"The probability of a catastrophic levee failure in the Sacramento-San Joaquin Delta in the next 50 years is two in three," Mount said on the sidelines of the American Association for the Advancement of Science (AAAS) annual conference.

Mount gave a worrying presentation to the conference entitled "The Sacramento/San Joaquin Delta: the next New Orleans?"

He said one of the frequent earthquakes in California could destroy the levee system that has been built up since the middle of the 19th century, sending flood water over a wide area.

Mount said it could have a similar impact to the Asian tsunami in 2004.

The Sacramento-San Joaquin delta takes more than 40 percent of California's rainfall and covers some 280,000 hectares (700,000 acres). It is the main source of water for about 23 million people, of California's 34 million population.

But most of the land is below sea level and is protected by more than 1,600 kilometers (1,000 miles) of levees.

Another 5,600 hectare (14,000 acre) zone around St. Louis in Missouri faces a similar threat from the Mississippi river, according to Adolphus Busch, head of the Great Rivers Habitat Alliances.

Busch, a member of the Anheuser-Busch brewing family, said there had been excessive urbanisation in the zone despite major floods in 1993.

He said the housing and development had drastically reduced alluvial grounds that normally sponge up flood waters.

Nicholas Pinter of the University of Southern Illinois said that efforts to protect St Louis against flooding ultimately had increased the risks.

Eighty-five percent of the Mississippi is now held back by levees and the level of the river has risen by four metres (13 feet) since the start of the century, he said.

The situation is now similar to New Orleans, which was devastated last year after Hurricane Katrina smashed it water defences, and in the Sacramento region.

"In spite of 70 years of federal flood control efforts and nearly 40 years of federal flood insurance, the costs of flooding continue to rise and there is no federal policy to provide direction for future actions," said Gerald Galloway, an engineering professor at the University of Maryland.

Galloway said that development had to be restricted in risk zones and water defences had to be strengthened as the authorities in the Netherlands have done since disastrous flooding there.

"If we knew about Katrina 200 years ago, would we have done the same thing again in New Orleans?" Mount asked. "Well, in California we are reinventing our own Katrina as we speak."

Developers want to build 130,000 new homes near the Sacramento-San Joaquin Delta in the Central Valley, Mount said. Further north, Sacramento stands as one of the most at-risk for flooding among large metropolitan areas in the United States because of its location near rivers and the condition of its levees, he said.

Greater rainfall linked to global warming will only increase the risk of catastrophic flooding, according to Anthony Arquez, an expert at the National Oceanic and Atmospheric Administration.

Between December 1811 and February 1812, the frontier outpost New Madrid was shaken by three quakes so powerful that church bells in Boston reportedly began to ring and the course of the Mississippi River was altered.

Zoback said most scientists today agree that the earthquakes each reached at least magnitude 7.

Professor Mark Zoback presented the results of his research into the temblors today at the annual meeting of the American Association for the Advancement of Science in St. Louis.

While most earthquakes are caused by movement at the juncture of rigid tectonic plates, such as California's San Andreas Fault, the New Madrid quake appears to have been caused by the after-effects of a massive glacier that reached down to what is now the middle of Illinois, Zoback's research shows.

According to Zoback, as the climate warmed and the ice melted, the ground was freed of the pressure of the heavy glacier. This constant release of this pressure caused the New Madrid quakes of a century ago.

Zoback warned that earthquakes could continue to hit the area, including large cities such as Memphis and St. Louis, for the next few thousand years.

"There's quite a few people there now and cities such as Memphis and St. Louis would be severely affected," Zoback said.

"What the scientific community must do is continue the fundamental research trying to understand why these earthquakes occur. At the applied level, scientists need to work with state and local officials to make sure the importance of earthquake hazards are considered in the development of building codes and critical structures such as bridges, schools and hospitals," he said.

The possibility of more earthquakes in the area calls for everyone to be prepared, Zoback said.

"It's one thing to know it was part of your past," he said. "It's another to be prepared for it to be part of your future.''

Looking for ice worms in a basin below Panorama Point on Mount Rainier, UPS students Dave Eiriksson, left, and Ben Lee begin digging what became a 12-foot-deep hole before two of the elusive creatures were spotted. "Nobody knows what ice worms do in winter," Lee said of the quest.

Dave Eiriksson and Ben Lee had to dig deep before finding ice worms on Mount Rainier. Lee is studying them for his biology thesis at the University of Puget Sound, analyzing Olympic Mountain specimens to see how they're related to ice worms elsewhere.

"I can't believe it. The elusive ice worm," a happy Ben Lee said after recently finding two on Mount Rainier.

Ben Lee is stalking a creature most people think is a myth — if they've heard of it at all.

"I don't know what we'll see," he warned, loading an ice ax and snow shovel into his backpack. "Nobody knows what ice worms do in winter."

Lee, a senior at the University of Puget Sound, has come to Mount Rainier to find out.

Thriving in conditions that would turn most living things to Popsicles, these inch-long earthworm cousins inhabit glaciers and snowfields in the coastal ranges of Alaska, British Columbia, Washington and Oregon. They move through seemingly solid ice with ease and are at their liveliest near the freezing point of water. Warm them up slightly and they dissolve into goo.

Their life cycle remains a mystery.

But ice worms are beginning to yield their secrets to a few hardy scientists who see broad applications from understanding one of the planet's oddest inhabitants.

Ice worms in literature

Early 20th-century writer Robert Service mentioned ice worms in several books and poems, including this passage in his novel "The Trail of '98":

"In the land of the pale blue snow

Where it's ninety-nine below,

And the polar bears are dancing on the plain,

In the shadow of the pole

Oh, my Heart, my Life, my Soul,

I will meet thee when the ice-worms nest again."

NASA anted up $200,000 last year to explore the worms' cold tolerance and what it might say about the possibility of life on Jupiter's icy moons and other planets. That work could also improve cold storage of organs and tissues for transplantation.

As glaciers shrink in the face of global warming, interest is growing in ice worms and other animals whose habitat could melt away within the next 50 years. National Geographic funded one of the first field surveys to focus on ice-worm ecosystems.

"They're kind of hot right now," Lee said as he and roommate Dave Eiriksson strapped on their gear and headed up the slopes above Paradise.

The rare sunny day was perfect for "worming," as the 23-year-old Lee calls it.

The men followed a snowshoe trail that wound steeply through stands of subalpine fir half-buried in pillowy drifts. More than 600 inches of snow fall here in an average year, and it's hard to imagine anything without fur could survive.

"People don't believe me when I tell them I'm studying ice worms," said Lee, tall and lanky with curly hair and an infectious enthusiasm. "The words just don't go together."

A COLD-LOVING Minnesotan, Lee picked ice worms for his undergraduate biology thesis because they're weird, haven't been studied much and provide an excuse to get out in the mountains. He spent last summer gathering specimens from glaciers across the Olympic range.

In warmer weather, the black worms are hard to miss. As the sun sets, they swarm to the surface to feed on algae, pollen and other digestible debris.

"In some places, they're so thick you can't step without killing tons of them," Lee said.

Before dawn, the worms retreat back into the ice. Their species name, solifugus, means sun-avoiding.

In winter, when algae can't grow and snow blankets the surface, Lee suspects the worms simply stay deep inside the ice, perhaps in a dormant state.

His plan is to root them out.

"That's where we're headed," he said after an hour's uphill trudge, much of it following steps kicked into the snow by previous hikers. He pointed to a bowl below McClure Rocks at an elevation of about 7,000 feet.

It's not a glacier, but the depression is filled with snow year-round and worms are regularly spotted there in the summer.

Kicking up knee-deep powder, Lee plunged down the incline.

On the floor of the basin, he grabbed his snow shovel, held it out like a divining rod and made beeping sounds as he tried to figure out where to dig.

"We're flying by the seat of our pants," he said cheerfully.

ICE WORMS WERE FIRST described in 1887 on the Muir Glacier in Alaska. Famed Seattle photographer Asahel Curtis took pictures of worms on Mount Olympus in 1907 and dubbed them "snow eels."

But fiction, rather than fact, informed Yukon bard Robert Service, who made several references to ice worms in his poems and novels. He was probably inspired by journalist Elmer "Stroller" White, who, during the Klondike Gold Rush of the 1890s published tall tales in the Dawson City, Yukon, newspaper, describing 4-foot-long wigglers that came out of their lairs and chirped like birds when the mercury dropped below minus 74 Fahrenheit.

In "The Ballad of the Ice Worm Cocktail," published in 1940, Service took up the theme and recounted the comeuppance of a boastful British nimrod who gagged when challenged to down a drink containing a "bilious blue" worm. It was really a piece of painted spaghetti, the poem reveals at the end. Bars in Alaska used to re-create the stunt for their customers.

While Service's work survived, ice-worm studies languished for decades.

"A hundred years of research adds up to about this much paper," Lee said, holding his thumb and index finger less than an inch apart.

Searching the Internet, he connected with biologists Dan Shain and Paula Hartzell, who between them probably account for the bulk of the world's ice-worm expertise.

Shain's first exposure came during a 1995 fishing trip to Alaska, when he saw a cartoon worm on a cafe placemat. He thought it was a joke until he saw the real thing on display at the Portage Glacier visitor center outside Anchorage.

A professor at Rutgers University in Camden, N.J., Shain has wrangled money from National Geographic and NASA for his studies on ice-worm physiology.

Hartzell, who worked with Shain, has surveyed more than 80 glaciers and is writing a book on the peculiar community of snow fleas, nematodes and spiders that dwell on the ice. As the largest invertebrate, ice worms dominate this frozen world.

"IT SUCKS TO DIG," Eiriksson observed, panting. He was standing in the bottom of a seven-foot pit, shoveling snow while Lee took a break and gulped down a muffin.

In summer, Hartzell has found worms in blue ice more than six feet below the surface. Lee peered into a crevasse in Olympic National Park and spotted a worm 10 feet down, poking its head out of a sheer ice face.

Hartzell has seen them with their tails anchored in ice and their heads waving in meltwater streams.

She's convinced they travel through tiny fissures in the ice, but other scientists have suggested the worms secrete a substance that melts a path, like a warm knife through butter.

Polar bears weather the cold with thick insulation and the ability to generate their own heat. Antarctic cod have blood laced with antifreeze. Ice worms don't have any of these defenses.

Instead, they have the remarkable ability to boost their cells' energy production when the temperature drops, Shain discovered. "It's equivalent to putting more gasoline in your tank," he said.

The worms also possess cell membranes and enzymes that function and stay flexible in temperatures where most animals' cellular processes creak to a halt.

The downside is extreme sensitivity to heat. At about 40 degrees F, the worms' membranes melt and their enzymes go haywire.

Shain's NASA project focuses on a key enzyme that regulates the worms' energy cycle.

Organs harvested for transplant deteriorate as the cells' energy stores are depleted, he explained. Unraveling the ice worms' metabolism may lead to drugs or chemical solutions that could keep organs alive longer.

It's more of a longshot, but Shain thinks the worms might also hold clues to suspended animation, or cryonics — the freezing of people or organs. In his laboratory refrigerator, worms have lived up to two years with no apparent source of food.

BLUE SHADOW ENGULFED the basin at Mount Rainier where Lee and Eiriksson continued to toil in their wormless hole, now nearly 10 feet deep. A raven perched on a rock and cocked its head to survey the scene.

During warmer weather, when the worms are easier to find, Lee scooped up hundreds from pools of glacial meltwater, packed them in a cooler with snow and FedEx'd them to New Jersey for Shain's enzyme studies.

For his own project, the UPS student is analyzing DNA from the Olympic worms, to see how they're related to other populations.

Hartzell found northern worms are so different from their southern relatives as to almost be separate species. She also found tiny, remnant populations where receding glaciers have stranded colonies.

That doesn't bode well for ice worms' future.

Rising global temperatures are melting glaciers across the globe, and few are vanishing faster than those along the coast of North America.

"When those glaciers are gone, the ice worms are going to be gone," Hartzell said.

BUT NOT YET.

"I found one!" Lee shouted from the bottom of the now-12-foot hole. "I think I see another one," he said, kneeling to paw through the snow.

Using his ice ax for a step, he heaved himself to the surface.

"I can't believe it," he said, grinning. "The elusive ice worm."

In each hand was a chunk of snow and what looked like a dark thread. The shorter of the two worms corkscrewed slowly, then froze — literally.

When Lee touched the tiny spiral, it snapped.

Even ice worms have their limits. Inside the insulating snow, temperatures remain near freezing. But the air temperature had dropped to about 20 F — below the ice-worm survival point.

"Oh well," Lee said. "It's still pretty exciting."

Only two other researchers are known to have found wintering ice worms, both in Alaska late last year.

Now that scientists know they can unearth the worms in winter if they're willing to dig deep enough, studies can begin to tease out the metabolic tricks that allow the creatures to endure months of entombment under the snow.

For Lee, it's back to the lab, where he will continue sorting through his DNA results.

He'll also devote time to another goal: memorizing Service's 140-line ballad, with its fanciful description of ice worms on the Mountain of Blue Snow:

"Yet all is clear as you draw near — for coyly peeking out

Are hosts and hosts of tiny worms, each indigo of snout

And as no nourishment they find, to keep themselves alive

They masticate each other's tails, till just the Tough survive."

Being Celtic is not about blood, tribes and red hair; nor is it about loving folk music and believing in the little people.

In a landmark special to be broadcast tonight, anthropologist Richard Rudgley, who comes from London, aims to separate myth from fact as he reveals the Celtic world.

Chris Malone, producer for Granada TV, joined him on the journey tracing the Celtic tradition across the world and said that it actually originated with the "true Celts" of central Europe.

Mr Malone said, "It is assumed that the Celts are the people who speak a 'Celtic' language like the Scots and Welsh.

"These are the peoples who were pushed to the fringes after the Roman invasion. People also think about the Celtic crosses, and about the whole pagan druid thing.

"But those are all the cliches. When the Romans arrived in Britain, they never described the people as Celts.

"The 'true Celts' were the continental Celts, although they spread across Europe."

He said that Victorian experts made a big mistake in assuming that what we now call the modern Celtic languages were actually from those European Celts.

Patrick Sims-Williams of the University of Wales, Aberystwyth, contributes to the film, demonstrating that ancient Welsh was in Britain before these European Celts arrived.

Neither is there much evidence of migration, according to DNA research from Trinity College in Dublin.

Mr Malone said, "So the word 'Celt' as we understand it only actually started being used in that way in the 18th century, and it has taken on different meanings.

"What we think of as being Celtic is not necessarily the same as those original Celts.

"It has all been reinvented. It is a name for the tribes which were originally here in Britain and Ireland and their coming together has created this myth.

"And in that happening, the English have lost some sense of their individual identity."

He said Iron Age communi-ties like Castell Henllys, visited during the programme, were similar to Celtic settlements in Europe of the same period, but there were key differences.

"Mostly, the similarities are merely copied designs, sometimes copied burial rites."

However the Celtic concept is still important, according to the programme makers.

In reaching his conclusion, Mr Rudgley meets druids, sails in Celtic ships, rides Celtic chariots, and fights with Celtic weapons as he uncovers remarkable archaeological evidence that sheds a whole new light on the European culture.

He contends that, far from being marginal to who we are today, the Celtic tradition is a crucial part of what makes Britain.

Mr Rudgley argues that the Celtic tradition is a golden thread that has been intertwined with the heart of Europe for thousands of years; a Celtic "magic" that is still there for the taking, offering us a basis for a new Europe.

And the significant fact is that the Welsh language and related dialects spoken in places like Cornwall and Brittany preceded the arrival of both Roman and Celtic peoples.

"It is a much older language than that, which gives us some sort of common root and a much more ancient connection," added Mr Malone.

"That precedes the Celts so it is far older than we might assume."

We may not be Celts historically speaking, but we certainly want to be.

As tonight's Channel 4 programme points out, the word has now been reinvented and refers not to the original Celtic peoples of mainland Europe, but the modern "Celtic" areas.

Scotland has its Celtic football team while Wales, for a short period at least, had the Celtic Warriors rugby side.

Celtic music is sold in Irish and other traditional shops. Stones which were in fact carved by medieval monks influenced by the Christian tradition are also described as "Celtic".

And the pagan traditions of our predecessors have been revived by the Eisteddfod druids, which is also sometimes described as a Celtic ceremony. There is also a huge industry of Celtic-themed jewellery, brooches, etc, with traditional intertwined designs.