The mid ocean ridge systems are the largest geological features on the planet. The Mid-Atlantic Ridge (MAR) is a mostly underwater mountain range in the Atlantic Ocean that runs from 87°N -about 333km south of the North Pole- to subantarctic Bourvet island at 54°S.
The MAR is about 3 km in height above the ocean floor and 1000 to 1500 km wide, has numerous transform faults and an axial rift valley along its length.
A study led by ANU has solved the 168-year-old mystery of how the world's biggest and most active volcanoes formed in Hawaii.
The study found that the volcanoes formed along twin tracks due to a shift in the Pacific plate's direction three million years ago.
Lead researcher Tim Jones from ANU said scientists had known of the existence of the twin volcanic tracks since 1849, but the cause of them had remained a mystery until now.
"The discovery helps to better reconstruct Earth's history and understand part of the world that has captivated people's imagination," said Mr Jones, a PhD student from the ANU Research School of Earth Sciences (RSES).
"The analysis we did on past Pacific plate motions is the first to reveal that there was a substantial change in motion 3 million years ago. It helps to explain the origin of Hawaii, Earth's biggest volcanic hotspot and one of the most popular tourist destinations in the world."
Twin volcanic tracks exist in other parts of the Pacific, including Samoa, and the study found that these also emerged three million years ago.
Mr Jones said this kind of volcanic activity was surprising because it occurred away from tectonic plate boundaries, where most volcanoes are found.
"Heat from the Earth's core causes hot columns of rock, called mantle plumes, to rise under tectonic plates and produce volcanic activity on the surface," he said.
"Mantle plumes have played a role in mass extinctions, the creation of diamonds and the breaking up of continents."
Co-researcher Dr Rhodri Davies from RSES said the twin volcanic tracks emerged because the mantle plume was out of alignment with the direction of the plate motion.
"Our hypothesis predicts that the plate and the plume will realign again at some stage in the future, and the two tracks will merge to form a single track once again," Dr Davies said.
"Plate shifts have been occurring constantly, but irregularly, throughout Earth's history. Looking further back in time we find that double tracks are not unique to young Hawaiian volcanism - indeed, they coincide with other past changes in plate motion."
Hawaii sits at the south-eastern limit of a chain of volcanoes and submerged seamounts which get progressively older towards the north west.
The researchers worked with the National Computational Infrastructure at ANU to model the Pacific plate's change in direction and formation of the twin volcanic tracks through Hawaii.
The study titled 'The concurrent emergence and causes of double volcanic hotspot tracks on the Pacific plate' is published in Nature.
Source: The Australian National University, Canberra.
A quarter of a billion years ago, long before dinosaurs or mammals evolved, the 10-foot (3-meter) predator Dinogorgon, whose skull is shown here, hunted floodplains in the heart of today's South Africa.
In less than a million years Dinogorgon vanished in the greatest mass extinction ever (the End-Permian Extinction, a/k/a "The Great Dying"), along with about nine of every ten plant and animal species on the planet.
Luke Abrahams - Everyone loves a good book right? Well, guess what. A savvy reddit user has put together this awesome literary map of the world that shows what everyone's mad for reading.
Bored of Harry Potter, tired of the Millennium trilogy, can’t be bothered to finish War and Peace? Well this map will make your morning commute that little more interesting.
Thanks to reddit user Backforward24, you can now see what the entire world’s favourite books are.
Each book represented in the map is marked by that country’s most famous or important novel.
Obviously the map is going to cause quite the stir. For Russia, for example, Backforward24 went with Leo Tolstoy’s War and Peace, but we’re sure many of you will make a case for one, if not several of Dostoevsky’s works.
The UK has Pride and Prejudice, Spain – Shadow in the Wind, Iran – Persepolis and Ireland – Ulysses. The USA? To Kill a Mockingbird, of course and Canada – Anne of Green Gables, but it should really have been Atwood’s Handmaid’s Tale…
What is amazing though, is when you scroll over places like Africa and Asia.
We’re all down on our classics (those lovely books we all had to read at school), but have you ever picked up a copy of Sony Labou Tansi’s The Antipeople?
Thought not. Off to the bookshop wethinks!
See how one man is single-handedly planting a forest to save his river island in India.
Since 1979, Jadav Payeng has been planting hundreds of trees on an Indian island threatened by erosion. In this film, photographer Jitu Kalita traverses Payeng’s home—the largest river island in the world—and reveals the touching story of how this modern-day Johnny Appleseed turned an eroding desert into a wondrous oasis. Funded in part by Kickstarter, "Forest Man" was directed by William Douglas McMaster and won Best Documentary for the American Pavilion Emerging Filmmaker Showcase at the Cannes Film Festival in 2014.
Experience the colossal geologic forces that shaped our continent over 3 billion years.
Researchers from Botanic Gardens Conservation International compiled the list, finding that at least 10,000 tree species are at risk of extinction
It may seem hard to believe, but until recently, researchers could only really guess as to the number of tree species on Earth. But a new project recently completed by U.K.-based Botanic Gardens Conservation International has finally come up with a solid number: there are 60,065 tree species globally.
According to a press release, researchers at the organization spent more than two years poring through 500 botanical collections and sources and consulting with global tree experts to come up their database, which is now available on BGCI’s website. The database not only lists the tree species, but also includes their national distribution and conservation status.
“Although it seems extraordinary that it has taken us until 2017 to publish the first global, authoritative list of tree species, it is worth remembering that GlobalTreeSearch represents a huge scientific effort encompassing the discovery, collection and describing of tens of thousands of plant species,” says BGCI Secretary General Paul Smith. “This is ‘big science’ involving the work of thousands of botanists over a period of centuries.”
A paper on how the database was compiled and its findings appears in the Journal of Sustainable Forestry.
Agence France-Presse reports that the survey suggests that Brazil is the world tree champ with 8,715 species, including 4,333 endemic species, or trees that only occur in that country. Colombia comes in second with 5,776 species and Indonesia is third with 5,142.
But the list isn’t just about leafy bragging rights. “BGCI's main reason for publishing the list is to provide a tool for people trying to conserve rare and threatened tree species,” the organization writes in its press release. In fact, it found 10,000 species of trees are threatened with extinction and there are 300 species identified with 50 or fewer individuals left. Mark Kinver at the BBC reports that one of those is Karomia gigas, a tree in Tanzania that has only six specimens remaining.
“Getting location information, such as which countries do these trees occur in, gives us key information for conservation purposes,” Smith tells Kinver. “That is hugely useful for us in prioritizing which ones we need to do conservation action on and which ones we need to do assessments to find out what their status is.”
This project is just one of several recent studies helping researchers getting a handle on the planet's trees. In 2015, a study found that there are likely more than 3 trillion individual trees on the planet, significantly more than the 400 billion previously proposed. Last summer, ecologists combed natural history specimens to find that the Amazon Basin has at least 11,676 species of trees, estimating that roughly 4,000 species in the area have yet to be discovered.
When they are, they’ll be welcome in the new database, which the AFP reports will be continually updated.
Source: Smithsonian Magazine.