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By Hum
Look at any map of the Atlantic Ocean, and you might feel the urge to slide South America and Africa together. The two continents just beg to nestle next to each other, with Brazil’s bulge locking into West Africa’s dimple. That visible clue, along with several others, prompted Alfred Wegener to propose over a century ago that the continents had once been joined in a single enormous landmass. He called it Pangaea, or “all lands.”
Today, geologists know that Pangaea was just the most recent in a series of mighty super-continents. Over hundreds of millions of years, enormous plates of Earth’s crust have drifted together and then apart. Pangaea ruled from roughly 400 million to about 200 million years ago. But wind the clock further back, and other supercontinents emerge. Between 1.3 billion and 750 million years ago, all the continents amassed in a great land known as Rodinia. Go back even further, about 1.4 billion years or more, and the crustal shards had arranged themselves into a supercontinent called Nuna.
Using powerful computer programs and geologic clues from rocks around the world, researchers are painting a picture of these long-lost worlds. New studies of magnetic minerals in rock from Brazil, for instance, are helping pin the ancient Amazon to a spot it once occupied in Nuna. Other recent research reveals the geologic stresses that finally pulled Rodinia apart, some 750 million years ago. Scientists have even predicted the formation of the next supercontinent — an amalgam of North America and Asia, evocatively named Amasia — some 250 million years from now.
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By Hum
Even in the world of rare stones, Foxfire is a freak.
It was buried in a place where big gem-quality diamonds aren’t supposed to exist. A Rio Tinto Group ore processor was configured to discard it. And what saved the diamond’s 187.7 carats from being pulverized was a fluke: Its unusual, elongated shape allowed it to slip sideways through a filtering screen.
“It really is a miracle that it was found,’’ said Alan Davies, chief executive officer of diamonds and minerals for Rio Tinto, the operator of Canada’s Diavik mine, Foxfire’s former home. “It’s a rare find, a really rare find.”
That’s the company’s marketing line as it shows Foxfire to prospective suitors on a worldwide tour and promotes it as the largest gem-quality diamond ever found in North America. Luckily for Rio Tinto, rare diamonds are hot, much hotter than bog-standard rough stones. Sales of those fell 18 percent last year, while their uncommon cousins rack up records. Lucara Diamond Corp. just sold an 813-carat jewel named the Constellation for $63 million, making it the most expensive of its kind—$77,649 a carat. Next month, Sotheby’s will offer one that could fetch more, the Lesedi la Rona, which at 1,109 carats is the size of a tennis ball.
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By Hum
A huge area of land which was swallowed up into the North Sea thousands of years ago has been recreated and put on display by scientists.
Doggerland was an area between Northern Scotland, Denmark and the Channel Islands.
It was believed to have been home to tens of thousands of people before it disappeared underwater.
Now its history has been pieced together by artefacts recovered from the seabed and displayed in London.
The 15-year-project has involved St Andrews, Dundee and Aberdeen universities.
The results are on display at the Royal Society Summer Science Exhibition in London until 8 July.
The story behind Doggerland, a land that was slowly submerged by water between 18,000 BC and 5,500 BC, has been organised by Dr Richard Bates at St Andrews University.
Dr Bates, a geophysicist, said "Doggerland was the real heartland of Europe until sea levels rose to give us the UK coastline of today.
"We have speculated for years on the lost land's existence from bones dredged by fishermen all over the North Sea, but it's only since working with oil companies in the last few years that we have been able to re-create what this lost land looked like.
"When the data was first being processed, I thought it unlikely to give us any useful information, however as more area was covered it revealed a vast and complex landscape.
"We have now been able to model its flora and fauna, build up a picture of the ancient people that lived there and begin to understand some of the dramatic events that subsequently changed the land, including the sea rising and a devastating tsunami."
Findings suggest a picture of a land with hills and valleys, large swamps and lakes with major rivers dissecting a convoluted coastline.
As the sea rose the hills would have become an isolated archipelago of low islands.
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