FURNESS archaeologists believe a metal detector enthusiast might have stumbled on an important Viking burial site after unearthing an ornate merchant's weight.

The man was pottering around Low Furness farmland before Christmas when his detector's bleeping led him to a piece of lead 20cm beneath the soil, reports Jennie Dennett.

When it was unearthed, a 70g weight, 42mm long piece inlaid with an ornate bronze and enamel design depicting what look like entwined mythic beasts and two men with crossed swords emerged. The pattern indicates that it dates back to between AD 1030 and AD 1130.

It has already been described by The British Museum as a "remarkable" find and is setting Viking historians abuzz since it could challenge the textbook theories on the kind of Scandinavian raiders who put down their roots in Cumbria.

The metal detector enthusiast, who is shying away from the limelight, handed-over the rare relic to Lancaster University archaeology tutor Steve Dickinson, who is leading a series of digs around nearby Urswick.

"This chap has rung me before with stuff which has turned out not to be much but when I saw this I was absolutely gob-smacked," said Ulverston-based Mr Dickinson. "I have worked on Viking period sites before but usually you don't get to see anything as exceptional as this in your whole career. It's a really defining moment."

Archaeologists believe weights like the one unearthed were used by Viking merchants to measure out silver prized by the Nordic newcomers above everything, including gold. They have been found before but rarely with such ornate decoration and never in South Lakeland.

Mr Dickinson believes there are now more finds to be made including Viking graves.

"You don't just drop something like this and walk away," he said. "It would be a bit like someone losing a Rolex in a field."

To safeguard the site he is keeping its precise location a closely guarded secret while further exploration is under way, co-ordinated by First Light, a three-year archaeological project that is investigating the heritage of Low Furness.

If his hunch turns out to be right, it would be the second significant burial site recently unearthed in Cumbria after South Lakeland-based Kendal metal detecting enthusiasts picked-up two Viking brooches in March 2004 at Cumwhitton, near Carlisle. That was a find that led to the discovery of six Viking graves the first unearthed since the mid 19th century.

Mr Dickinson believes this latest discovery challenges the idea that Furness and the Lake District were something of a Viking backwater, settled by Viking peasants in the 11th century who scraped a poor living from farming. Place names with clear Norse roots like those ending in thwaite' the Norse for clearing show us they were here. But if there is a burial site of a rich man indicated by this extremely nice weight Mr Dickinson argues that Furness at least was actually an important place to settle in its own right, conveniently situated mid-way between the two big Viking centres of Dublin and York.

But on its own, Ben Edwards, author of The Vikings in North West England, says the find reinforces existing ideas about our Scandinavian forefathers. "Where there are settlers there are always merchants who go round to make money out of them."

It is hoped the British Museum's experts, who are preserving the weight, will soon issue their thoughts on the discovery, along with a valuation.

Meanwhile, Mr Dickinson is hoping to be able to unearth more interesting artifacts to report at the Furness Big Dig event about local archaeology at Ulverston's Coronation Hall on January 27.