http://www.guardian.co.uk/science/story/0,,1772731,00.html
Humans not to blame for ice age mass extinction
Alok Jha, Science correspondent
Thursday May 11, 2006
A rare good-news story for those concerned about the impact humans have had on the Earth: the mysterious mass extinction of large mammals at the end of the last ice age was not the fault of our marauding species as previously thought. New research concludes that the disappearance of mammoths and wild horses in the Americas more than 10,000 years ago is likely to have been the result of natural shifts in the Earth's climate.
Dale Guthrie, of the institute of Arctic biology at the University of Alaska, conducted a radiocarbon dating experiment on more than 600 fossilised bones of mammoths, horses and other large mammals from Alaska and the Yukon Territory to test the three proposed explanations for the mass extinction. These are that disease wiped out the animals; over-hunting of mammoths by humans led to a shift in the local environment, reducing the grasslands and inadvertently killing off other species; and the "blitzkrieg" idea, which imagines newly arrived human hunters devastating large mammals, driving mammoths and horses to extinction and forcing bison and wapiti - a type of deer - into reduced habitats.
By combining his data with archaeological records of how the vegetation in the area changed after the ice age, Dr Guthrie was able to put a timeline on the rise and fall of various animal populations. His results, published today in Nature, found no evidence to support the proposed explanations for the extinction. A disease would imply that many animals died off at once, which the fossil evidence does not show. Dr Guthrie also dismisses the other explanations. "Contrary to [the blitzkrieg] theory my dates show numbers of bison and wapiti were expanding both before and during human colonisation. So we know this was not a simple sequence of bison and wapiti replacing the extinct mammoth and horse," he said.
Instead, the researchers found that the change in climate 13,000 years ago, at the end of the Pleistocene epoch, meant the food available to mammals gradually changed. The increase in temperatures and moisture at the start of the present Holocene epoch encouraged plants unpalatable to horses and mammoths. "These new data show that while humans could have contributed to the Pleistocene extinctions of mammoth and horse, these two species and others were apparently less well adapted to the rise of northern Holocene ecological conditions, favouring to some degree the modern grazing species," said Dr Guthrie.
http://news.bbc.co.uk/1/hi/sci/tech/4757861.stm
Brutal lives of Stone Age Britons
By Paul Rincon
BBC News science reporter
Women were sometimes the victims of violence (Image: Rick Schulting)
A survey of British skulls from the early part of the New Stone Age, or Neolithic, shows societies then were more violent than was supposed.
Early Neolithic Britons had a one in 20 chance of suffering a skull fracture at the hands of someone else and a one in 50 chance of dying from their injuries.
Details were presented at a meeting of the Society for American Archaeology and reported in New Scientist magazine.
Blunt instruments such as clubs were responsible for most of the traumas.
This is not the first time human-induced injuries have been identified in Neolithic people; but the authors say it is the first study to give some idea of the overall frequency of such traumas.
Rick Schulting of Queen's University Belfast and Michael Wysocki from the University of Central Lancashire looked at 350 skulls spanning the period from 4000 BC to 3200 BC.
"We generally think of Neolithic people as living peaceful lives - they were busy looking after cereal crops and rearing livestock," Mr Wysocki told the BBC News website.
"But it was a much more violent society."
Nearly 5% of the skulls showed healed depressed fractures. They found unhealed injuries in 2% of the sample, suggesting these individuals died from their wounds.
But the true scale of the violence still remains unclear due to the nature of the evidence, say the authors. In other simple, small-scale societies, the incidence of death as a result of violence ranges from 8-33%.
"Our data shows 2% lethal cranial injuries, but these are just cranial. The data for other societies is for all lethal injuries, but ours is limited so we can't compare it," Mr Wysocki said.
"A lot of lethal injuries will be to soft tissues and that needn't affect bone."
The researchers suspect that what they are seeing is violence at the local and regional level rather than large-scale warfare involving large sections of the country.
"We could also be seeing raiding parties, cattle rustling, somebody suspecting the other tribe across the hill is practising witchcraft," the University of Central Lancashire forensic anthropologist explained.
"Some of the violence may be domestic; some of it may even be ritualised."
The majority of the traumas were caused by blunt instruments which may have included improvised clubs. But a handful of fractures look like they have been inflicted by flint arrowheads and spearpoints. One of the females in the sample appears to have been the victim of a brutal attack with a stone axe.
Another individual with a suspected projectile fracture appears to have had their ears slashed off - a possible instance of trophy-taking, the researchers speculate.
The research originally appeared in the Proceedings of the Prehistoric Society journal.
Paul.Rincon-INTERNET@bbc.co.uk
http://news.bbc.co.uk/1/hi/england/gloucestershire/4759611.stm
Last Updated: Thursday, 11 May 2006, 02:03 GMT 03:03 UK
Roman graveyard found in quarry
The cemetery contains the remains of more than 100 people
Archaeologists have unearthed a large Roman cemetery in a Gloucestershire gravel quarry.
More than 100 people are believed to have been buried at the site, near Fairford, which dates back 1,600 years.
It is thought the dead were interred according to their age, as children's bodies have been found in one area with adults in another section.
Experts said the find is unusual because no big settlements are known to have existed nearby in the Roman era.
Dr Alex Smith, Oxford Archaeology's project manager said: "Large Roman cemeteries like this are usually only found around towns or substantial settlements, but no such site has been found here yet.
"We believe a small Roman farm lies immediately to the west, and it may be that the cemetery acted as a communal burial ground for the local rural population."
He added: "We hope that further work will reveal more of how people lived and died in this region, around 1,600 years ago."
http://ansa.it/main/notizie/awnplus/english/news/2006-05-09_1096558.html
Augustan head found at new villa
Mosaic floors, baths, atria and coins at site near Rome
(ANSA) - Rome, May 9 - A marble head of the Emperor Augustus has been found at a large and well-appointed Roman villa just discovered outside the capital .
The head, practically a bas-relief, shows the emperor in profile in his middle years .
It will shortly be taken to the newly refurbished Roman Antiquities Museum at Palazzo Massimo near Termini Station to be shown to the public .
Also travelling from the dig site - north of Rome, not far from Hadrian's great villa - will be some 100 gold and silver coins .
The head was found at the bottom of a well at the villa, a large (2,500 square-metre) property built between the second century BC and the first century AD .
"We don't know who the villa belonged to," said dig leader Stefano Musco .
"This is an area dotted with villas, because of its proximity to the administrative and cultural hub that was Hadrian's court" .
The villa also boasts "particularly fine" mosaic floors with characteristic geometrical designs, Musco said .
Other finds were thermal baths, a warehouse and two entrance halls or atria. Augustus (63 BC-14 AD), the adopted son of Jiulus Caesar, was Rome's first emperor .
Fisherman Nets Ancient Statue in Greece
Tue May 9, 7:11 PM ET
ATHENS, Greece - A Greek fisherman has handed over to authorities a large section of an ancient bronze statue brought up in his nets in the Aegean Sea, officials said on Monday.
The male torso was located last week near the eastern Aegean island of Kalymnos, the Culture Ministry said in an announcement.
The one-meter (3-foot) high find belonged to a statue of a horseback soldier, and would have been part of the cargo of an ancient ship that sank in the area. It was taken to Athens to be cleaned and dated.
Together with the torso, the fisherman brought up two small bronze pieces believed to belong to the statue, and a wine-jar from the ancient city of Knidos — in what is now Turkey — dating from the first century B.C, the ministry said.
The seas around Kalymnos are rich in ancient wrecks and have yielded several impressive finds in recent years, including a large female statue now exhibited at the National Archaeological Museum in Athens. The fisherman who netted it in 1995 earned a euro440,000 (US$558,000) reward from the Culture Ministry.
Other scattered pieces of bronze statues found in the area include a head, legs and arms, but it is unclear whether these could match the horseman's torso.
http://ansa.it/main/notizie/awnplus/english/news/2006-05-12_1121483.html
Sabine chariot rewrites history
'Exceptional' find proves independence of ancient city
(ANSA) - Rome, May 12 - An ancient king's war chariot found in a tomb near Rome has helped rewrite the history of the Romans and their Sabine rivals .
"This chariot is an exceptional find," said archaeologist Paola Santoro .
"It shows that the city of Ereteum remained independent long after the Sixth Century BC." "In other Sabine cities like Custumerium, conquered by the Romans, the custom of putting regal objects in king's tombs had died out by that time" .
"We can say that Eretum kept its independence until the Fourth Century BC." Santoro said her team had recovered all the metal parts of the bronze-and-iron decorated chariot and had used echo-soundings to trace the imprints of the long-decayed wooden parts .
"This will enable us to reconstruct the whole chariot," she said .
The chariot, which accompanied the king on his last journey, was placed at the entrance to the tomb, the largest chamber tomb ever found in Italy .
Santoro's team have also found an Etruscan-style terracotta throne - "a metre high, worthy of the king's stature" - and four large bronze cauldrons with bull-hoof supports .
Less than a dozen of this type of cauldron had been discovered before, Santoro said .
The tomb was found in the main room in the three-room complex, next to a wall recess where a wooden coffin containing the king's ashes would have been placed .
The horses that had drawn the chariot would have been sacrificed at the entrance to this room, Santoro said .
Before the discovery of the Sixth-Century BC tomb, two years ago the Eretum dig uncovered a rare religious symbol used by Sabine high priests .
Some scholars think the holy object, called a lituo, was also used by kings of the Sabine tribe, one of Rome's earliest rivals and one which provided the city with its second king, Numa Pompilio .
Only two other examples of the lituo had been found - although it is seen quite often on funerary vases .
The sacred rod, a sort of curved stick, was believed to be a tool which helped priests trace out an area of the sky for watching birds whose passage would determine important decisions such as where to found a city .
Archaeological evidence of the Sabines has until now been extremely scarce and much of the stories about them have been considered legends - such as the famous Rape of the Sabines, in which Rome's first king Romulus sent an expedition to carry off Sabine women to provide wives for his desperately woman-short settlement on the Tiber .
The discovery of the object, some Italian experts believe, provided evidence of how Sabine religious usages shaped the formation of Roman institutions .
It is plausible to suppose that for some time the kings of Rome, many of them from another semi-mysterious tribe called the Etruscans, used the same religious rites as the Sabines and were in fact priest-kings, archaeologists think .
http://www.timesonline.co.uk/article/0,,3-2174545,00.html
Cleopatra's gems rise from the deep
By Roger Boyes
Hundreds of priceless finds will shed light on 1,500 years of Ancient Egyptian history
THE lost world of Cleopatra’s palaces has been dug out of the muddy Mediterranean sea bed by a man dubbed the Underwater Indiana Jones.
The results of Franck Goddio’s excavations, comprising 500 priceless finds that shed light on 1,500 years of ancient history, will be put on public view today for the first time.
President Mubarak of Egypt will open the exhibition in Berlin, and it will later transfer to Paris and London and eventually to a specially prepared site in Egypt.
“It was an astonishing feeling to find and handle beautiful objects that have been touched by Cleopatra,” said M Goddio, a 58-year-old Frenchman who abandoned a career as a financial consultant to pursue his passion for maritime archaeology.
For the past 12 years he has been excavating the sunken harbour of Alexandria, the legendary lost city of Heracleion and the religious centre of Canopus.
Floods, earthquakes and erosion swallowed up these once-vibrant communities. Although some of the recovered fragments have been shown, they have never been put together in a single comprehensive collection.
The Goddio team discovered 5.4m (18ft) red granite statues of an Egyptian king, queen and the fertility god Hapi, as well as thousands of smaller statues of gods and rulers, masks of pharaohs, gold and stone jewellery, and an intact black slab pronouncing import duties on Greek products.
One of the most significant discoveries was the fragment of a shrine, the Naos of the Decades, which made it possible for M Goddio to reconstruct the first astrological calendar in the world.
Among the treasures is a sphinx bearing the face of Ptolemy XII, the father of Cleopatra, a reminder that parts of the royal quarter with its temples, palaces and gardens were in Alexandria’s eastern harbour, where Julius Caesar, Mark Antony and Cleopatra stayed.
Working from 19th-century maps and the results of an early excavation by Prince Omar Tousson, M Goddio set about testing theories about the geography of the sunken harbour area.
What emerged was a picture of a remarkably well-designed metropolis divided by grand canals.
“We showed the designs to port engineers who told us that they couldn’t have done a better job,” he said. “It was not only an act of brilliant engineering it was also beautiful to look at.”
http://www.24hourmuseum.org.uk/nwh_gfx_en/ART37392.html
EXPERTS FIND RARE ROMANI DNA IN NORWICH ANGLO SAXON SKELETON
By Sarah Morley 12/05/2006
The recent discovery of Romani DNA in an Anglo Saxon skeleton has made experts re-think the nature of the city's early population. Picture courtesy Sophie Cabot. © HEART
Experts from Norfolk Archaeology Unit based at Norwich Castle have discovered a rare form of mitochondrial DNA identified as Romani in a skeleton discovered during excavations in a large area of Norwich for the expansion of the castle mall.
The DNA was found in an 11th century young adult male skeleton, and with the first recorded arrival of the Romani gene in this country put at 500 years later, historians may need to re-think the ethnic mix of the city's early population.
Norfolk Archaeological Unit’s lead archaeologist on the dig was Brian Ayres. He told the 24 Hour Museum: “The bones were of a late Saxon Christian. We know this because it was found in a graveyard associated with the church.”
Brian was on the scene when they discovered the DNA in the bones of the young Saxon male - out of the 59 skeletons sampled. Though the excavation was done around the early 90’s the results of the DNA testing has only recently been published to a specialist audience.
DNA testing is a completely revolutionary way of testing and dating bones to find out their origins. Modern methods only recently discovered allow for lots of new links to be made, such as finding where an individual originated from through their genes.
Extracting DNA from ancient bones is a complicated procedure involving removing the DNA from the tooth pulp as the hard tooth enamel preserves the gene. This form of mitochondrial DNA is passed down the female line and the identified gene is only found in the descendants of Romani. According to DNA records the first recorded Romani Gene found in England was in the 16th Century.
Extensive archaeological excavations have unearthed both Roman and Anglo-Saxon finds in and around Norwich. © Norwich City Council
The find is exciting because it paints a more diverse picture of ancient Norwich. Although Norwich has a rich history of cultural diversity, the discovery of first recorded Romani Gene in the country points to new levels of diversity.
“This exciting find emphasises a more cosmopolitan Anglo-Scandinavian society,” explained Brian who went on to say not only does this find show Norwich as an early multi-ethnic society but it gives a wider indication of a more fluid world in the 11th Century, where humans were constantly moving from country to country.
Romani people have a bloody history of persecution, murder and banishment in almost every country they entered. They were accused of witchcraft and almost every crime imaginable. They originated from the ancient warrior classes of North India and are closely linked to the culture of the Punjabi people, also of North India.
The Romani people are known to have been in Byzantine Empire in the 10th century, so it is thought that the only way the Romani Gene could be found in this country so early is if the previous historical records are mistaken.
Another possibility is that if the Anglo-Saxons were also in Byzantium in the 10th century, relations between the Anglo Saxons and the Romani people may have led to the spread of the Romani Gene to Norwich, England.
http://www.newswise.com/articles/view/520388/
Discovery of Oldest Known Art and Agriculture Calendar in New World
MU Researcher Unearths Earliest Known Western Sculptures and Astronomical Alignments in Peru's Temple of the Fox. Andeans Used Myth and Astronomical Markers to Determine Agricultural Calendar.
Newswise — In one of the most significant archaeological and anthropological finds in recent history, Robert Benfer, professor emeritus of anthropology at the University of Missouri-Columbia, has discovered the earliest astronomical alignments and sculptures in the round, which is a sculpture designed to be viewed from many directions and angles, in the New World in Buena Vista, Peru. The Temple of the Fox, an ancient structure in the Chillon Valley that dates back to 2200 B.C., contains sculptures of unprecedented artistic style that can be associated with the agricultural calendar and Andean myth.
"There hasn't been an archaeological finding like this since the early 1980s," Benfer said. "The Temple of the Fox is 1,000 years older than anything of its kind found before. It's also significant because it suggests people organized their lives around Andean constellations and provides evidence of the beginning of flood-plain agriculture."
In temples such as the one Benfer uncovered, the Andeans constructed offering chambers, used them for ceremonies and then built new chambers above the old. Benfer said this protected the Buena Vista site from looters, who came within one inch of the musician statuary while searching for gold and silver in the ancient temple. The well-preserved offering chamber holds ancient pieces of cotton and burned twigs, and Benfer's team used the twigs to radio-carbon-date the various components of the excavation site.
At the entrance to the Temple of the Fox, Benfer unearthed a mural of a fox incised inside a painted llama. He said the mural depicts the significance of the fox in Andean myth and astronomy. The fox taught the ancient Andean civilizations how to cultivate and irrigate plants and, according to Andean myth, is reincarnated by drops of water. Today, the constellation of the fox also is associated with water, and farmers use the call of the fox to predict rainfall.
While excavating the temple and sculptures, Benfer discovered several astronomical alignments at the Buena Vista site that suggest Andeans used astronomical signs and constellations to guide their agricultural activities. The lines incorporate points at the temple entrance, at the offering chamber, on sculptures, and on surrounding ridges that align with the rising and setting sun on days of astronomical significance, such as the equinox and solstices. For example, from west to east, the offering chamber aligns with a modified rock on an eastern ridge, forming a 114-degree azimuth and pointing toward the rising sun on December 21, which is the southern hemisphere's summer solstice. This date begins the season where flood waters rise, El Niño weather patterns are predicted and plants should be planted. On March 21, when flood waters recede, this same line points to the rising Andean constellation of the Fox. In addition, among the ancient statues Benfer excavated in Buena Vista is a personified disk that frowns at the sunset on June 21, the day marking the beginning of the harvest.
Benfer has been working at this site in Peru for the past four years but only discovered the Temple of the Fox in June 2004; the frowning disk was unearthed in June 2005. He said no one could have predicted to find something so old, but he added that other Andean temple sites he has studied contain perfect 114-degree alignments and similar astronomical features, which act as additional evidence to support his findings.
Archaeological and anthropological field school students, including several MU students, have assisted Benfer with his research. His trips to Peru have been funded by the MU Research Board, field schools in the U.S. and Peru, and, most recently, National Geographic. Benfer said he plans to return to Peru to continue the excavation of the Buena Vista site as early as this summer. He and other investigators on his team presented their findings at the annual meetings of the Society for American Archaeology in San Juan, Puerto Rico this month.
Benfer also presented a lecture on the Temple of the Fox and its historical significance to the Archeological Institute of America.
http://news.bbc.co.uk/1/hi/world/americas/4767717.stm
'Brazilian Stonehenge' discovered
By Steve Kingstone
BBC News, Sao Paulo
The stones are well preserved and each weighs several tons
Brazilian archaeologists have found an ancient stone structure in a remote corner of the Amazon that may cast new light on the region's past.
The site, thought to be an observatory or place of worship, pre-dates European colonisation and is said to suggest a sophisticated knowledge of astronomy.
Its appearance is being compared to the English site of Stonehenge.
It was traditionally thought that before European colonisation, the Amazon had no advanced societies.
The archaeologists made the discovery in the state of Amapa, in the far north of Brazil.
A total of 127 large blocks of stone were found driven into the ground on top of a hill.
The layout suggests a temple or an observatory
Well preserved and each weighing several tons, the stones were arranged upright and evenly spaced.
It is not yet known when the structure was built, but fragments of indigenous pottery found at the site are thought to be 2,000 years old.
What impressed researchers was the sophistication of the construction.
The stones appear to have been laid out to help pinpoint the winter solstice, when the sun is at its lowest in the sky.
It is thought the ancient people of the Amazon used the stars and phases of the moon to determine crop cycles.
Although the discovery at Amapa is being compared to Stonehenge, the ancient stone circle in southern England, the English site is considerably older.
It is thought to have been erected some time between 3000 and 1600 BC.
http://news.xinhuanet.com/english/2006-05/11/content_4533769.htm
Top 10 Archaeological Discoveries of 2005 unveiled
www.chinaview.cn 2006-05-11 12:52:01
BEIJING, May 11 -- The Top 10 Archaeological Discoveries of 2005 were announced to the public Tuesday night in Beijing by the Chinese Society of Archaeology, with more than half from outside the Yellow River Valley, considered the cradle of Chinese civilization.
They may shed light on China’s multiple cultural origins, experts said.
The Xiaohuangshan Relics in East China’s Zhejiang Province, which were excavated early last year, are an example.
The relics, which date back 8,000 to 10,000 years, could rewrite the country’s archaeological history as they are much older than the Hemudu site in the province. That site was previously believed to have nurtured the earliest Neolithic culture in China’s south about 7,000 years ago.
At the new site, researchers found several deep ditches which they believe were storerooms and some signs of cooking.
In Southwest China, a large number of pits for sacrifice were found among relics in Zhongshui, Guizhou Province.
Inside the pits, crockery ranging from the late New Stone Age to the Western Han Dynasty (206 B.C.-A.D. 24) was uncovered, providing strong evidence for future research into the rice-growing culture of the Zhongshui area 3,100 years ago.
In East China’s Fujian Province, archaeologists discovered six kilns from the Shang Dynasty (1600-1100 B.C.) in Pucheng, a city in the north of the province.
More than 300 pieces, including pottery, stoneware and bronze implements, have been excavated. Researchers are continuing work in the area.
“It was the first time we found such a large kiln group in the country,” said archaeologist Xu Pingfang.
Since 1990, the State Administration of Cultural Heritage has appointed the Chinese Society of Archaeology to hold the annual archaeological discovery competition. Based on the Cultural Relic Protection Law, the competitors are required to have historic, artistic and scientific values. The latest top spots were selected from about 400 archaeological discoveries in 2005. (Xinhua)
Top 10 ancient sites
1. Xiaohuangshan Relics, Zhejiang Province, Neolithic culture
2. Gaomiao Relics, Hunan Province, pottery for sacrifices
3. Zhongshui Relics, Guizhou Province, prehistoric tombs
4. Liuzhuang Relics, Henan Province, Neolithic culture
5. Maoernongshan Relics, Fujian Province, kiln group from the Shang Dynasty (1600-1100 B.C.)
6. Hengshui Relics, Shanxi Province, cemetery decoration in the Western Zhou Dynasty (1100-771 B.C.)
7. Liangdaicun Relics, Shaanxi Province, graveyard for nobles in the Zhou Dynasty (1100-221 B.C.)
8. Jurong and Jintan Relics, Jiangsu Province, mound graveyards in the Zhou Dynasty (1100-221 B.C.)
9. Huangyangzhuang Relics, Henan Province, courtyards from the Han Dynasty (206 B.C.-A.D. 220)
10. Datong Relics, Shanxi Province, tomb mural in the Northern Wei Dynasty (A.D. 386-534)
(Source: Shenzhen Daily)
Editor: Pan Letian
http://www.nature.com/news/2006/060508/full/060508-11.html
Published online: 11 May 2006; | doi:10.1038/news060508-11
Ancient mariners reveal tales from the Earth's core
Ship logs and pottery show how the geomagnetic field has changed.
Philip Ball
While sailors plied the Seven Seas in the seventeenth and eighteenth centuries, little did they know that their ships' logs would one day help scientists to reconstruct the history of the Earth's magnetic field.
Geophysicist David Gubbins and his co-workers at the University of Leeds in England have used old navigational data, combined with records taken from archaeological artefacts, to figure out how the direction and strength of the magnetic field changed between 1590 and 1840, roughly the time between Francis Drake's voyages on the Golden Hind and Charles Darwin's journey on the Beagle.
Systematic records of the geomagnetic field only exist from around the middle of the nineteenth century, when physicist Carl Friedrich Gauss devised a method to measure it. These measurements show that since that time the strength of the field has fallen gradually by around 0.05% per year.
"A lot of people have been getting very excited that the field strength has been decreasing at this high rate," says Cathy Constable, a geophysicist at the Scripps Institution of Oceanography in La Jolla, California. "They see it as evidence that we're headed for the next geomagnetic reversal."
At a reversal, the Earth's magnetic field fades briefly away before the north and south poles reverse. The process by which this happens is not fully understood, but probably involves changes in circulation patterns in the planet's molten core. Such reversals happen about once every million years.
Gubbins and his colleagues now report in Science that the recent decline only started, by coincidence, around the time the measurements themselves began1. By using navigational logs to extend the record back a further 250 years, they find that the geomagnetic field strength was almost constant until around 1840, and only then started to dip.
"This new record shows that the trend is only temporary," says Constable. So, she says, forecasts of an impending geomagnetic flip are premature.
Before 1840, the best records we have of the planet's magnetic field strength are contained in rocks and archaeological artefacts. Atoms of magnetic material such as iron within the ground or pottery are frozen in line with the Earth's magnetic field when a rock or pot is heated and then cooled, revealing information about the field strength.
Some researchers have found signs in this data that the Earth's magnetic field wasn't decaying as quickly as it is today between 1600 and 1800. But these records are patchy and calculating global field strength from them is fraught with inaccuracy.
To get a better estimate, Gubbins and colleagues have combined these data with more precise information about the direction of the magnetic field over time. Together these data sets can then be plugged into a model of how the Earth's magnetic field is known to behave, to extract a global picture of field strength.
To get the directional information, the researchers raided ship logbooks. Mariners of several hundred years ago would use observations of the Sun or stars to determine 'true north', and then note the difference between this and 'magnetic north' as revealed by their compasses. "It's very surprising how accurate those measurements are," says Jeremy Bloxham of Harvard University, Massachusetts, who collaborated with Gubbins and co-worker Andy Jackson at Leeds in compiling the historical records in the late 1980s.
Sailors would make measurements to the nearest degree, notes Bloxham, making for a relatively precise record. But there are often systematic errors in their notes, caused by the fact that the sailors didn't always know exactly where they were; not, at least, until reliable methods for determining longitude were devised in the eighteenth century. Researchers have spent some 20 years trying to clean up the sailors' data in this regard.
This long process has now revealed a detailed picture of our planet's magnetic field over time. It is not nearly so simple as the field around a traditional bar magnet. Field lines do not simply emanate from the poles of our planet. Instead the field is patchy, with regions of 'reverse flux' where the field lines go in the opposite direction. The Leeds researchers say these patches have altered over the past four centuries: spots in the southern hemisphere that are now clearly evident were barely present at all before 1840, they say.
It seems that something may have happened within the planet's core in the 1800s to change the field's behaviour, they say. The team suggests that the next step should be to look elsewhere in the historical record for other times when the rate of change in the field altered, to better understand what causes such changes.
http://www.courier-journal.com/apps/pbcs.dll/article?AID=/20060514/COLUMNISTS04/605140392
Sunday, May 14, 2006
Archaeological theory would upend history
Byron Crawford
Understandably, mainstream archaeologists usually raise an eyebrow when Jim Michael's name is mentioned.
His relentless research during the past 20 years as president of the 140-member Ancient Kentucke Historical Association would -- if proved correct -- require the rewriting of some important texts of history and archaeology. He also is the author of "Ancient Kentucke Inscriptions."
His quest began in 1986 when Michael, a pre-med graduate from the University of Iowa and then a medical representative for Pfizer Pharmaceuticals, was having lunch with several Kentucky doctors and pharmacists. One person mentioned mysterious inscriptions carved in rock shelters that he had seen in southeastern Kentucky.
Within two years, Michael -- who lives in Louisville and is now 74 -- had photographed several of the strange etchings, or petroglyphs, that he had examined in Kentucky and other states. He sent them to Harvard University researcher Barry Fell and others. He enrolled in archaeology courses at the University of Louisville.
During a program in Louisville, featuring slides of some of the inscriptions of mostly vertical lines and markings, he learned from a fellow presenter that a team of British researchers had been looking for epigraphers -- those who study ancient inscriptions -- to share information on sites in the Ohio Valley. He sent them photographs of some of the inscriptions he had seen.
"They just looked at them and sent them right back, and said, 'This is our Coelbren alphabet,' " Michael recalled.
Coelbren, believed by many to be an ancient Welsh or Druid alphabet, is one of the links that Michael believes will help conclusively prove that emigrants from ancient Britain inhabited much of the Ohio Valley and other regions of North America in the sixth century, hundreds of years before Columbus landed in the Americas.
Theory dismissed
Archaeologist Nancy O'Malley, director of the University of Kentucky's William S. Webb Museum of Natural History, acknowledges evidence that some Europeans journeyed to the new world by "island hopping" to Newfoundland before Columbus arrived. But O'Malley soundly rejects the so-called "Welsh Indian" theory that she says has been circulating since the 18th century.
"There's no credible evidence that the Welsh ever came over here at the time periods they're talking about," she said. "I don't know what makes this such an irresistible theory … but these kinds of notions don't ever die."
However, Robert Pyle, the former state archaeologist of West Virginia, called Michael's findings important and beneficial to archaeology. He said the Ohio Valley inscriptions resemble many markings found in Europe.
Michael added: "It's just a matter of time until they can put it all together and say, 'Okay, this is the way it is. I would like for it to be recognized while I'm still alive, but unfortunately it doesn't work that way."
Byron Crawford's column appears on the Metro page Sundays, Wednesdays and Fridays. You can reach him at (502) 582-4791 or e-mail him at bcrawford@courier-journal.com. You can also read his columns at www.courier-journal.com.