next »

TRAILBLAZERS
for students

ArchaeoFind
Archaeology News
Articles
Browse Attachments
Calendar
Downloads
Forum
Gallery
Links
Member Map
Our News Feeds
Submit Article
Tag Cloud
Video Channel

Trailblazers
Play Phaos
Chat
Trailblazers: Virtual Tours
History's Hinge - 'Ain Jalut

[Solomon]

Antarctica Dome from Stargate SG-1
As a Stargate fan, I hope for much in this new research.

Ha!

Survey targets 'ghost' mountains
Scientists look set to undertake a detailed survey of the Gamburtsev mountain range - one of the Earth's most enigmatic mountain groups.

It extends for more than 1,200km and rises to about 3,400m, but is totally buried under more than 600m of ice.


A low resolution topographic map of the Antarctic bedrock shows the Gamburtsev mountains positioned deep in the continent's interior. The proposed survey is a part of a wider initiative that will gather data all the way out to Prydz Bay.

Computer modelling suggests these great peaks were a nucleation point some 30 million years ago for the huge ice sheets now covering the continent.

The study would be a flagship project of the 2007-8 International Polar Year.

"We want to find out what these gigantic mountains are and where they come from; because no-one really knows how they formed," Dr Michael Studinger, a principal investigator on the project, told BBC News.

"They are big puzzle to the scientific community.

 "They are the size of the Alps, so far as we know, and there's really no straightforward explanation as to how you get such high mountains in the interior of a continent," said the researcher from the Lamont-Doherty Earth Observatory of Columbia University, New York.

Scientists from several nations are working together on the proposal. Details have been described here at the American Geophysical Union's Fall Meeting.


The Lambert Glacier drainage basin, East Antarctica, showing locations of the exposed mountains and the Gamburtsev Subglacial Mountains. Arrows show directions of ice flow today (onshore) and in prior times (offshore) when the ice sheet was greatly expanded. Ice surface elevations are in meters (modified from Hambrey et al., 1991). Gl. = Glacier. Dashed line PC offshore is the edge of the Prydz Channel.

Ice histories
The Gamburtsev subglacial range has been virtually unexplored since it was discovered by a Soviet team during the last geophysical year in 1957-8.

On one level, this is hardly surprising. Anyone who goes to that part of eastern Antarctica has to battle hostile weather; temperatures can go down to more than -80C.

And yet, these mountains hold vitally important clues to the origin and evolution of the White Continent, and by extension the climate state experienced on Earth today.

The expedition would be a testing logistical effort as well as a physical one. A tented field camp must be set up deep in the Antarctic wilderness, and supplied with fuel to run the Twin Otter aircraft that will carry out the aerogeophysical survey.

Equipped with a suite of instruments, these planes would sweep back and forth over the ice to map the hidden terrain.

They will trace the mountains' topography, and take gravity and magnetic readings. This data should give telling clues as to the forces that built up the rocks.

One theory holds that the mountains are old "hot spot" volcanoes that punched their way through the Earth's crust, much like the Hawaiian islands have done in the middle of the Pacific.

"We will also look at internal structures in the ice, layers that record the dynamic history of the ice sheet and how it has evolved over time," explained Dr Studinger.

'Inaccessible' pole
The survey will provide crucial new inputs into climate models.

These suggest the snows that fell on the Gamburtsev peaks at the end of the Eocene Epoch were the starting point for great glaciers that eventually merged to form the East Antarctic Ice Sheet.

 It was a period that saw Earth move into a cool phase as it shifted on its orbital axis and carbon dioxide levels in the atmosphere fell.

New knowledge about how ice moves in this region now will inform simulations of Antarctica's future as greenhouse gases rise and the planet warms once again.

"The Gamburtsev story is extremely relevant because in the next century we will probably exceed the levels of CO2 that in our models triggered the growth of the ice sheets," explained Dr Rob DeConto from the University of Massachusetts, Amherst.

"We don't think the ice sheet will melt away at the same level of carbon dioxide that it grew; there is delay in the system. But it is important that we get new data on the Gamburtsevs so we can refine our models."

In addition, the aerial survey is expected to support Chinese efforts "on the ground". These aim to establish a more permanent base from where a drill hole can be sent down through the covering sheet to obtain ice and rock samples.

The survey data should reveal the best places to core. It may even identify locations where future drilling projects can retrieve ancient ices for analysis - ices that are more than a million-and-a-half years old.


The present-day Antarctic ice sheet with ice flow lines, from Barker et al. (1998), modified to show recent ODP drill sites off the Antarctic Peninsula (AP) and Prydz Bay (PB) and drill sites off Cape Roberts (CR) in the Ross Sea. Also marked are the Transantarctic Mountains (TAM) along the western edge of the Ross Sea (ERS), the Ellsworth Mountains (EM) south of the Weddell Sea, the interior Gamburtsev Mountains (GaM), and the continental margin off Wilkes Land (WL).
Gamburtsev Mountain Programs:

    * EOI#934 - The Gamburtsev Mountains: Integrated International Exploration of the Earths Most Enigmatic Mountain Range
          o http://www.ipy.org/development/eoi/details.php?id=934
    * EOI#412 - A Broadband Seismic Experiment to Image the Lithosphere beneath the Gamburtsev Mountains, East Antarctica   - USA
          o http://www.ipy.org/development/eoi/details.php?id=412
    * EOI#440- Antarctic Convergence Zone -- Dome A (ACDA) Program  - China
          o http://www.ipy.org/development/eoi/details.php?id=440
    * EOI#384 - Geoscientific Insights of Greater Antarctica in the area from Gamburtsev Mountains, Amery Ice Shelf to Prydz Bay  - Australia
          o http://www.ipy.org/development/eoi/details.php?id=384
    * EOI#558 - Gamburtsev Mountains: Aerogeophysical Mapping of Bedrock and Ice Targets (GAMBIT)
          o http://www.ipy.org/development/eoi/details.php?id=558
    * EOI# 349 - Aerogeophysical investigation of subglacial environment and lithosphere of East Antarctica (AeroGeo) (RUS)
          o http://www.ipy.org/development/eoi/details.php?id=349

[Sovereign]

Antarctica: home to alien technology?

The iconic monsters from two of the scariest film franchises ever, battle each other on Earth for the first time on film. The discovery of an ancient pyramid buried in Antarctica sends a team of scientists and adventurers to the frozen continent.


There, they make an even more terrifying discovery: two alien races engaged in the ultimate battle.

[jhardy1]

I have to pass this one to a geologist friend of mine,
my guess is plate tectonics and Continental drift  are in some way  a  underlying  factor for this mystery, Is the Earths magnetic pole during a pole
shift a possible part of this puzzle ? So many factors to
consider and include into a hypothesis.

[Solomon]

An interesting geological mystery, that. My main interest here would be in the archaeology of Antarctica. Much is said how that continent is virgin territory in regards minerals, but the ice cap will also have preserved some of the archaeology quite well, I would have thought.

Harrowfield, D.L. [K282]
Archaeology on ice: a review of historical archaeology in Antarctica.
New Zealand journal of archaeology 26: 5-28, 2004.

Archaeology on Ice:
a Review of Historical Archaeology in Antartica

Mike Pearson on Polar Archaeology: The South Pole

Ancient Seal Remains Reveal Warmer Antarctica, Study Says

Management Plan for
Antarctic Specially Protected Area No. 126
BYERS PENINSULA, LIVINGSTON ISLAND, SOUTH
SHETLAND ISLANDS

Two New Dinosaurs Discovered in Antarctica
John Pickrell
for National Geographic News
March 9, 2004

Working in some of the planet's harshest conditions, fossil hunters have found two completely new species of dinosaur in Antarctica. This increases to eight the number of dinosaur species found on the perpetually frozen southern landmass.

The discoveries, made in December, were recently revealed by the National Science Foundation, the body that coordinates U.S. research in Antarctica.

The first, a 190 million-year-old plant-eater from the early Jurassic period, was found by chance on December 7?13,000 feet (3,900 meters) up a mountain. A mountaineer accompanying paleontologists turned up the animal's huge pelvis in an informal search only a few miles from the South Pole.

Two thousand miles (3,200 kilometers) across the continent, and less than a week later, the scant remains of another dinosaur were found?completely by chance?on what once was the bottom of a shallow ocean. This 70-million-year-old dinosaur is the only known Antarctic meat-eater from the late Cretaceous period and is thought to have unusually primitive features for this period. Paleontologists had to trek 8 miles daily (13 kilometers) across treacherous ice floes to reach it.

"We don't get many opportunities to go to Antarctica and there is a short weather window of opportunity each time," said veteran dinosaur hunter Judd Case of St. Mary's College of California in Moraga. Case was on the team that made the coastal discovery. "Yet [Antarctica] consistently turns up new surprises as far as life on Earth goes," he said.

Migration Route

Little is known about the dinosaurs that once roamed what is now Antarctica. All fossils found so far are from the margins of coastal islands or exposed mountain rock faces?the few places free of a thick ice layer. But the continent was not always so cold.

Antarctica has sat at much the same latitude for the last hundred million years. But during the Cretaceous it enjoyed a warmer, lusher climate, similar to that of the U.S. Pacific Northwest today. (The Cretaceous period started 144 million years ago and ended 65 million years ago.)

Case, his co-worker James Martin, and their team originally set out to test a theory about the migration of extinct animals by looking for marsupial fossils on Vega Island, just off the Antarctic Peninsula (the peninsula juts towards South America).

The earliest marsupials are known to be from North America, but their later representatives, and some dinosaurs, are known to be from Australia alone. The researchers believe that animals may have migrated from the Americas, through a warmer Antarctica, and on to Australia. All three continents were likely linked by land bridges during the late Cretaceous.

However, harsh weather trapped the team's boat in ice, and they were unable to pursue their original goal, Martin said. He is a paleontologist at the South Dakota School of Mines and Technology.

Disheartened, the team stopped off on James Ross Island instead. The rocks here are made up of sediments laid down in an ancient sea. As such, the team did not expect to discover fossils of any land animals here, said Martin.

But alongside the typical clams, ammonites (dinosaur-era mollusks), and other sea life, the team started to find some more exotic fragments. Slowly the legs, feet, and portions of the jaws and teeth of a carnivorous dinosaur began to appear. The dead animal had likely been washed out to sea and had settled on the bottom of what would have been the Weddell Sea 70 million or so years ago.

Currently known as the Naze theropod, after the Naze region of the island where it was found, the coastal dinosaur is estimated to have stood just 6 to 8 feet (1.8 to 2.4 meters) tall in life. Theropods are the group of dinosaurs to which allosaurs, tyrannosaurs, and velociraptors belong. Another Antarctic therapod, a large carnosaur, is known, from the previous discovery of a single bone.

In some ways however, the newfound coastal dinosaur was very different from its late Cretaceous contemporaries. "It represents a group of dinosaurs that is rather primitive," Case said. "[The leg bones] have not been fused to the ? foot, as in more advanced theropods and birds." The teeth are also unusual, he said.

The dinosaurs discovered in Antarctica so far present a kind of "relic fauna," Case said, with most groups more commonly associated with other regions at earlier times.

One theory is that newly successful flowering plants were slower to colonize the Antarctic than other continents?possibly because the landmass was cloaked in total darkness for so many months of the year.

During the late Cretaceous, Antarctica was still smothered with the cycads, palms, and ginkos. In other regions these plants were more typically found during an earlier period, the Jurassic. This may explain why older dinosaur types persisted in Antarctica. (The Jurassic period started 210 million years ago and ended 144 million years ago.)

"Wimpy" Sauropod

The discovery of a new sauropod from the 13,000-foot-high (4,000-meter-high) peak of Mount Kirkpatrick, near to Antarctica's Beardmore glacier, was almost as fortuitous as the coastal find.

Fossil hunter William Hammer, of Augustana College in Rock Island, Illinois, and his team, had flown hundreds of miles inland by helicopter to continue the excavation of a dinosaur they discovered there in 1991. Cryolophosaurus ellioti (an early Jurassic carnivore) was embedded in solid rock, in a site that was a soft riverbed 200 million years ago.

While Hammer's team busied themselves with the specimen in hand, mountain safety guide Peter Braddock scoured the area in a casual search for other fossils. "I jokingly said to him 'Keep your eyes down; look for weird things in the rock,'" Hammer recounted.

Braddock found something weird indeed?part of an enormous pelvis, much bigger than the corresponding bones of Cryolophosaurus.

A lot more of this animal, including much of its vertebral column (up to 3,000 pounds, or 1,400 kilograms, of fossil) is being shipped back to the U.S. for analysis. However, a preliminary investigation suggests that the sauropod would have been 6 to 7 feet (1.8 to 2.1 meters) tall and 30 feet (9 meters) in length. Dated to 190 million years old, "the new fossil is from a key time to learn about the early evolution of dinosaur groups," Hammer said.

This may be the largest dinosaur ever found in Antarctica and perhaps the oldest, he said. Even so, compared to later four-legged, plant-eating sauropods (such as brachiosaurs and Diplodocus), the new species is "kinda wimpy," Hammer said. Some sauropods may have reached a whopping 100 feet (30 meters) in length.

Antarctic dinosaurs may have been different in other ways that scientists do not yet understand, said St. Mary's College of California's Case. Some Australian dinosaurs from far southerly latitudes appear to have large eyes, useful in a nocturnal habitat, he said. Future fossil finds may offer clues as to how these animals were adapted to the six months of darkness, which still today restricts Antarctic researchers and all life in polar regions.

"I have no doubt that there is a tremendous fossil record buried under the ice sheet," Case said. "There have already been large numbers of fossil plants and animals recovered," he said, despite the fact that less than 5 per cent of the landmass is exposed for prospecting and finding fossils.

[jhardy1]

I totally agree, The potential archaeology of that region yielding significant finds should be discussed in length and depth in our journals more often; However the funding is scarce and the season is short
in the Antarctica to make it a cost effective venture
for any various scientific communities to
maintain funding, I may get some flack from you as I make this suggestion; Why not sell some of the insignificant finds to private collectors and the public to help maintain funding of an on going research project ? There is just to much stock piling
in the basement of our great Universities and our affiliated Museums.  Example : why should we retain
in our stock piles, 30 examples of a Cave Bear skull ?
Sell 20 and finance a portion of a future Dig !

[Solomon]

Museums and art galleries both tend to have stockpiles that are hardly used. I know of stories when curators have broken artefacts and damaged pictures because there was too little room to store them properly.

In the UK, I know that pictures are loaned free to politicians in government. Perhaps this idea could be expanded and put on a rental basis.

The British Museum, which runs the 'finds' reporting and reward system, returns most artefacts which qualify as 'treasure' because they are not needed by museums. Artefacts not qualifying as treasure need not, of course, be reported at all.

Public-owned galleries do, as we know, sell their art when needed and I therefore suppose that museums may also be able to sell their artefacts. I wonder if this has ever happened and why it is not more common if, as you say, they can have a problem storing many copies of the same item?

Solomon

[Ninetyninestar]

Great read, merry Christmas men.

[Administration]

Isis will be trawling the depths of Antarctica
Robot heading for Antarctic dive
The mysteries of the Antarctic deep will be probed by a new vessel capable of plunging 6.5km (four miles) down.

Isis, the UK's first deep-diving remotely operated vehicle (ROV), will be combing the sea-bed in the region in its inaugural science mission.

Researchers hope to uncover more about the effects of glaciers on the ocean floor, and also find out about the animals that inhabit these waters.

The mission begins in mid-January and will last for about three weeks.

While the scientists and engineers begin their long journey to the Antarctic at the start of January, Isis left the UK shores in November and has only just arrived at its destination.

Once unpacked from its containers, the ROV will be placed aboard the British Antarctic Survey's ship - the RSS James Clark Ross - ready to explore the Marguerite Bay area on the west side of the Antarctic Peninsula.

Diving deep

With Isis, scientists hope to bring the UK to the forefront of deep-sea research.

The submersive vessel, which is based at the National Oceanography Centre (NOC), Southampton, was built in the US in collaboration with the Woods Hole Oceanographic Institution (WHOI). The project cost about ?4.5m, and Isis is based on of WHOI's Jason II remotely operated vehicle.

UK marine scientists can book time on Isis to carry out their research into the deep.

Isis was built to withstand enormous pressure, explained Peter Mason, the Isis project manager at NOC.

It measures 2.7m (9ft) long, 2m (6.5ft) high and 1.5m (5ft) wide, and weighs about 3,000kg (6,600lb) in the air.

Ten kilometres of cable connect it to its "mother ship", allowing scientists to control the vehicle and receive the data it collects in real-time.

On the ROV, Mr Mason said, were lights, cameras to produce high-quality video and still pictures, sonars for acoustic navigation and imaging, and two remotely controlled manipulator arms to collect samples or place scientific instruments on the sea-bed.

Isis, he added, also had extra capacity to carry a range of scientific tools, such as borers, nets etc, so that scientists could tailor the vehicle to their research needs.


National Oceanography Centre, Southampton

Isis is the new UK Remote Operated Vehicle that will be based at the Southampton Oceanography Centre, UK . Isis has been developed in parallel with the ROV Jason II at the Woods Hole Oceanographic Institution, USA.
Isis is deployed from a mother ship and can operate as deep as 6500m. She has a digital video camera, digital photography camera, a number of sensors and two articulated arms to grab samples. The ROV is remotely operated from a control van on board the ship, where pilots and scientists can obtain data in real time.
   
The sea-trials were conducted in Bahamian waters along the contiental shelf around Eleuthera island between 6-12 March 2003 on R/V Atlantis voyage 7, Leg XXX. ISIS was deployed from R/V Atlantis four times and was tested at depths between 800 and 4300 m.

On March 7th, Isis conducted its inaugural dive to 840m, where it reached a wite sediment sea-floor.

On March 8th, ISIS Dive 002 was conducted to a depth of ca.2000m for an extended dive with bottom time slightly in excess of 6 hours.

On March 9th, Isis dove to abyssal depths spending approximately 5 hours on the seabed at depths in excess of 4300m. During this dive Isismade a transect up the slope while taking excellent video and still images of abyssal fauna, the white fine sediment seafloor and rocky outcrops.

Quicktime movie: ISIS deployment

ISIS: Size, Weight, Power

[Sovereign]

The Rutford Ice Stream -- a 2-km thick, fast flowing ice stream draining part of the West Antarctic ice sheet -- where the drumlin discovery was made. (Image courtesy of British Antarctic Survey)

Antarctic hill surprises experts

Scientists have discovered a warehouse-sized drumlin -- a mound of sediment and rock -- actively forming and growing under the ice sheet in Antarctica. Its discovery, and the rate at which it was formed, sheds new light on ice-sheet behaviour. This could have implications for predicting how ice sheets contribute to sea-level rise. The results are published this week in the journal Geology.


The Rutford Ice Stream -- a 2-km thick, fast flowing ice stream draining part of the West Antarctic ice sheet -- where the drumlin discovery was made. (Image courtesy of British Antarctic Survey)

Drumlins are well known features of landscape scoured by past ice sheets and can be seen in Scotland and Northern England where they were formed during the last ice age. They form underneath the ice as it scrapes up soil and rock, and they slow down the rate at which the ice can flow.

Scientists from British Antarctic Survey (BAS), Swansea University and NASA's Jet Propulsion Laboratory Pasadena used a new technique of time-lapse seismic surveys to find the drumlin, and how it formed over time.

Lead author Dr Andy Smith of BAS says, "This is the first time anyone has observed a drumlin actually forming under the ice. These results will help us interpret the way ice sheets behaved in the past, and crucially, will help predict how they might change in the future".

To the team's surprise the drumlin grew ten times faster than they had ever expected, giving a new and important insight into the drag on the underside of the ice and hence how fast ice sheets are able to flow. The study took place on the Rutford Ice Stream -- a 2-km thick, fast flowing ice stream draining part of the West Antarctic ice sheet.

The team used seismic reflection data gathered three times over the last 13 years to map the changes beneath the ice.

Second author Professor Tavi Murray of Swansea University's School of the Environment and Society says, "The new study was recently described at a conference as 'hunting drumlins in the wild'. The analogy with wildlife is good. We learn a lot more from seeing an animal born and growing up, than just dissecting an ancient body. The same is true of drumlins. By observing the birth and growth of this drumlin, we can see that the landscape beneath an ice sheet is changing at a rate faster than previously thought".

The paper, ' Rapid Erosion and Drumlin Formation Beneath an Antarctic Ice Stream' by A.M. Smith1, T. Murray2, K.W. Nicholls1, K. Makinson1, G. A?algeirsd?ttir2 A.E. Behar3, D.G. Vaughan1 is published in the journal Geology on 23 January.

[Administration]

The samples came from ice in cold, secluded valleys

Ancient microbes 'revived' in lab
Microbes locked in Antarctic ice for as much as eight million years have been "resuscitated" in a laboratory.

Researchers melted five samples of ice from the debris-covered glaciers of Antarctica which range in age from 100,000 years to eight million years.

When given nutrients and warmth, the microbes resumed their activity - although younger microorganisms grew more successfully than the older ones.

Details appear in Proceedings of the National Academy of Sciences.

The findings raise the possibility that ancient bugs, long frozen in ice, will return to life as climate change causes the glaciers to melt, flushing their genetic material into the oceans.

However, experts say this process has been going on for billions of years, and is unlikely to cause human disease.

Kay Bidle of Rutgers University in New Jersey, US, and colleagues extracted bacteria from ice found between three and five metres beneath the surface of a glacier in the Beacon and Mullins valleys of Antarctica.

"The ice sheets are continually undergoing accumulation, so they are flowing outward and the ice is lost through sublimation or calving into the ocean," explained co-author David Marchant of Boston University, US.

"What you have to do to get very old ice is go to secluded, very cold areas, where small alpine glaciers are covered by debris."

The combination of slow-moving glaciers with a debris covering that prevents ice from subliming - or evaporating - means that very ancient ice is preserved in these regions.

The ice gets older as it flows away from the headwall, where the snow and ice of the glacier first accumulates.

The researchers took five samples that were between 100,000 and eight million years old and were able to extract DNA and microbes from them. More organisms were found in the young samples than in the old.

Radiation damage

"We tried to grow them in media, and the young stuff grew really fast," Dr Bidle explained.

"We recovered them easily; we could plate them and isolate colonies."

The cultures grown from organisms in the 100,000-year-old ice doubled in size every seven days on average.

By contrast, microbes from the eight million-year-old ice grew much more slowly, doubling every 30-70 days.


A scanning electron microscope revealed bacteria-like cells (arrows)

This suggested some microorganisms in this old ice were alive, but only just. Their DNA had been severely damaged by long exposure to cosmic radiation. This radiation is stronger at the poles, where the Earth's protective magnetic field is weakest.

The researchers were unable to identify them as they grew, because their DNA had degraded so much.

The researchers found that DNA in the five samples examined showed an exponential decline in quality after 1.1 million years.

'Gene popsicles'

In the younger samples, the team found evidence of some of the most common bacteria around today, including the firmicutes, proteobacteria and actinobacteria.

But the team also compared genetic sequences extracted from the ice to known genes of modern bacteria. Curiously, there were few matches, meaning the ancient microbes may have had genes that were new to science.

Dr Bidle and his colleagues describe the glaciers as "gene popsicles" containing DNA that can be acquired by existing organisms when it is thawed.

Eske Willerslev, of the University of Copenhagen, Denmark, who was not involved in the research, described the work as "very significant".

But he cautioned that, as with most claims of ancient microbes being revived, contamination of samples with genetic material from modern microbes was always a possibility.

"These results show patterns that you can't easily explain by contamination," he told ScienceNow, "But I would feel more comfortable with the results if they had been replicated in two independent labs."

Dr Marchant said temperatures in the Beacon and Mullins valleys were so cold that any liquid melting on the surface only penetrated about 5cm into the ice. Samples were retrieved from below this depth in all cases.

"There's really no chance for modern contamination," he explained.

The team suggests that because DNA in the old ice samples had degraded so much in response to exposure to cosmic radiation, life on Earth is unlikely to have hitched a ride on a comet or on debris from outside the Solar System - as some scientists have suggested.

"Given the extremely high cosmic radiation flux in space, our results suggest it is highly unlikely that life on Earth could have been seeded by genetic material external to this Solar System," they wrote in their scientific paper.

Dr Marchant added: "The other thing that's interesting about this is the connection to Mars. There's near-surface ice on Mars where the surface landform looks identical to what you'll see in Beacon Valley."

On Saturday, Nasa launched its Phoenix spacecraft on a nine-month journey to the Red Planet. It will dig below the surface of Mars' northern plains to collect samples of soil and near-surface ice for analysis.

Fossil genes and microbes in the oldest ice on Earth

Kay D. Bidle *, SangHoon Lee *{dagger}, David R. Marchant {ddagger},  and Paul G. Falkowski *{sect}�

*Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, and {sect}Department of Geological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901; {dagger}Polar Research Institute, Korea Ocean Research and Development Institute, Incheon 406-840, Korea; and {ddagger}Department of Earth Sciences, Boston University, Boston, MA 02215

Edited by David M. Karl, University of Hawaii, Honolulu, HI, and approved June 26, 2007 (received for review March 9, 2007)

Although the vast majority of ice that formed on the Antarctic continent over the past 34 million years has been lost to the oceans, pockets of ancient ice persist in the Dry Valleys of the Transantarctic Mountains. Here we report on the potential metabolic activity of microbes and the state of community DNA in ice derived from Mullins and upper Beacon Valleys. The minimum age of the former is 100 ka, whereas that of the latter is {approx}8 Ma, making it the oldest known ice on Earth. In both samples, radiolabeled substrates were incorporated into macromolecules, and microbes grew in nutrient-enriched meltwaters, but metabolic activity and cell viability were critically compromised with age. Although a 16S rDNA-based community reconstruction suggested relatively low bacterial sequence diversity in both ice samples, metagenomic analyses of community DNA revealed many diverse orthologs to extant metabolic genes. Analyses of five ice samples, spanning the last 8 million years in this region, demonstrated an exponential decline in the average community DNA size with a half-life of {approx}1.1 million years, thereby constraining the geological preservation of microbes in icy environments and the possible exchange of genetic material to the oceans.

Author contributions: K.D.B. and S.L. contributed equally to this work; K.D.B., S.L., and P.G.F. designed research; K.D.B. and S.L. performed research; K.D.B., S.L., and D.R.M. contributed new reagents/analytic tools; K.D.B., S.L., D.R.M., and P.G.F. analyzed data; and K.D.B., S.L., D.R.M., and P.G.F. wrote the paper.

The authors declare no conflict of interest.

Freely available online through the PNAS open access option.

�To whom correspondence should be addressed.
Paul G. Falkowski, E-mail:

www.pnas.org/cgi/doi/10.1073/pnas.0702196104