"Much of the activity between the continental shelves takes place deep underwater at the mid-ocean ridges.
HOW TO MAKE A COMPUTER PROGRAM TO MOVE CONTINENTS CRACK
More than two billion cubic metres of rising molten rock - magma - had seeped into a crack between the African and Arabian tectonic plates, forcing them further apart.Īnd it has given Dr Wright's team a unique opportunity to witness plate tectonics - the science of how continents are formed and move - at first hand. The most dramatic event came in September 2005, when hundreds of deep crevices appeared within a few weeks, and parts of the ground shifted eight metres, almost overnight. But the gradual build-up of underground pressure can lead to occasional bursts of cataclysmic activity. It's here that two mighty shelves of continental crust, the African and Arabian plates, meet - and are tearing the landscape apart.įor most of the time, this happens at around the same speed that human fingernails grow - about 16mm a year. "These changes to the continental character might have contributed to the Great Oxygenation Event on Earth - and, consequently, to the origin of life as we know it," suspects Chowdhury.The 28-strong team is led by University of Leeds geophysicist Dr Tim Wright, who has secured a £2.5 million grant from the Natural Environment Research Council (NERC) to study the seismic events taking place in the remote Afar desert of Northern Ethiopia. The researchers assume that the destruction of the early iron-magnesium rich continental crust was crucial for the formation of the silicon-rich continents and that it was the reason why these continents could rise above sea level to a larger extent. in places where one plate moves under another. On the old, still hot Earth, thin layers peeled off from the Earth's crust whereas on the present-day Earth, chunks of the continental crust break off in the collision zones, i.e. "Over time, the continental crust became prone to preservation during continent-continent collision," says Priyadarshi Chowdhury. Continental recycling still takes place today when two continents collide, but it progresses more slowly and in a different manner than it used to. On the young Earth, continents were recycled all the time. More uniquely, the study demonstrates how the Earth's earliest continental crust - richer in iron and magnesium - was destroyed some two or three billion years ago and how the present continental crust - richer in silicon - formed from it.Ĭontinental recycling is the order of the day Their new thermomechanical computer model supports the growing notion that perhaps plate tectonics was already operating approximately three billion years ago. These are the questions that the German-Swiss research team investigated. The Earth's crust slowly assumed its present dynamic form: in some places the plates go into the mantle in other places new plates form from the hot material that rises from the interior of the Earth.Īlso, the question when plate tectonics first emerged is not the only one that remains unanswered it is also unclear whether that process has always been the same and whether continents last forever or are recycled. The question when they emerged is much disputed. "We haven't found anything comparable anywhere else in the universe."Įven though the young Earth did have continents and oceans, there were initially perhaps no plates and, consequently, no plate tectonics. "These properties render the Earth habitable," says Sumit Chakraborty. Generally speaking, there are two types of crust on Earth: a lighter continental crust that is rich in silicon and constitutes the dry land above sea level, and a denser oceanic crust where water gathers in the form of large oceans. As it cooled, solid rock and the Earth's crust formed. There was a phase - perhaps even several - when it was mainly composed of molten rock. The Earth formed approximately four and a half billion years ago. Hotly disputed: when did plate tectonics emerge?
Priyadarshi Chowdhury and Prof Dr Sumit Chakraborty from Ruhr-Universität Bochum, together with Prof Dr Taras Gerya from the Swiss Federal Institute of Technology in Zürich (ETH), present their work in the journal Nature Geosciences.
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