lava, maybe suggesting that a hot plume of mantle material rose up and pushed them apart. The arrows that appear and change on each plate show how the plate motion directions change as these different forces interact. The longer the arrow = the faster the plate is moving.

The plate motions of the past 200 million years or so are known extremely well because of magnetic anomalies. When new seafloor is created at a mid-ocean ridge, that seafloor records the direction of the Earth’s magnetic field at the time. As the rocks move away from the ridge, they preserve a record of where on the planet’s surface they formed. By mapping out magnetic anomalies across the planet’s ocean floors, we find a record of how the oceanic plates move.

That record only goes back about 200 million years because that’s the oldest oceanic crust on Earth. Almost all the oceanic crust older than that age has cooled off so much and become so dense that it has readily subducted, heading down into the mantle to start the cycle again. The age contours in this plot let you see how that age progression happens; new crust formed at mid-ocean ridges and then older crust vanishing beneath subduction zones like those on the western side of North and South America.

-JBB

Video Credit: NOAA http://sos.noaa.gov/Datasets/dataset.php?id=569

The Most Isolated Island in the World – Bouvet Island  Go to Iceland, turn south on the Mid-Atlantic Ridge and follow it all the way to the triple junction where the ridge intersects the Antarctic Plate, and there you will find… an island. At 2260 kilometers from the nearest inhabited island (Tristan de Cunha with a population of 271, if this counts), smack dab between Africa, South America and Antarctica, Bouvet island is not a very big island, less than fifty square kilometers in size with nearly all of it covered by a glacier, but is considered as the most isolated land mass on earth. Nevertheless, it turns out to be – an island of mystery! Discovered in 1739 by the French (hence the name), claimed by the British in 1825, and annexed by Norway in 1928, there has never been a war or disagreement about the sovereignty of the island – apparently no one loves it enough to argue over it, and it is, today, a nature reserve (apparently seals and penguins do like the place). The Norwegians take responsibility for it, with the island’s administration managed by their Polar Department of the Ministry of Justice and the Oslo Police. Since the island is uninhabited, the police have little to do there one supposes. Perhaps in hopes that someday someone would like to take up residence, an internet domain has been set up under its name (.bv), but as yet no takers. The average high temperature on Bouvet Island is just above 1C, and average low temperature is -2.3C – we know this because there is an automated weather station on this desolate locale. Nor is the island forgotten by the seismographs of the USGS who keep track of all earthquakes in the world, even those in Norwegian territories in the South Atlantic, and spotted a 5R earthquake near there (well, “near” as distances go for the most isolated spot in the world, about 348km west of the island) in 2009. Since geologists never forget about any island, no matter how great or how small, there are geologic papers on Bouvet Island that describe its volcanic composition (sitting on the Mid-Atlantic Ridge, not surprisingly these include Mid-Atlantic Ridge Basalts – “MORB”.) The island is as close to the site of a plate tectonic triple-junction as can be: it’s just on the edge of the African Plate next to the South American plate border (the Mid-Atlantic Ridge marking this), intersecting with the Antarctic plate. The island’s volcano has been hypothesized to be a “hot spot” where material is coming directly from the mantle. This tectonic environment is “way cool” for a geologist, and perhaps were there not so many glaciers occluding the island, some poor lost PhD student would have a great time in the frigid field. Some mysteries surround the island: an abandoned boat stocked with supplies (but no passengers) was found there in 1964; in 1979, a US satellite saw an extremely bright light flash from the uninhabited area near the island that is speculated to have been a nuclear bomb test by the Israelis and South Africa (come on, conspiracy theorists! You can do better than this!); AND there’s a disappearing island nearby!  Unlike Sandy Island in the Pacific that probably never existed in the first place (as recently reported by The Earth Story), Thomson Island was “discovered” to the northeast of Bouvet Island and seemed to exist in 1825 and 1893 (including very convincing sketches), but hasn’t been sighted since at least 1927. Possibly Thomson Island, also theoretically on the Mid-Atlantic ridge, could have been destroyed in an eruption or some caldera collapse, but in the 1960’s sonar failed to locate any sort of submerged shoal – since the original coordinates of the island’s position were done with the cutting-edge technology of 1825, possibly the sonar was looking in the wrong place.  Since the Norwegians haven’t yet sent out the Oslo Police to figure out who may have stolen the island, all theories are still open.  Annie R. Photo credit: We delightfully note that Google Panoramio has even made it to the most desolate island on earth and this photo is by: Franco Cain on Google Panoramio http://wikitravel.org/en/Bouvet_Island https://www.cia.gov/library/publications/the-world-factbook/geos/bv.html http://www.atlasobscura.com/places/bouvet-island http://www.antarctic.ac.uk/documents/bas_bulletins/bulletin13_06.pdf http://on.fb.me/1Ceod9v http://link.springer.com/article/10.1007%2FBF00451868?LI=true

An Sgurr Some 58 million years ago the area we now know as the Hebrides (a group of Islands off Scotland) were a place of fire and smoke rather than the present windy sea lashed locale of the present era. The North Atlantic Ocean was opening, completing the bustup of Pangaea. This sundering of the European and North American plates was accompanied by huge outpourings of lava over a wide region, whose remnants still dot the landscape from Greenland to Ireland, Canada to Scandinavia.  This 5km long ridge on the isle of Eigg is what remains of a hug pyroclastic flow from a large eruption, whose main vent was located at the present isle of Rum. An Sgurr is also a textbook example of what geomorphologists (those who study the surface shape of the Earth and how it came to be) call inverted topography, a process whereby what were once lowlands turns into highlands due to an interaction between the constraints imposed by the underlying geology and the forces of erosion.  When the silica rich rhyodacitic lava erupted, the hot molten ash and rock flowed from the vent down a river valley, filling it to a height well above the 400 metres of the uneroded remnants that we see today. The rock is dark (unlike most silica rich volcanic rocks) because it is a quick cooled variety known as pitchstone with a high glass content, but coarser and with more crystallinity than the more familiar obsidian. It looks like a glassy matrix, filled with angular crystals. Our ridge is the largest exposure of such rock in the UK, and it displays typical lava cooling features (such as columnar jointing similar to the Giant's Causeway). Pitchstone also happens to be very resistant to erosion, the result of its peculiar part glass part crystal structure, and over the aeons since it was emplaced, the basaltic rocks (also from the growing continental rift) around it have melted away under the assault of wind, frost and wave, leaving the fossilised impression of a whole Palaeocene river bed standing proud as a tall ridge, complete with its rounded boulders and tree fossils at the base. Solitary mountains like An Sgurr (the notch) are known as inselbergs, but they form by a variety of processes, and most are not inverted.  Loz Image credit: James Gray http://www.geograph.org.uk/snippet/11009 http://www.isleofeigg.net/an_sgurr.html http://www.summitpost.org/an-sgurr/195034

Lava drips This wall has been painted by lava, literally. This is an outcrop of rock on Lanzarote Island, the easternmost of the Canary Islands in the Atlantic Ocean.  The Canary Islands are volcanic. Each hosts at least one, if not several craters active within the last 10 million years or so, and several are historically active.  This wall had lava flow past it and stick. Flowing basaltic lava is a somewhat sticky substance, like syrup. It can still flow in waves and actually lap up against objects, but if the lava drains away, lava stuck to the walls will begin to drip downward. You could probably imagine what this would look like if you sprayed syrup against a vertical wall or object (the Earth Story does not recommend you do this and will not help you clean up afterwards). Since it is lava, as those drips flow downwards, they lose heat, cool, and solidify, locking them in place for photographers to find. The different layers you see on the wall almost certainly reflect different lava depths as whatever flow passed along these walls waxed and waned in volume. The reddish and greenish/blue colors reflect different degrees of alteration of iron-bearing minerals in the rocks. -JBB Image credit: https://www.flickr.com/photos/torrelodones/7160317366/in/photostream/ See more: http://www.whoi.edu/hpb/viewPage.do?id=153

The Milky Way and Bioluminescence If I could put two of my favourite things in a photo, this would be the result. Captured by Fefo Bouvier, this absolutely incredible image shows both the Milky Way AND bioluminescent plankton illuminating the Atlantic Ocean at Barra de Valizas, Uruguay. The blue glow is caused by a species of dinoflagellate, probably Noctiluca scintillan. The light is emitted from small organelles within the cells and is generated by a chemical reaction known as a luciferin-luciferase reaction. When the organism is disturbed, Luciferin becomes oxidised by molecular oxygen, with the help of the catalyst luciferase. As a result, an inactive oxyluciferin and light is produced. It is thought that N. scintillans may use bioluminescence for many different purposes. It could be used as a defence against predators, an offensive strategy to keep away other predators from their prey, or as a means of communication. The image, which was featured on Earth Picture of the Day, was take in June 2014 with an exposure time of 15 seconds. -Jean Original image: http://www.fefobouvier.com/Astrofotografia/i-W5J2Sx8 Image of the day: http://epod.usra.edu/blog/2014/08/bioluminescence-and-galactic-glow.html

This is the Blue Lagoon Spa located close to Reykjavik, Iceland. The pools are heated by geothermal energy, and the temperature averages 37-39°C. The source of the energy comes from the processes associated with the opening of the Atlantic Ocean and the MOR which stretches across Iceland, and the spa and pools themselves are formed in a solidified lava field. To read more about the pools and Geothermal energy head to the links below. -LL http://www.extremeiceland.is/exotic-bathing http://www.renewableenergyworld.com/rea/tech/geothermal-energy http://www.theenergylibrary.com/node/11418

Crepuscular rays As the sun nears dawn over the Atlantic Ocean near St Ormond by the Sea in Florida, an optical effect known as crepuscular rays becomes visible as the glowing orb shines through the clouds. The originate in high rising cumulus behind the layer of altocumulus onto which the rays are projected as on a screen. The divergence from the point in the sky where the sun is rising is due to perspective effects, much like railway tracks or furrows in fields appear to converge at a distance. They usually occur around dawn or dusk, and the name comes from the Latin for twilight.  Loz Image credit: David Wade via EPOD http://www.atoptics.co.uk/atoptics/ray1.htm