R.A. Hartley et al.
This image of the ancient buried landscape discovered deep beneath the sediment of the North Atlantic Ocean was made using sound waves bounced off different rock layers. An ancient meandering riverbed is visible.
By
updated 7/11/2011 2:06:10 PM ET 2011-07-11T18:06:10

Buried deep beneath the sediment of the North Atlantic Ocean lies an ancient, lost landscape with furrows cut by rivers and peaks that once belonged to mountains. Geologists recently discovered this roughly 56 million-year-old landscape using data gathered for oil companies.

"It looks for all the world like a map of a bit of a country onshore," said Nicky White, the senior researcher. "It is like an ancient fossil landscape preserved 2 kilometers (1.2 miles) beneath the seabed."

So far, the data have revealed a landscape about 3,861 square miles west of the Orkney-Shetland Islands that stretched above sea level by almost as much as 0.6 miles.  White and colleagues suspect it is part of a larger region that merged with what is now Scotland and may have extended toward Norway in a hot, prehuman world.

History beneath the seafloor
The discovery emerged from data collected by a seismic contracting company using an advanced echo-sounding technique. High-pressured air is released from metal cylinders, producing sound waves that travel to the ocean floor and beneath it, through layers of sediment. Every time these sound waves encounter a change in the material through which they are traveling, say, from mudstone to sandstone, an echo bounces back. Microphones trailing behind the ship on cables record these echoes, and the information they contain can be used to construct three-dimensional images of the sedimentary rock below, explained White, a geologist at the University of Cambridge in Britain.

The team, led by Ross Hartley, a graduate student at the University of Cambridge, found a wrinkly layer 1.2 miles beneath the seafloor — evidence of the buried landscape, reminiscent of the mythical lost Atlantis.   

The researchers traced eight major rivers, and core samples, taken from the rock beneath the ocean floor, revealed pollen and coal, evidence of land-dwelling life. But above and below these deposits, they found evidence of a marine environment, including tiny fossils, indicating the land rose above the sea and then subsided — "like a terrestrial sandwich with marine bread," White said.

The burning scientific question, according to White, is what made this landscape rise up, then subside within 2.5 million years? "From a geological perspective, that is a very short period of time," he said.

The giant hot ripple
He and colleagues have a theory pointing to an upwelling of material through the Earth's mantle beneath the North Atlantic Ocean called the Icelandic Plume. (The plume is centered under Iceland.)

The plume works like a pipe carrying hot magma from deep within the Earth to right below the surface, where it spreads out like a giant mushroom, according to White. Sometimes the material is unusually hot, and it spreads out in a giant hot ripple.

The researchers believe that such a giant hot ripple pushed the lost landscape above the North Atlantic, then as the ripple passed, the land fell back beneath the ocean.

This theory is supported by other new research showing that the chemical composition of rocks in the V-shaped ridges on the ocean floor around Iceland contains a record of hot magma surges like this one. Although this study, led by Heather Poore, also one of White's students, looked back only about 30 million years, White said he is hopeful ongoing research will pinpoint an older ridge that recorded this particular hot ripple.

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Because similar processes have occurred elsewhere on the planet, there are likely many other lost landscapes like this one. Since this study was completed, the researchers have found two more recent, but less spectacular, submerged landscapes above the first one, White said.

Both studies appeared in the Sunday journal of Nature Geoscience.

You can follow LiveSciencewriter Wynne Parry on Twitter @Wynne_Parry. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

© 2012 LiveScience.com. All rights reserved.

Explainer: Tales of seven cities, lost and found

  • Science / AAAS

    The Lost City of Z, a fabled metropolis of unimagined riches deep in the Amazon rain forest, has eluded explorers for centuries. But recently documented traces of a well-planned constellation of walled settlements arranged around central plazas and linked together with arrow-straight roads in the Upper Xingu region of the Brazilian Amazon may be the civilization that gave birth to the legend, scientists say. This image shows the charred remains of a house in the region that was uncovered as part of an archaeological project led by the University of Florida's Michael Heckenberger.

    Click the "Next" label for six more tales of cities lost or found.

    — John Roach, msnbc.com contributor

  • Atlantis legend inspires hotel chain

    Joel Ryan  /  AP

    According to the Greek philosopher Plato, Atlantis was a powerful society that disappeared under the sea in a torrent of earthquakes after it failed to take the city of Athens. Some scholars consider Plato's account as purely fictional; others have scoured the world for evidence of its existence. One disputed theory holds that Atlantis was on a portion of the Mediterranean island Cyprus that was submerged during an earthquake thousands of years ago. The mythical allure of the lost city has spawned a luxury hotel chain. In this image, fireworks explode over the opening of the Atlantis resort in Dubai.

  • What happened to the lost colony of the Americas?

    Gerry Broome  /  AP

    Sometime in the late 1580s, 117 English colonists disappeared while attempting to become the first to settle the New World. Their settlement on what would become Roanoke Island, N.C., was found abandoned in 1590. To this day, scientists, scholars and the plain curious can't agree on what happened. Some people believe the colonists assimilated with neighboring Native Americans; others think they were either killed by their neighbors or sunk at sea while trying to flee. In the image shown here, Frank Ray, a member of the Lost Colony Center for Science and Research looks for clues that could help solve the mystery.

  • Lost city of Ubar found

    NASA

    From about 2,800 BC to AD 300, the city of Ubar in the Arabian Desert served as an outpost for the lucrative trade in frankincense, a sweet-smelling gum resin. Then, according to myth, the city sank in the sand, lost forever. And so it was until archaeologists armed with everything from ancient texts to remote-sensing technology on the space shuttle went looking for the lost city. The diffuse reddish streaks in this radar image from the space shuttle show ancient paths leading to and around the ancient site, which had literally sunk into an underground water hole. Ubar's discovery is an example of scientific sleuthing verifying ancient lore.

  • Lost city of the Incas remains a mystery

    Giulio Magli

    In 1911, U.S. explorer Hiram Bingham scrambled up a steep mountain side in southern Peru and encountered an ancient city of sorts beneath the undergrowth. The site, Machu Picchu, is popularly known as the Lost City of the Incas. What exactly the city was, however, remains a mystery. Scholars have variously theorized it was the birthplace of the Incas, a private estate, and a spiritual destination. Prior to Bingham's encounter, the city was lost to the jungle for about 500 years.

  • Itil, lost capital of Khazars, found?

    Dmitry Vasilyev  /  AP

    The excavated buildings shown here south of Moscow, Russia, may be remains of Itil, the capital city of the Khazars, a Russian scientist has reported. The Khazars ruled the steppes from Northern China to the Black Sea between the seventh and 10th centuries. Once conquered by the Russians, Itil disappeared without a trace. Some scholars believe it was swamped by the nearby rising Caspian Sea in the 14th century. Scientist Dmitry Vasiley at Astrakhan State University believes these flamed brick buildings are part of what was once Itil.

  • Layers of Troy found in Turkey

    Warner Bros. via Reuters

    Homer's epic poem the "Illiad" famously describes a war in the city of Troy, replete with tales about the heroic Greek warrior Achilles and a wooden horse. Questions about whether the city really existed appeared resolved in the 1800s when journalists, archaeologists and others zeroed in on a site and excavated the ancient city. The so-called archaeological Troy consists of nine cities built on top of one another and denoted with Roman numerals. Scholars believe Troy VI and Troy VII correspond with the city described in the Iliad. This image from the movie "Troy," which was based on the Iliad, shows the famous Trojan horse.

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