Horizon

Season 36 Episode 17

Volcanoes of the Deep

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Aired Tuesday 9:00 PM Nov 18, 1999 on BBC Two
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Volcanoes of the Deep
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Horizon follows a team of deep sea scientists as they try to raise a group of strange volcanic "chimneys" from the Pacific ocean floor. Discovered only 20 years ago, these so-called "Black Smokers" are towers of rock that spew out torrents of black scalding water, gushing up from the core of the Earth. They are part of a system of underwater hot springs, called hydrothermal vents, which are found on volcanic mid-ocean ridges where the Earth's tectonic plates meet. The vents harbour one of the most extraordinary ecosystems on the planet - animals and plants living in complete darkness, under enormous pressure, one and a half miles under water. Without energy from the sun, they survive instead on a unique form of chemical energy. At the base of the food chain are chemo-synthetic bacteria. Unlike plants which derive energy from the sun, these microbes feed on chemicals like caustic acid and carbon dioxide that come up through the hot springs from deep inside the bowels of the Earth. The bacteria in turn become the basic nutrients for tube worms and other animals higher up the food chain. It has been estimated that thirty of the volcanic chimneys generate the same energy as the largest nuclear power reactors. Inside these vents there just might be the right mix of chemicals, and enough energy to have created the very first building blocks of life, billions of years ago. Many scientists now believe that it is in places such as these where life on Earth could have begun. The structures are impossible to study properly on the ocean floor. So one team of scientists, led by Professor John Delaney from the University of Washington in Seattle, have decided to raise a group of these giant chimneys, intact, from the seabed and bring them up to the surface to study on land. The hope is that if enough can be understood about these ecosystems, then eventually a model of the exact conditions required for the origin of life can be recreated in a laboratory. In the past, marine geologists have brought up samples of these chimneys using crude dredging or grabbing techniques. But Delaney's plan uses a cage to secure the chimneys. A diamond-studded chain-saw, operated by a remote-controlled robot, would be used to cut the chimney intact from the ocean floor. The chimney would then be delicately raised to the surface by a rope and winch system. The plan was fraught with difficulty. No-one knew if the columns of rock could be cut by the chainsaw, or if the natural fractures in the volcanic chimneys would cause them to break before they could be raised. The film follows the team through a year of engineering tests and minute mapping of the ocean floor, and subsequently as they embark on their expedition to raise the Black Smokers to the surface. Things did not go smoothly for the team. The recovery expedition was plagued by bad weather and equipment problems. In the end the expedition was only partially successful. The scientists did manage to recover four of the chimneys - not entirely intact, but full of microbial life - providing scientists with a good range of samples to analyse, which may one day point to these hydro-thermal vents being the cradle of life on Earth.moreless
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